Genetics of Lactose Digestion in Humans

Part of the Advances in Human Genetics book series (AHUG, volume 16)


Lactose is a biologically unique sugar. In contrast to the other nutritionally important disaccharides, the α-glycosides maltose and sucrose, lactose is a β-glycoside. Lactose occurs in large amounts and as a free molecule only in milk. It is thus a biochemical and nutritional characteristic of mammals and is not present in other classes of animals. Sugars more common than lactose and more ancient in evolutionary terms would presumably suffice for the supply of energy to the young mammal. The development of the intricate mechanisms of lactase synthesis in the mammary gland and of lactose digestion in the intestinal tract would therefore run counter to evolutionary economy if lactose did not convey a special selective advantage during the suckling period. Evidence of such an advantage is not available at present. Adult mammals usually do not have access to milk in their natural environment, and their lactose digestion capacity declines after weaning. The human species is no general exception to this rule: in the majority of humans there is a gradual decline of lactase activity during early childhood. Adults with persistent lactase activity and correspondingly high lactose digestion capacity are common in only a few populations. The causes and distribution of this dimorphism of lactase activity in human adults will be the main subjects of this review.


Milk Consumption Breath Hydrogen Lactase Persistence Lactase Activity Breath Hydrogen Test 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.


Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.


  1. Abbas, H., and Ahmad, M., 1983, Persistence of high intestinal lactase activity in Pakistan, Hum. Genet. 64: 277–278.PubMedGoogle Scholar
  2. Ahmad, M., and Flatz, G., 1984, Prevalence of primary adult lactose malabsorption in Pakistan, Hum. Hered. 34: 69–75.PubMedGoogle Scholar
  3. Ahmed, H. F., 1975, Irritable-bowel syndrome and lactose intolerance, Lancet 2: 319–320.PubMedGoogle Scholar
  4. Alford, S. C., 1969, Lactose intolerance in Asians, Nature 221: 562–567.PubMedGoogle Scholar
  5. Alhava, E. M., Jussila, J., Karjalainen, P., and Vuojolahti, P., 1977, Lactose malabsorption and bone mineral content, Acta Med. Scand. 201: 281–283.PubMedGoogle Scholar
  6. Alun Jones, V., McLaughlan, P., Shorthouse, N., Workman, E., and Hunter, J. O., 1982, Food intolerance: A major factor in the pathogenesis of irritable bowel syndrome, Lancet 2: 1115–1117.PubMedGoogle Scholar
  7. Alzate, H., Ramirez, E., and Echeverria, M. T., 1968, Intolerancia a la lactosa en un grupo de estudiantes de medicina, Antioquia Med. 18: 237–246.Google Scholar
  8. Alzate, H., Gonzalez, H., and Guzman, I., 1969, Lactose intolerance in South American Indians, Am. J. Clin. Nutr. 22: 122–123.PubMedGoogle Scholar
  9. American Academy of Pediatrics, 1974, Committee on Nutrition (M. A. Holliday, chairman), Should milk drinking by children be discouraged?, Pediatrics 53: 576–582.Google Scholar
  10. Ammerman, A. J., and Cavalli-Sforza, L. L., 1971, Measuring the rate of spread of early farming in Europe, Man 6: 674–688.Google Scholar
  11. Anh, N. T., Thuc, T. K., and Welsh, J. D., 1977, Lactose malabsorption in adult Vietnamese, Am. J. Clin. Nutr. 30: 468–469.PubMedGoogle Scholar
  12. Anonymous, 1984, In vivo digestion of yogurt lactose by yogurt lactase, Nutr. Rev. 42: 216–218.Google Scholar
  13. Antonowicz, I., and Lebenthal, E., 1977, Developmental pattern of small intestinal enterokinase and disaccharidase activities in the human fetus, Gastroenterology 72: 1299–1303.PubMedGoogle Scholar
  14. Arnhold, R. G., Perman, J. A., and Nurse, G. T., 1981, Persistent high intestinal lactase activity in Papua-New Guinea, Ann. Hum. Biol. 8: 481–484.PubMedGoogle Scholar
  15. Arnold, J., Diop, M., Kodjovi, M., and Rozier, J., 1980, L’intolerance au lactose chez l’adulte au Senegal, C. R. Soc. Biol. 174: 983–992.Google Scholar
  16. Arola, H., Koivula, T., Jokela, H., and Isokoski, M., 1982, Simple urinary test for lactose malabsorption, Lancet 2: 524–525.PubMedGoogle Scholar
  17. Arrigo, L., Ciangarotti, S., Lantiere, P. B., Capponetto, A., Rovida, S., Bozzatti, D., DeToni, T., and Duillo, M. T., 1980, Indagine epidemiologica sul grado di incidenza dell’ippolattasia e dell’ intoleranza al lattosio, in campioni di populazione adulta e pediatrica, in Liguria, Rev. Soc. Ital. Sci. Aliment. 9: 391–400.Google Scholar
  18. Asp, N. G., and Dahlqvist, A., 1972, Human small intestinal disaccharidases. Specific assay of three different enzymes, Anal. Biochem. 47: 527–538.PubMedGoogle Scholar
  19. Asp, N. G., Berg, N. O., Dahlqvist, A., Jussila, J., and Salmi, H., 1971, The activity of three different small-intestinal 3-galactosidases in adults with and without lactase deficiency, Scand. J. Gastroenterol. 6: 755–762.PubMedGoogle Scholar
  20. Asp, N. G., Berg, N. O., Dahlqvist, A., Gudmand-H¢yer, E., Jarnum, E., and McNair, A., 1975, Intestinal disaccharidases in Greenland Eskimos, Scand. J. Gastroenterol. 10: 513–519.Google Scholar
  21. Au, W. Y. W., and Raisz, L. G., 1967, Restoration of parathyroid responsiveness in Vitamin-D-deficient rats by parenteral calcium or dietary lactose, J. Clin. Invest. 46: 1572–1578.Google Scholar
  22. Auricchio, S., Rubino, A., Semenza, G., Landolt, M., and Prader A., 1963, Isolated intestinal lactase deficiency in the adult, Lancet 2: 324–326.PubMedGoogle Scholar
  23. Auricchio, S., Rubino, A., and Mürset, G., 1965, Intestinal glycosidase activities in the human embryo, fetus and newborn, Pediatrics 35: 944–948.PubMedGoogle Scholar
  24. Balanza, E., and Taboada, G., 1985, The frequency of lactase phenotypes in Aymara children, J. Med. Genet. 22: 128–130.PubMedGoogle Scholar
  25. Bartholomew, C., and Pong, O. Y., 1976, Lactose intolerance in East Indians of Trinidad, Trop. Geogr. Med. 28: 336–338.PubMedGoogle Scholar
  26. Bayless, T. M., and Rosensweig, N. S., 1966, A racial difference in the incidence of lactase deficiency. A survey of milk intolerance and lactase deficiency in healthy adult males, J. Am. Med. Assoc. 197: 968–972.Google Scholar
  27. Bayless, T. M., Christopher, N. L., and Boyer, S. H., 1969, Autosomal recessive inheritance of intestinal lactase deficiency: Evidence from ethnic differences, J. Clin. Invest. 48: 6a.Google Scholar
  28. Bayless, T. M., Rothfeld, B., Massa, C., Wise, L., Paige, D. M., and Bedine, M., 1975, Lactose and milk intolerance: Clinical implications, N. Engl. J. Med. 292: 1156–1159.PubMedGoogle Scholar
  29. Bayoumi, R. A. L., Saha, N., Salih, A. S., Bakkar, A. E., and Flatz, G., 1981, Distribution of the lactase phenotypes in the population of the Democratic Republic of the Sudan, Hum. Genet. 57: 279–281.PubMedGoogle Scholar
  30. Bayoumi, R. A. L., Flatz, S. D., Kühnau, W., and Flatz, G.. 1982, Beja and Nilotes: Nomadic pastoralist groups in the Sudan with opposite distributions of the adult lactase phenotypes, Am. J. Phys. Anthropol. 58: 173–178.PubMedGoogle Scholar
  31. Bedine, M. S., and Bayless, T., M., 1973, Intolerance of small amounts of lactose by individuals with low lactase levels, Gastroenterology 65: 735–743.PubMedGoogle Scholar
  32. Bennet, A., and Eley, K. G., 1976, Intestinal pH and propulsion: An explanation of diarrhoea in lactase deficiency and laxation by lactulose, J. Pharm. Pharmacol. 28: 192–195.Google Scholar
  33. Birge, S. J., Keutmann, H. T., Cuatrecasas, P., and Whedon, G. D., 1967, Osteoporosis, intestinal lactase deficiency and low dietary calcium intake, N. Engl. J. Med. 276: 445448.Google Scholar
  34. Blaxter, K. L., 1961, Lactation and the growth of the young, in: Milk: The Mammary Gland and Its Secretion ( S. K. Kow and A. T. Cowie, eds.), pp. 329–338, Academic Press, New York.Google Scholar
  35. Bolin, T. D., and Davis, A. E., 1969, Asian lactose intolerance and its relation to intake of lactose, Nature 222: 382–383.PubMedGoogle Scholar
  36. Bolin, T. D., and Davis, A. E., 1970a, Primary adult lactase deficiency: Genetic or acquired?, Am. J. Dig. Dis. 15: 692–769.Google Scholar
  37. Bolin, T. D., and Davis, A. E., 1970b, Lactose intolerance in Australian-born Chinese, Australas. Ann. Med. 19: 40–41.PubMedGoogle Scholar
  38. Bolin, T. D., Crane G. G., and Davis, A. E., 1968, Lactose intolerance in various ethnic groups in Southeast Asia, Australas. Ann. Med. 17: 300–306.PubMedGoogle Scholar
  39. Bolin, T. D., Pirola, R. C., and Davis, A. E., 1969, Adaptation of intestinal lactase in the rat, Gastroenterology 60: 432–437.Google Scholar
  40. Bolin, T. D., Davis, A. E., Seah, C. S., Chua, K. L., Yong, V., Kho, K. M., Siak, C. L., and Jacob, E., 1970a, Lactose intolerance in Singapore, Gastroenterology 59: 76–84.PubMedGoogle Scholar
  41. Bolin, T. D., Morrison, R. N., Steel, G. E., and Davis, A. E., 19706. Lactose intolerance in Australia, Med. J. Aust. 1: 1289–1292.Google Scholar
  42. Bond, J. H., and Levitt, M. D., 1972, Use of pulmonary hydrogen (H2) measurements to quantitate carbohydrate absorption: Study of partially gastrectomized patients, J. Clin. Invest. 51: 1219–1225.PubMedGoogle Scholar
  43. Bond, J. H., and Levitt, M. D., 1976a, Quantitative measurement of lactose absorption, Gastroenterology 70: 1058–1062.PubMedGoogle Scholar
  44. Bond, J. H., and Levitt, M. D., 19766, Fate of soluble carbohydrate in the colon of rats and man, J. Clin. Invest. 57: 1158–1164.Google Scholar
  45. Bond, J. H., Engel, R. R., and Levitt, M. D., 1971, Factors influencing pulmonary methane excretion in man: An indirect method of studying the in situ metabolism of methane producing colonic bacteria, J. Exp. Med. 133: 572–588.PubMedGoogle Scholar
  46. Bose, D. P., and Welsh, J. D., 1973, Lactose malabsorption in Oklahoma Indians, Am. J. Clin. Nutr. 26: 1320–1322.PubMedGoogle Scholar
  47. Brand, J. C., Gracey, M.S., Randolf, M. S., and Dutton, S. P., 1983, Lactose malabsorption in Australian aborigines, Am. J. Clin. Nutr. 37:449–452.Google Scholar
  48. Brew, K., Vanaman, T. C., and Hill, R. L., 1968, The role of alpha-lactalbumin and the A protein in lactose synthetase: A unique mechanism for the control of a biological reaction, Proc. Natl. Acad. Sci. USA 59: 491–496.PubMedGoogle Scholar
  49. Bryant, G. D., Chu, Y. K., and Lovitt, R., 1970, Incidence and aetiology of lactose intolerance, Med. J. Aust. 1: 1285–1288.PubMedGoogle Scholar
  50. Buisseret, P. D., Youlten, L. Y. F., Heinzelmann, D. I., and Lassof, M. H., 1978, Pros- taglandin-synthesis inhibitors in prophylaxis of food intolerance, Lancet 1: 906–909.PubMedGoogle Scholar
  51. Burgio, G. R., Flatz, G., Barbera, C., Patane, R., Boner, A., Cajozzo, C., and Flatz, S. D., 1984, Prevalence of primary adult lactose malabsorption and awareness of milk intolerance in Italy, Am. J. Clin. Noir. 39: 100–104.Google Scholar
  52. Busk, H. E., Dahlerup, B., Lythen, T., Binder, V., and Gudmand-Hóyer, E., 1975, The incidence of lactose malabsorption -in ulcerative colitis, Scand. J. Gastroenterol. 10: 163–165.Google Scholar
  53. Calderon-Viacava, L., Cozorla-Talleri, A., and Leon-Barua, R., 1971. Incidenzia de malabsorcion de lactosa en jovenes peruanos sanos, Acta Gastroenterol. Latinoam. 3: 1116.Google Scholar
  54. Calloway, D. H., Colasito, D. J., and Mathews, R. D., 1966, Gases produced by human intestinal microflora, Nature 212: 1238–1239.PubMedGoogle Scholar
  55. Calloway, D. H., Murphy, E. L., and Bauer, D., 1969, Determination of lactose intolerance by breath analysis. Am. J. Dig. Dis. 14: 811–815.PubMedGoogle Scholar
  56. Caskey, D. A., Payne-Bose, D., Welsh, J. D., Gearhart, H. L., Nance, M. K., and Morrison, R. D., 1977, Effects of age on lactose malabsorption in Oklahoma native Americans as determined by breath H2 analysis, Am. J. Dig. Dis. 22: 113–116.PubMedGoogle Scholar
  57. Cavalli-Sforza, L. L., 1973, Analytical review: Some current problems of human population genetics, Am. J. Hum. Genet. 25: 82–104.PubMedGoogle Scholar
  58. Christopher, N. L., and Bayless, T. M., 1971, Role of the small bowel and colon in lactose induced diarrhea, Gastroenterology 70: 845–852.Google Scholar
  59. Chua, K. L., and Seah, C. S., 1973, Lactose intolerance: Hereditary or acquired? Effect of prolonged milk feeding, Singapore Med. J. 14: 29–33.PubMedGoogle Scholar
  60. Chung, M. H., and McGill, D. B., 1968, Lactase deficiency in Orientals, Gastroenterology 54: 225–226.PubMedGoogle Scholar
  61. Cochet, B., Jung, A., Griessen, M., Bartholdi, P., Schaller, P., and Donath, A., 1983, Effects of lactose on intestinal calcium absorption in normal and lactase deficient subjects, Gastroenterology 84: 935–940.PubMedGoogle Scholar
  62. Cook, G. C., 1973, Incidence and clinical features of specific hypolactasia in man, in: Intestinal Enzyme Deficiencies and Their Nutritional Implications ( M. Borgström, A. Dahlqvist, and L. Hambraeus, eds.), pp. 52–73, Almqvist and Wiksell, Stockholm.Google Scholar
  63. Cook, G. C., 1978, Did persistence of intestinal lactase into adult life originate in the Arabian paninsula?, Man 13: 418–427.Google Scholar
  64. Cook, G. C., 1979, Intestinal lactase status of adults in Papua-New Guinea, Ann. Hum. Biol. 6: 55–58.PubMedGoogle Scholar
  65. Cook, G. C., and Al-Torki, M. T., 1975, High intestinal lactase concentration in adult Arabs in Saudi Arabia, Br. Med. J. 3: 135–136.PubMedGoogle Scholar
  66. Cook, G. C., and Dahlqvist, A., 1968, Jejunal hetero-(3-galactosidase activities in Ugandans with lactase deficiency, Gastroenterology 55: 328–332.PubMedGoogle Scholar
  67. Cook, G. C., and Kajubi, S. K., 1966, Tribal incidence of lactase deficiency in Uganda, Lancet 1: 725–729.PubMedGoogle Scholar
  68. Cook, G. C., Lakin, A., and Whitehead, R. G., 1967, Absorption of lactose and its digestion products in the normal and malnourished Ugandan, Gut 8: 622–627.PubMedGoogle Scholar
  69. Cook, G. C., Asp, N. G., and Dahlqvist, A., 1973, Activities of brush border lactase, acid 3-galactosidase and hetero- 3-galactosidase in the jejunum of the Zambian African, Gastroenterology 64: 405–410.PubMedGoogle Scholar
  70. Cox, J. A., and Elliott, F. G., 1974, Primary adult lactose intolerance in the Kivu lake area: Rwanda and the Bushi, Am. J. Dig. Dis. 19: 714–724.PubMedGoogle Scholar
  71. Cuatrecasas, P. D., Lockwood, H., and Caldwell, J., 1965, Lactase defiency in the adult: A common occurrence, Lancet 1: 14–18.PubMedGoogle Scholar
  72. Cuddenec, Y., Delbrück, H., and Flatz, G., 1982, Distribution of the adult lactase phenotypes—lactose absorber and malabsorber—in a group of 131 army recruits, Gastroenterol. Clin. Biol. 6: 776–779.PubMedGoogle Scholar
  73. Currie, B., Nurse, G. T., and Jenkins, T., 1978, Low frequency of persistent high intestinal lactase activity (lactose tolerance) in the Herero, S. Afr. J. Sci. 74: 227–228.Google Scholar
  74. Czeizel, A., Flatz, G., and Flatz S. D., 1983, Prevalence of primary adult lactose malabsorption in Hungary, Hum. Genet. 64: 398–401.PubMedGoogle Scholar
  75. Dahlqvist, A., 1961, Determination of maltase and isomaltase activities with a glucose oxidase reagent, Biochem. J. 80: 547–551.PubMedGoogle Scholar
  76. Dahlqvist, A., 1974, Enzyme deficiency and malabsorption of carbohydrates, in: Sugars in Nutrition ( H. L. Sipple and K. W. McNutt, eds.), pp. 187–214, Academic Press, New York.Google Scholar
  77. Dahlqvist, A., 1977, The basic aspects of the chemical background of lactase deficiency, Postgrad. Med. J. 53: 57–64.Google Scholar
  78. Dahlqvist, A., 1984, Assay of intestinal disaccharidases, Scand. J. Clin. Lab. Invest. 44: 169–172.PubMedGoogle Scholar
  79. Dahlqvist, A., and Borgström, B., 1961, Digestion and absorption of disaccharides in man, Biochem. J. 81: 411–418.PubMedGoogle Scholar
  80. Dahlqvist, A., and Brun, A., 1962, A method for the histochemical demonstration of disaccharidase activities: Application to invertase and trehalase in some animal tissues, J. Histochem. Cytochem. 10: 294–302.Google Scholar
  81. Dahlqvist, A., and Lindberg, T., 1966, Development of the intestinal disaccharidase and alkaline phosphatase activities in the human fetus, Clin. Sci. 30: 507–512.Google Scholar
  82. Dahlqvist, A., and Lindquist, B., 1971, Lactose intolerance and protein malnutrition, Acta Paediatr. Scand. 60: 488–494.PubMedGoogle Scholar
  83. Dahlqvist, A., and Nordström, C., 1966, The distribution of disaccharidase activities in the villi and crypts of the small-intestinal mucosa, Biochim. Biophys. Acta 113: 624–626.PubMedGoogle Scholar
  84. Dahlqvist, A., Hammond, B., Crane, R. K., Dunphy, J. V., and Littman, A., 1963, Intestinal lactase deficiency and lactose intolerance in adults: Preliminary report, Gastroenterology 45: 488–491.PubMedGoogle Scholar
  85. Debongnie, J. C., Newcomer, A. D., Millard, J. C., Hilbe, A., and Stainthorpe, E. M., 1979, Absorption of nutrients in lactase deficiency, Dig. Dis. Sci. 24: 225–231.Google Scholar
  86. Desai, H. G., Chitre, A. V., and Jeejeebhoy, K. N., 1967, Lactose loading, Gastroenterologia 108: 177–188.PubMedGoogle Scholar
  87. Desai, H. G., Gupte, U. V., Pradhan, A. G., Thakkar, K. D., and Antia, F. P., 1970, Incidence of lactase deficiency in control subjects from India, Indian J. Med. Sci. 24: 729–736.PubMedGoogle Scholar
  88. Dill, J. E., Levy, M., Wells, R. F., and Weser, E., 1972, Lactase deficiency in Mexican-American males, Am. J. Clin. Nutr. 25: 869–870.PubMedGoogle Scholar
  89. Doell, R. G., and Kretchmer, N., 1962, Studies of small intestine during development. I. Distribution and activity of p-galactosidases, Biochim. Biophys. Acta 62: 353–362.PubMedGoogle Scholar
  90. Doxiadis, S., and Papageorgiadis, G., 1973, Lactose intolerance in Greeks, Lancet 1: 271.PubMedGoogle Scholar
  91. Dragstedt, L. R., and Peacock, S. C., 1923, Studies on the pathogenesis of tetany. The control of parathyroid tetany by diet, Am. J. Physiol. 64: 424–434.Google Scholar
  92. Duarte, E., and Dutra de Oliveira, J. E., 1978, Intolerancia a lactose em adultos, Rev. Bras. Pesqu. Med. Biol. 11: 105–109.Google Scholar
  93. Duncan, J. W., and Scott, E. M., 1972, Lactose intolerance in Alaskan Indians and Eskimos, Am. J. Clin. Nutr. 25: 867–868.PubMedGoogle Scholar
  94. Dunphy, J. V., Littman, A., Hammond, B., Forstner, G., Dahlqvist, A., and Crane, R. K., 1965, Intestinal lactase deficit in adults, Gastroenterology 49: 12–21.Google Scholar
  95. Durham, W. H., 1980, The interaction of biology and culture: A case study of dairying, Annual Meeting, American Anthropological Association.Google Scholar
  96. Elliot, F. G., Cox, J., and Nyomba, B. C., 1973, Intolerance au lactose chez l’adulte en Afrique centrale, Ann. Soc. Belg. Med. Trop. 55: 113–132.Google Scholar
  97. El-Schallah, M. O., Rotthauwe, H. W., and Flatz, G., 1973, Laktose-Intoleranz in der arabischen Bevölkerung, Med. Welt 24: 1376–1377.PubMedGoogle Scholar
  98. Ferguson, A., and Maxwell, J., 1967, Genetic aetiology of lactose intolerance, Lancet 2: 188–190.PubMedGoogle Scholar
  99. Fielding, J. F., Harrington, M. G., and Fottrell, P. F., 1981, The incidence of primary hypolactasia among the Irish, Ir. J. Med. Sci. 150: 276–277.PubMedGoogle Scholar
  100. Figueroa, R. B., Melgar, E., Jo, N., and Garcia, O. L., 1971, Intestinal lactase deficiency in an apparently normal Peruvian population, Am. J. Dig. Dis. 16: 881–889.PubMedGoogle Scholar
  101. Fischer, J. E., 1957, Effects of feeding a diet containing lactose upon 3-D-galactosidase activity and organ development in the rat digestive tract, Am. J. Physiol. 188: 49–53.PubMedGoogle Scholar
  102. Fischer, W., and Zapf, J., 1965, Zur erworbenen Laktoseintoleranz, Klin. Wochenschr. 43: 1243–1246.PubMedGoogle Scholar
  103. Flatz, G., 1977, Lactose tolerance: Genetics, anthropology and natural selection, in: Proceedings Vth International Congress Human Genetics, Mexico City, 1976 ( S. Armen-dares and R. Lisker, eds.), pp. 386–396, Excerpta Medica, Amsterdam.Google Scholar
  104. Flatz, G., 1984a, Gene dosage effect on lactase activity demonstrated in vivo, Am. J. Hum. Genet. 36: 306–310.PubMedGoogle Scholar
  105. Flatz, G., 1984b, Laktase-Phänotypen in sesshaften und nomadischen Bevölkerungsgruppen des Nahen Ostens, Homo 35: 173–178.Google Scholar
  106. Flatz, G., 1986, Lactase deficiency, in: The Genetics of Common Disease (R. A. King, J. I. Rotter, and A. G. Motulsky, eds.), Chapter 20, McGraw-Hill, New York.Google Scholar
  107. Flatz, G., and Rotthauwe, H. W., 1971, Evidence against nutritional adaptation of tolerance to lactose, Hum. Genet. 13: 118–125.Google Scholar
  108. Flatz, G., and Rotthauwe, H. W., 1973, Lactose nutrition and natural selection, Lancet 2: 76–77.PubMedGoogle Scholar
  109. Flatz, G., and Rotthauwe, H. W., 1977, The human lactase polymorphism: Physiology and genetics of lactose absorption and malabsorption, Progr. Med. Genet. (New Series) 2: 205–249.Google Scholar
  110. Flatz, G., and Saengudom, C., 1969, Lactose tolerance in Asians: A family study, Nature 224: 915–916.PubMedGoogle Scholar
  111. Flatz, G., Saengudom, C., and Sanguanbhokhai, T., 1969, Lactose intolerance in Thailand, Nature 221: 758–759.PubMedGoogle Scholar
  112. Flatz, G., Bernsau, I., and Behrens, A., 1982a, Lactose absorption and malabsorption in healthy German children: Improved phenotypic resolution by simultaneous determination of breath hydrogen and carbon dioxide, Eur. J. Pediatr. 138: 304–306.PubMedGoogle Scholar
  113. Flatz, G., Howell, J. N., Doench, J., and Flatz, S. D., 1982b, Distribution of physiological adult lactase phenotypes, lactose absorber and malabsorber, in Germany, Hum. Genet. 62: 152–157.Google Scholar
  114. Flatz, G., Kühnau, W., and Naftali, D., 1984, Breath hydrogen test for lactose absorption capacity: Importance of timing of hydrogen excretion and of high fasting hydrogen concentration, Am. J. Clin. Nutr. 39: 752–755.PubMedGoogle Scholar
  115. Flatz, G., Czeizel, A., Metneki, J., Flatz, S. D., Kühnau, W., and Jahn, D., 1985, Pulmonary hydrogen and methane excretion following the ingestion of an unabsorbable carbohydrate: A study of twins, J. Pediatr. Gastroenterol. 4: 936–941.Google Scholar
  116. Flatz, G., Schildge, C., and Sekou, H., 1986a, Distribution of adult lactase phenotypes in the Tuareg of Niger, Am. J. Hum. Genet. 38: 515–520.PubMedGoogle Scholar
  117. Flatz, G., Henze, H. J., Palabiyikoglu, E., Dagalp, K., and Türkkan, T., 1986b, Distribution of the adult lactase phenotypes in Turkey, Trop. Geogr. Med. 38: 255–258.PubMedGoogle Scholar
  118. Fournier, P., and Dupuis, Y., 1960, Pouvoir antirachitique de composes divers, dits de structure: lactose, glucosamine, L-xylose, mannitol, C. R. Acad. Sci. Paris 250: 3050–3052.Google Scholar
  119. Gibney, S. F. A., Munroe, V., Nurse, G. T., and Schofield, E. C., 1981, Lactose absorption in a western Massim population, Ann. Hum. Biol. 8: 477–480.PubMedGoogle Scholar
  120. Gilat, T., Kuhn, R., Gelman, E., and Mizrahy, O., 1970, Lactase deficiency in Jewish communities in Israel, Atn. J. Dig. Dis. 15: 895–904.Google Scholar
  121. Gilat, T., Russo, S., Gelman-Malachi, E., and Aldor, T. A. M., 1972, Lactase in man: A nonadaptable enzyme, Gastroenterology 62: 1125–1127.PubMedGoogle Scholar
  122. Gilat, T., Benaroya, Y., Gelman-Malachi, E., and Adam, A., 1973, Genetics of primary adult lactase deficiency, Gastroenterology 64: 562–568.PubMedGoogle Scholar
  123. Goda, T., Bustamente, S., Thornburg, W., and Koldovsky, O., 1984, Dietary-induced increase in lactase activity and in immunoreactive lactase in adult rat jejunum, Biochern. J. 221: 261–263.Google Scholar
  124. Graham, G. G., 1975, Protein Advisory Group’s recommendations deplored, Pediatrics 55: 295–296.PubMedGoogle Scholar
  125. Gray, G. M., and Santiago, N. A., 1966, Disaccharide absorption in normal and diseased human intestine, Gastroenterology 51: 489–498.PubMedGoogle Scholar
  126. Gray, G. M., and Santiago, N. A., 1969, Intestinal 3-galactosidases. I. Separation and characterization of three enzymes in normal human intestine, J. Clin. Invest. 48: 716–728.PubMedGoogle Scholar
  127. Gray, G. M., Santiago, N. A., Colver, E. H., and Gene!. M., 1969, Intestinal 3-galactosidases. Il. Biochemical alteration in human lactase deficiency, J. Clin. Invest. 48: 729–735.PubMedGoogle Scholar
  128. Greenwald, E., Samachson, S., and Spencer, H., 1963, Effect of lactose on calcium metabolism in man, J. Nutr. 79: 531–538.PubMedGoogle Scholar
  129. Gudmand-H¢yer, E., and Jarnum, S., 1969, Lactose malabsorption in Greenland Eskimos, Acta Med. Scand. 186: 235–237.Google Scholar
  130. Gudmand-Hpyer, E., and Simony, K., 1977, Individual sensitivity to lactose in lactose malabsorption, Am. J. Dig. Dis. 22: 177–181.Google Scholar
  131. Gudmand-Hßyer, E., Dahlqvist, A., and Jarnum, S., 1969, Specific small-intestinal lactase deficiency in adults, Scand. J. Gastroenterol. 4: 377–386.Google Scholar
  132. Gudmand-HOyer, E., McNair, A., Jarnum, S., Broersma, L., and McNair, J., 1973, Laktosemalabsorption in Vestgr¢nland, Ugeskr. Laeg. 135: 169–172.PubMedGoogle Scholar
  133. Guin, B., Duchier, J., Chariot, J, Cerf, M., and Debray, C., 1972, Le probleme de l’intolerance au lactose chez l’adulte, Ann. Med. Interne 123: 145–154.Google Scholar
  134. Gupta, P. S., Misra, R. C., Ramachandran, K. A., and Chuttani, H. K., 1970, Lactose intolerance in adults, J. Assoc. Physicians India 18: 765–768.PubMedGoogle Scholar
  135. Gupta, P. S., Misra, R. C., Ramachandran, K. A., Sarin, G. S., and Chuttani, H. K., 1971, Intestinal disaccharidase activity in normal adult population in tropics, J. Trop. Med. Hyg. 74: 225–229.PubMedGoogle Scholar
  136. Habte, D., Sterky, G., and Hjalmarsson, B., 1973, Lactose malabsorption in Ethiopean children, Acta Paediatr. Scand. 62: 649–654.PubMedGoogle Scholar
  137. Haemmerli, U., Kistler, H., Amman, R., Marthaler, R., Semenza, G., Auricchio, S., and Prader, A., 1965, Acquired milk intolerance in the adult caused by lactose malabsorption due to selective deficiency of intestinal lactase activity, Am. J. Med. 38: 7–30.PubMedGoogle Scholar
  138. Halstead, C. H., Sheir, S., Sourial, N., and Pathwardan, V. N., 1969, Small intestinal structure and absorption in Egypt, Am. J. Clin. Nutr. 22: 744–754.Google Scholar
  139. Hasunen, K., Muhonen, M., Sahi, T., and Kirjarinta, M., 1977, Dietary intake in cases of lactose malabsorption in a Finnish Lapp population, Nordic Council Arct. Med. Res. 17: 3–20.Google Scholar
  140. Heading, R. C., 1982, Gastric emptying: A clinical perspective, Clin. Sci. 63: 231–235.PubMedGoogle Scholar
  141. Hijazi, S. S., Abulaban, A., Ammarin, Z., and Flatz, G., 1983, Distribution of adult lactase phenotypes in Bedouins and in urban and agricultural populations of Jordan, Trop. Geogr. Med. 35: 157–161.PubMedGoogle Scholar
  142. Ho, M. W., Povey, S., and Swallow, D., 1982, Lactase polymorphism in adult British natives: Estimating allele frequencies by enzyme assays in autopsy samples, Am. J. Hum. Genet. 34: 650–657.PubMedGoogle Scholar
  143. Holzel, A., Schwarz, V., and Sutcliffe, A. W., 1959, Defective lactose absorption causing malnutrition in infancy, Lancet 1: 1126–1128.PubMedGoogle Scholar
  144. Howell, J. N., Melimann, J., Ehlers, P., and Flatz, G., 1980, Intestinal disaccharidase activities and activity ratios in a group of 60 adult German subjects, Hepato-Gastroenterol. 27: 208–212.Google Scholar
  145. Howell, J. N., Schockenhoff, T., and Flatz, G., 1981, Population screening for the human adult lactase phenotypes with a multiple breaths version of the breath hydrogen test, Hum. Genet. 57: 276–278.PubMedGoogle Scholar
  146. Howland, J., 1921, Prolonged intolerance to carbohydrates, Trans. Am. Pediatr. Soc. 33: 1119.Google Scholar
  147. Huang, S. S., and Bayless, T. M., 1968, Milk and lactose intolerance in healthy Orientals, Science 160: 83–84.PubMedGoogle Scholar
  148. Hussein, L., Flatz, S. D., Kühnau, W., and Flatz, G., 1982, Distribution of human adult lactase phenotypes in Egypt, Harn. Hered. 32: 94–99.Google Scholar
  149. Isokoski, M., Jussila, J., and Sarna, S., 1972, A simple screening method for lactose malabsorption, Gastroenterology 62: 28–32.PubMedGoogle Scholar
  150. Isokoski, M., Sahi, T., Villako, K., and Tamm, A., 1981, Epidemiology and genetics of lactose malabsorption, Ann. Clin. Res. 13: 164–168.PubMedGoogle Scholar
  151. Jenkins, T., Lehmann, H., and Nurse, G. T., 1974, Public health and genetics of the San (Bushmen): Carbohydrate metabolism and acetylator status of the !Kung of Tsumkwe in the northwestern Kalahari, Br. Med. J. 2: 23–26.PubMedGoogle Scholar
  152. Jenkins, T., Gibney, S. F. A., Nurse, G. T., and Penketh, R. J. A., 1981, Persistent high intestinal lactase activity in Papua-New Guinea. Lactose absorption curves in two populations, Ann. Hum. Biol. 8: 447–451.PubMedGoogle Scholar
  153. Jersky, J., and Kinsley, R. H., 1967, Lactase deficiency in the South African Bantu, S. Afr. Med. J. 41: 1194–1196.PubMedGoogle Scholar
  154. Johnson, J. D., Kretchmer, N., and Simoons, F. J., 1974, Lactose malabsorption: Its biology and history, Adv. Pediatr. 21: 197–237.PubMedGoogle Scholar
  155. Johnson, J. D., Simoons, F. J., Hurwitz, R., Grange, A., Mitchell. C. H., Sinatra, F. R., Sunshine, P., Robertson, W. F., Bennett, T. H., and Kretchmer, N., 1977, Lactose malabsorption among the Pima Indians of Arizona, Gastroenterology 73: 1299–1304.PubMedGoogle Scholar
  156. Johnson, J. D., Simoons, F. J., Hurwitz, R., Grange, A., Sinatra, F. R., Sunshine, P., Robertson, W. F., Bennett, T. H., and Kretchmer, N., 1978, Lactose malabsorption among adult Indians of the Great Basin and American Southwest. Am. J. Clin. Nutr. 31: 381–387.PubMedGoogle Scholar
  157. Jonas, M. M., Montgomery, R. K., and Grand, R. J., 1985, Intestinal lactase synthesis during postnatal development in the rat, Pediatr. Res. 19: 956–962.PubMedGoogle Scholar
  158. Jonxis, J. H. P., 1961, Some investigations on rickets, J. Pediatr. 59: 607–615.PubMedGoogle Scholar
  159. Jumawan, J., and Koldovsky, O., 1978, Comparison of the effect of various doses of thyroxine on jejunal disaccharidases in intact and adrenalectomized rats during the first three weeks of life, Enzyme 23: 206–209.PubMedGoogle Scholar
  160. Jussila, J., 1969a, Diagnosis of lactose malabsorption by the lactose tolerance test with peroral ethanol administration, Scand. J. Gastroenterol. 4: 361–366.PubMedGoogle Scholar
  161. Jussila, J., 19696, Milk intolerance and lactose malabsorption in hospital patients and young servicemen in Finland, Ann. Clin. Res. 1: 199–207.Google Scholar
  162. Jussila, J., Isokoski, M., and Launiala, K., 1970, Prevalence of lactose malabsorption in a Finnish rural population, Scand. J. Gastroenterol. 5: 49–56.PubMedGoogle Scholar
  163. Kanaghinis, T., Hatzioannou, J., Deliargyris, N., Danos, N., Zografos, N., Katsas, A., and Gardikas, C., 1974, Primary lactase deficiency in Greek adults, Am. J. Dig. Dis. 19: 1021–1027.PubMedGoogle Scholar
  164. Kattamis, C., Anastassea-Vlachou, K., Logothetis, N., Siriopoulou, V., and Matsaniotis, N., 1973, Lactose intolerance in Greeks, Lancet 1: 367–368.Google Scholar
  165. Kern, F., and Heller, M., 1968, Blood galactose after lactose and ethanol: An accurate index of lactase deficiency, Gastroenterology 54: 1250.Google Scholar
  166. Keusch, G. T., Troncale, F. J., Miller, L. H., Promdath, V., and Anderson, P. R., 1969a, Acquired lactose malabsorption in Thai children, Pediatrics 43: 540–545.PubMedGoogle Scholar
  167. Keusch, G. T., Troncale, F. J., Thavaramara, B., Prinyanont, P., Anderson, R. P., and Bhamarapravathi, N., 1969b, Lactase deficiency in Thailand: Effect of prolonged lactose feeding, Am. J. Clin. Nutr. 22: 638–641.PubMedGoogle Scholar
  168. Klibanov, A. M., Alberti, B. N., and Zale, S. E., 1982, Enzymatic synthesis of formic acid from H2 and CO2 and production of hydrogen from formic acid, Biotechnol. Bioeng. 24: 25–36.PubMedGoogle Scholar
  169. Knudsen, K. B., Welsh, M. D., Kronenberg, R. S., Vanderveen, J. E., and Heidelbauch, N. D., 1968, Effect of a nonlactose diet on human intestinal disaccharidase activity, Am. J. Dig. Dis. 13: 593–597.PubMedGoogle Scholar
  170. Kocian, J., Skala, I., and Bakos, K., 1973, Calcium absorption from milk and lactose free milk in healthy subjects and patients with lactase deficiency, Digestion 9: 317–324.PubMedGoogle Scholar
  171. Kolars, J. C., Levitt, M. D., Aouji, M., and Savaiano, D. A., 1984, Yogurt—An autodig-esting source of lactase, N. Engl. J. Med. 310: 1–3.PubMedGoogle Scholar
  172. Koldovsky, O., and Sunshine, P., 1970, Effect of cortisone on the developmental pattern of the neutral and the acid 3-galactosidase of the small intestine in the rat, Biochem. J. 117: 467–471.PubMedGoogle Scholar
  173. Krasilnikoff, P. A., Gudmand-H¢yer, E., and Moltke, H. H., 1975, Diagnostic value of disaccharidase tolerance tests in children, Acta Paediatr. Scand. 64: 693–698.Google Scholar
  174. Kretchmer, N., 1971, Memorial lecture: Lactose and lactase—A historical perspective, Gastroenterology 61: 805–813.PubMedGoogle Scholar
  175. Kretchmer, N., Ransome-Kuti, O., Hurwitz, R., Dungy, C., and Alakija, W., 1971, Intestinal absorption of lactose in Nigerian ethnic groups, Lancet 2: 392–395.PubMedGoogle Scholar
  176. Ladas, S., Papanikos, J., and Arapakis, G., 1982, Lactose malabsorption in Greek adults. Correlation of small bowel transit time with severity of lactose intolerance, Gut 23: 968–973.PubMedGoogle Scholar
  177. Laws, J. W., Spencer, J., and Neale, G., 1967, Radiology in the diagnosis of disaccharidase deficiency, Br. J. Radiol. 40: 594–603.PubMedGoogle Scholar
  178. Lebenthal, E., Sunshine, P., and Kretchmer, N., 1973, Effect of prolonged nursing on the activity of intestinal lactase, Gastroenterology 64: 1136–1141.PubMedGoogle Scholar
  179. Leichter, J., 1972, Lactose tolerance in a Slavic population, Am. J. Dig. Dis. 17: 73–76.PubMedGoogle Scholar
  180. Leichter, J. and Lee, M., 1971, Lactose intolerance in Canadian west coast Indians, Am. J. Dig. Dis. 16: 809–813.PubMedGoogle Scholar
  181. Leichter, J., and Tolensky, F., 1975, Effect of dietary lactose on the absorption of protein, fat and calcium in the postweaning rat, J. Nutr. 103: 392–396.Google Scholar
  182. Lembcke, B., Hönig, M., and Caspary, W. F., 1980, Different actions of neomycin and metronidazole on breath hydrogen exhalation, Z. Gastroenterol. 18: 155–160.PubMedGoogle Scholar
  183. Lengemann, F. W., Wasserman, R. H., and Comar, C. L., 1959, Studies on the enhancement of radioCa and radioSr absorption by lactose in the rat, J. Nutr. 68: 443–445.PubMedGoogle Scholar
  184. Levitt, M. D., 1969, Production and excretion of hydrogen gas in man, N. Engl. J. Med. 282: 122–127.Google Scholar
  185. Levitt, M. D., and Bond, J. H., 1970, Volume, composition and source of intestinal gas, Gastroenterology 59: 921–929.Google Scholar
  186. Levitt, M. D., and Donaldson, R. M., 1970, Use of respiratory hydrogen (H2) excretion to detect carbohydrate malabsorption, J. Lab. Clin. Med. 75: 937–945.PubMedGoogle Scholar
  187. Lieberman, M., and Lieberman, D., 1978, Lactase deficiency: A genetic mechanism which regulates the time of weaning, Am. Nat. 112: 625–627.Google Scholar
  188. Lisker, R., Lopez-Habib, G., Daltabuit, M., Rostenberg, I., and Arroyo, P., 1974, Lactase deficiency in a rural area of Mexico, Am. J. Clin. Nutr. 27: 756–759.PubMedGoogle Scholar
  189. Lisker, R., Gonzalez, B., and Daltabuit, M., 1975, Recessive inheritance of the adult type of intestinal lactase deficiency, Am. J. Hum. Genet. 227: 662–664.Google Scholar
  190. Lisker, R., Aguilar, L., and Zavala, C., 1978, Intestinal lactase deficiency and milk drinking capacity in the adult, Am. J. Clin. Nutr. 31: 1499–1503.PubMedGoogle Scholar
  191. Loiselet, J., and Jarjouhi, L., 1974, L’intolerance au lactose chez l’adulte libanais, J. Med. Liban. 27: 339–350.PubMedGoogle Scholar
  192. Lojda, Z., Fric, P., and Jodl, J., 1972, Histochemische Befunde in der Dünndarmschleimhaut bei Störungen der Kohlenhydratabsorption, Dtsch. Z. Verdau. Stoffwechskr. 32: 163167.Google Scholar
  193. Loomis, W. F., 1967, Skin-pigment regulation of vitamin-D biosynthesis in man, Science 157: 501–506.PubMedGoogle Scholar
  194. Luyken, R., Luyken-Koning, F. W. M., and Immikhuizen, T., 1971, Lactose intolerance in Surinam, Trop. Geogr. Med. 23: 54–58.PubMedGoogle Scholar
  195. MacLean, W. C., and Fink, B. B., 1980, Lactose malabsorption by premature infants: Magnitude and clinical significance, J. Pediatr. 97: 383–388.PubMedGoogle Scholar
  196. Madarovova-Nohejlova, J., 1974, Dünndarmdisaccharidaseaktivität bei Erwachsenen, Dtsch. Z. Verdau. Stoffwechselkr. 34: 229–231.Google Scholar
  197. Maandarovova-Nohejlova, J., 1982, Small bowel disaccharidase activity in Czech population and in Gipsy population living in west Bohemia, Abstract No. 1106, 7th Congress, Organisation Mondiale de Gastroenterologie, Stockholm.Google Scholar
  198. Marenco, G., Ghibaudi, D., and Meraviglia, A., 1970, Intolleranza al lattosio nell’adulto, Minerva Pediatr. 22: 505–513.PubMedGoogle Scholar
  199. Martinez-Pardo, M., Montes, P. G., Martin-Lomas, M., and Sols, A., 1979, Intestinal lactase evaluation in vivo with 3-methyllactose, FEBS Lett. 98: 99–102.PubMedGoogle Scholar
  200. Masarei, J. R. L., Sharma, P., and Jansen, A. A. J., 1972, Lactose intolerance in Fidjians and Indians, Fidji School Med. J. 7: 166–168.Google Scholar
  201. McCracken, R. D., 1971, Lactase deficiency: An example of dietary evolution, Curr. Anthropol. 12: 479–500.Google Scholar
  202. McDonald, M. J., Horowitz, R., and Duncan, T. G., 1975, Use of the lactose ethanol tolerance test in diabetics, Am. J. Med. Sci. 269: 193–199.Google Scholar
  203. McGill, D. B., and Newcomer, A. D., 1967, Comparison of venous and capillary blood samples in lactose tolerance testing, Gastroenterology 53: 371–374.PubMedGoogle Scholar
  204. McMichael, H. B., Webb, J., and Dawson, A. M., 1965, Lactase deficiency in adults: A cause of “functional” diarrhoea, Lancet 1: 717–720.PubMedGoogle Scholar
  205. Mehta, M., and Latham, M. C., 1977, Lactose intolerance in healthy adult Indians, Fed. Proc. 36: 1092.Google Scholar
  206. Mendel, L. B., and Mitchell, P. H., 1907, Chemical studies on growth. I. The inverting enzymes of the alimentary tract, especially in the embryo, Am. J. Physiol. 20: 81–96.Google Scholar
  207. Metneki, J., Czeizel, A., Flatz, S. D., and Flatz, G., 1984, A study of lactose absorption capacity in twins, Hum. Genet. 67: 296–300.PubMedGoogle Scholar
  208. Metz, G., Jenkins, D. J. A., Peters, J. J., Newman A., and Blendis L. M., 1975, Breath hydrogen as a diagnostic method for hypolactasia, Lancet 1: 1155–1157.PubMedGoogle Scholar
  209. Metz, G., Gassul, M. A., Leeds, A. R., Blendis, L. M., and Jenkins, D. J. A., 1976, A simple method for measuring breath hydrogen in carbohydrate malabsorption by end-expiratory sampling, Clin. Sci. 50: 237–240.Google Scholar
  210. Micetic-Turk, D., 1982, Prevalence of lactose malabsorption in children of north-east Slovenia, Abstract No. 1115, 7th Congress, Organisation Mondiale de Gastroenterologie, Stockholm.Google Scholar
  211. Miller, D., and Crane, R. K., 1961a, Digestive function of the epithelium of the small intestine. I. An intracellular locus of disaccharide and sugar phosphate ester hydrolysis, Biochim. Biophys. Acta 52: 281–292.PubMedGoogle Scholar
  212. Miller, D., and Crane, R. K., 1961b, Digestive function of the epithelium of the small intestine. 11. Localization of disaccharide hydrolysis in the isolated brush border portion of intestinal epithelial cells, Biochim. Biophys. Acta 52: 293–298.PubMedGoogle Scholar
  213. Murthy, M. S., and Haworth, J. C., 1970, Intestinal lactase deficiency among East Indians, Am. J. Gastroenterol. 53: 246–251.PubMedGoogle Scholar
  214. Nasrallah, S. M., 1979, Lactose intolerance in the Lebanese population and in “Mediterranean lymphoma,” Am. J. Clin. Nutr. 32: 1994–1996.PubMedGoogle Scholar
  215. Nei, M., and Saitou, N., 1986, Genetic relationship of human populations and ethnic differences in relation to drugs and food, in: Ethnic Differences in Reactions to Drugs and Other Xenohiotics (W. Kalow, H. W. Goedde, and D. P. Agarwal, eds.), pp. 21–37, Alan R. Liss, New York.Google Scholar
  216. Newcomer, A. D., and McGill, D. B., 1966, Distribution of disaccharidase activity in the small bowel of normal and lactase-deficient subjects, Gastroenterology 51: 481–488.PubMedGoogle Scholar
  217. Newcomer, A. D., and McGill, D. B., 1967, Disaccharidase activity in the small intestine: Prevalence of lactase deficiency in 100 subjects, Gastroenterology 53: 881–889.PubMedGoogle Scholar
  218. Newcomer, A. D., McGill, D. B., Thomas, P. J., and Hofmann, A. F., 1975, Prospective comparison of indirect methods for detecting lactase deficiency, N. Engl. J. Med. 293: 1232–1236.PubMedGoogle Scholar
  219. Newcomer, A. D., Thomas, P. J., McGill, D. B., and Hofmann, A. F., 1977, Lactase deficiency: A common genetic trait of the American Indian, Gastroenterology 72: 234–237.PubMedGoogle Scholar
  220. Newcomer, A. D., Hodgson, S. F., McGill, D. B., and Thomas, P. J., 1978, Lactase deficiency: Prevalence in osteoporosis, Ann. Intern. Med. 89: 218–220.PubMedGoogle Scholar
  221. Niu, H. C., Schoeller, D. A., and Klein, P. D., 1979, Improved gas chromatographic quantitation of breath hydrogen by normalization to respiratory carbon dioxide, J. Lab. Clin. Med. 94: 755–763.PubMedGoogle Scholar
  222. Nordstrom, C., and Dahlqvist, A., 1973, Quantitative distribution of some enzymes along the villi and crypts of human small intestine, Scand. J. Gastroenterol. 8: 407–416.Google Scholar
  223. Norlund, P., 1937, Wikingersiedlungen in Grönland: Ihre Entstehung und ihr Schicksal, Fischer, Leipzig.Google Scholar
  224. Nose, O., Iida, Y., Kai, H., Harada, T., Ogawa, M., and Yabuchi, H., 1979, Breath hydrogen test for detecting lactose malabsorption in infants and children, Arch. Dis. Child. 54: 436–440.PubMedGoogle Scholar
  225. Nurse, G. T., and Jenkins, T., 1974, Lactose intolerance in San populations, Br. Med. J. 2: 728.PubMedGoogle Scholar
  226. O’Keefe, S. J. D., Adam, J. K., Cakata, E., and Epstein, S., 1984, Nutritional support of malnourished lactose intolerant African patients, Gut 25: 942–947.PubMedGoogle Scholar
  227. Olatun-Bosun, D. A., and Adadevoh, B. K., 1971, Lactase deficiency in Nigerians, Am. J. Dig. Dis. 16: 909–914.Google Scholar
  228. O’Morain, C., Loubiere, M., Rampal, P., Sudaka, P., and Delmont, J., 1978, Étude comparative de l’insuffisance en lactase de deux populations adultes differentes (55 Nicois et 55 Maghrebins), Acta Gastroenterol. Belg. 41: 56–63.PubMedGoogle Scholar
  229. Paige, D. M., Bayless, T. M., Ferry, G. D., and Graham, G. G., 1971, Lactose malabsorption and milk rejection in Negro children, Johns Hopkins Med. J. 129: 163–169.PubMedGoogle Scholar
  230. Paige, D. M., Bayless, T. M., and Dellinger, W. S., 1975, Relationship of milk consumption to blood glucose rise in lactose intolerant individuals, Am. J. Clin. Noir. 28: 677–680.Google Scholar
  231. Paigen, K., 1977, Temporal genes and developmental programs, in: Human Genetics, Proceedings of the Fifth International Congress of Human Genetics, Mexico City, 10–15 October 1976 ( S. Armendares and R. Lisker, eds.), pp. 31–42, Excerpta Medica, Amsterdam.Google Scholar
  232. Pansu, D., and Chapuy, M. C., 1970, Calcium absorption enhanced by lactose and xylose, Calif Tiss. Res. 4 (Suppl.): 155–156.Google Scholar
  233. Pansu, D., Bellaton, C., and Bronner, F., 1979, Effect of lactose on duodenal calcium-binding protein and calcium absorption, J. Noir. 109: 508–512.Google Scholar
  234. Paul, T., and Flatz, G., 1983, Temporary depression of lactase activity by thyroxine in suckling rats, Enzyme 30: 54–58.PubMedGoogle Scholar
  235. Pautz, W., and J. Vogel, 1895, Über die Einwirkung der Magen-und Darmschleimhaut auf einige Biosen und auf Raffinose, Z. Biol. 32: 304–307.Google Scholar
  236. Pena, A. S., Truelove, S. C., and Whitehead, R., 1973, Morphology and disaccharidase levels of jejunal biopsy specimens from healthy British subjects, Digestion 8: 317–323.PubMedGoogle Scholar
  237. Pena-Yanez, A., Pena Angulo, J. F., and Rico Irles, F., 1971a, Malabsorcion de lactosa en arabes, Rev. Esp. Enferra. Apar. Dig. 34: 13–24.Google Scholar
  238. Pena-Yanez, A., Pena Angulo, J. F., and Juarez Fernandez, C., 1971b, Malabsorcion de la lactosa en estudiantes espanoles, I. Tolerancia intestinal al la sobrecarga oral de lactosa, Rev. Esp. Enferm. Apar. Dig. 35: 925–938.PubMedGoogle Scholar
  239. Perman, J. A., Modler, S., and Olson, A. C., 1981, Role of pH in production of hydrogen from carbohydrates by colonic bacterial flora, J. Clin. Invest. 67: 643–650.PubMedGoogle Scholar
  240. Perman, J. A., Modler, S., Engel, R. R., and Heldt, G., 1985, Effect of ventilation on breath hydrogen measurements, J. Lab. Clin. Med. 105: 436–439.PubMedGoogle Scholar
  241. Piazza, A., Menozzi, P., and Cavalli-Sforza, L. L., 1980. The HLA-A,B gene frequencies in the world: Migration or selection?, Hum. Immunol. 4: 297–304.Google Scholar
  242. Pieters, J. J. L., and Van Rens, R., 1973, Lactose malabsorption and milk tolerance in Kenyan school age children, Trop. Geogr. Med. 25: 365–371.PubMedGoogle Scholar
  243. Plimmer, R. A., 1906, On the presence of lactase in the intestine of animals and on the adaptation of the intestine to lactose, J. Physiol. 35: 20–27.PubMedGoogle Scholar
  244. Porro, G. B., Petrillo, M., Parente, F., Sangaletti, O., and Della Vedova, G., 1981, Recurrent abdominal pain and lactose intolerance, Br. Med. J. 283: 501.Google Scholar
  245. Rahimi, A. G., Delbrück, H., Haeckel, H. W., Goedde, H. W., and Flatz, G., 1976, Persistence of high intestinal lactase activity (lactose tolerance) in Afghanistan, Hum. Genet. 34: 57–62.PubMedGoogle Scholar
  246. Ransome-Kuti, O., Kretchmer, N., Johnson, J. D., and Gribble, J. T., 1972, Family studies of lactose intolerance in Nigerian ethnic groups, Pediatr. Res. 6: 359.Google Scholar
  247. Ransome-Kuti, O., Kretchmer, N., Johnson, J. D., and Gribble, J. T., 1975, A genetic study of lactose digestion in Nigerian families, Gastroenterology 68: 431–436.PubMedGoogle Scholar
  248. Reddy, V., and Pershad J., 1972, Lactase deficiency in Indians, Am. J. Clin. Nutr. 25: 114–119.PubMedGoogle Scholar
  249. Renner, E., 1982. Milch und Milchprodukte in der Ernährung des Menschen, Volkswirtschaftlicher Verlag, Munich.Google Scholar
  250. Rinaldi, E., Albini, L., Costagliola, C., Derosa, G., Auricchio, G., Devizia, B., and Auricchio, S., 1984, High frequency of lactose absorbers among adults with idiopathic senile and presenile cataract in a population with a high prevalence of primary adult lactose malabsorption, Lancet 1: 355–357.PubMedGoogle Scholar
  251. Röhmann, F., and Lappe, J., 1895, Über die Lactase des Dünndarms, Ber. Dtsch. Chem. Ges. 28: 2506–2507.Google Scholar
  252. Röhmann, F., and Nagano, J., 1903, Ueber die Resorption und die fermentative Spaltung der Disaccharide im Dünndarm des ausgewachsenen Hundes, Arch. Ges. Physiol. 95: 533–605.Google Scholar
  253. Rosado, J. L., and Solomons, N. W., 1983, Storage of hydrogen breath test samples in plastic syringes, Clin. Chem. 29: 583–584.PubMedGoogle Scholar
  254. Rosenkranz, W., Hadorn, B., Müller, W., Heinz-Erian, P., Hensen, C., and Flatz, G., 1982, Distribution of adult lactase phenotypes in the population of Austria, Hum. Genet. 62: 158–161.PubMedGoogle Scholar
  255. Rosensweig, N. S., and Herman, R. H., Diet and disaccharidases, 1969, Am. J. Clin. Nutr. 22: 99–102.PubMedGoogle Scholar
  256. Rosensweig, N. S., Huang, S. S., and Bayless, T. M., 1967, Transmission of lactose intolerance, Lancet 2: 277.Google Scholar
  257. Rosenthal, A., and Solomons, N. W., 1983, Time-course of cigarette smoke contamination of clinical hydrogen breath-analysis test, Clin. Chem. 29: 1980–1981.PubMedGoogle Scholar
  258. Rotthauwe, H. W., EI-Schallah, M. O., and Flatz, G., 1971a, Lactose intolerance in Arabs, Hum. Genet. 13: 344–346.Google Scholar
  259. Rotthauwe, H. W., Emons, D., Kaeoplung, M., Tantachamroon, T., and Flatz, G., 1971b, Comparative study of intestinal disaccharidases in Thai and European subjects, Klin. Wochenschr. 49: 503–504.PubMedGoogle Scholar
  260. Rotthauwe, H. W., Emons, D., and Flatz, G., 1972a, Die Häufigkeit der Laktose-Intoleranz bei gesunden Erwachsenen in Deutschland, Dtsch. Med. Wochenschr. 97: 376–380.PubMedGoogle Scholar
  261. Rotthauwe, H. W., Flatz, G., Emons, D., and Heisig, A., 19726, Trennung der intestinalen 3-Galactosidasen beim lactose-toleranten Erwachsenen durch Ultrazentrifugation im Dichtegradienten, Klin. Wochenschr. 50: 258–259.Google Scholar
  262. Rotthauwe, H. W., Flatz, G., Emons, D., and Heisig, A., 1972c, Trennung der intestinalen 3-Galactosidasen beim lactose-intoleranten Erwachsenen durch Ultrazentrifugation im Dichtegradienten, Klin. Wochenschr. 50: 260–261.PubMedGoogle Scholar
  263. Rozen, P., and Shafrir, E., 1968, Behaviour of serum free fatty acids and glucose during lactose tolerance tests. Isr. J. Med. Sci. 4: 100–109.PubMedGoogle Scholar
  264. Sadre, M., and Karbasi, K., 1979, Lactose intolerance in Iran, Am. J. Clin. Nutr. 32: 1948–1954.PubMedGoogle Scholar
  265. Sahi, T., 1974a, The inheritance of selective adult-type lactose malabsorption, Scand. J. Gastroenterol. 9 (Suppl. 30): 1–73.Google Scholar
  266. Sahi, T., 1974b, Lactose malabsorption in Finnish-speaking and Swedish-speaking populations in Finland, Scand. J. Gastroenterol. 9: 303–308.PubMedGoogle Scholar
  267. Sahi, T., and Launiala, K., 1978, Manifestation and occurrence of selective adult-type lactose malabsorption in Finnish teenagers, a follow-up study, Dig. Dis. Sci. 23: 699–704.Google Scholar
  268. Sahi, T., Isokoski, J., Jussila, J., and Launiala, K., 1972, Lactose malabsorption in Finnish children of school age, Acta Paediatr. Scand. 61: 11–16.PubMedGoogle Scholar
  269. Sahi, T., Isokoski, M., Jussila, J., Launiala, K., and Pyördlä, K., 1973, Recessive inheritance of adult-type lactose malabsorption, Lancet 2: 823–826.PubMedGoogle Scholar
  270. Sahi, T., Jussila, J., Penttilä, I., Sarna, S., and Isokoski, M., 1977, Serum lipids and proteins in lactose malabsorption, Am. J. Clin. Nutr. 30: 476–481.PubMedGoogle Scholar
  271. Sahi, T., Launiala, K., and Laitinen, H., 1983, Hypolactasia in a fixed cohort of young Finnish adults, a follow-up study, Scand. J. Gastroenterol. 18: 865–870.PubMedGoogle Scholar
  272. Salmon, P. R., Read, A. E., and McCarthy, C. F., 1969, An isotope technique for measuring lactose absorption, Gut 10: 685–689.PubMedGoogle Scholar
  273. Sasaki, Y., Ilo, M., Kameda, H., Ueda, H., Aoyagi, T., Christopher, N. L., Bayless, T. M., and Wagner, H. N., 1970, Measurement of C-lactose absorption in the diagnosis of lactase deficiency, J. Lab. Clin. Med. 76: 824–835.PubMedGoogle Scholar
  274. Savilahti, E., Launiala, K., and Kuitunen, P., 1983, Congenital lactase deficiency, A clinical study of 16 patients, Arch. Dis. Child. 58: 246–252.PubMedGoogle Scholar
  275. Schmidt, A., and Strasburger, J., 1901, Experimentelle und klinische Untersuchungen über Functionsprüfung des Darmes. VI. Ueber die intestinale Gährungsdyspepsie der Erwachsenen (Insufficienz der Stärkeverdauung), Dtsch. Arch. Klin. Med. 69: 570–605.Google Scholar
  276. Segal, I., Gagjee, P. P., and Noormohamed, A. M., 1983, Lactase deficiency in the South African black population, Am. J. Clin. Nutr. 38: 901–905.PubMedGoogle Scholar
  277. Segall, J. J., 1980, Hypothesis. Is lactose a dietary risk factor for ischaemic heart disease?, Int. J. Epidemiol. 9: 271–276.PubMedGoogle Scholar
  278. Semenza, G., 1981, Small-intestinal glycosidases, in: Carbohydrate Metabolism and Its Disorders ( P. J. Randle, D. F. Steiner, and W. J. Whelan, eds.), pp. 425–479, Academic Press, London.Google Scholar
  279. Semenza, G., Leese, H. J., Colombo, V., and Lorenz-Meyer, H., 1975, The small intestinal ß-glycosidase (lactase-glycosyceramidase) ‘complex,’ Mod. Probl. Paediatr. 15: 186–193.Google Scholar
  280. Seniwiratne, B., Thambipillai, S., and Perera, H., 1977, Intestinal lactase deficiency in Ceylon (Sri Lanka), Gastroenterology 72: 1257–1259.Google Scholar
  281. Seva-Pereira, A., Magalhaes, A. F. N., Pereira-Filho, R. A., and Beiguelman, B., 1983, Primary adult lactose malabsorption, a common trait among Southeastern Brazilians, Rev. Bras. Genet. 6: 747–759.Google Scholar
  282. Shatin, R., 1968, Evolution and lactase deficiency, Gastroenterology 54: 992.PubMedGoogle Scholar
  283. Sheehy, T. W., and Anderson, P. R., 1965, Disaccharidase activity in normal and diseased small bowel, Lancet 2: 1–5.Google Scholar
  284. Shibuya, S., Yamashita, F., and Funatsu, T., 1970, Lactose degradation capacity among Japanese, Adv. Med. 72: 323–324.Google Scholar
  285. Simoons, F. J., 1970, Primary adult lactose intolerance and the milking habit: A problem in biological and cultural interrelations, II. A culture historical hypothesis, Am. J. Dig. Dis. 15: 695–710.PubMedGoogle Scholar
  286. Simoons, F. J., 1973a, New light on ethnic differences in adult lactose intolerance, Am. J. Dig. Dis. 18: 595–611.PubMedGoogle Scholar
  287. Simoons, F. J., 1973b, The determinants of milk use in the Old World: Ecological, physiological and cultural, Ecol. Food. Nutr. 2: 83–90.Google Scholar
  288. Simoons, F. J., 1978, The geographic hypothesis and lactose malabsorption: A weighing of the evidence, Am. J. Dig. Dis. 23: 963–980.PubMedGoogle Scholar
  289. Simoons, F. J., 1980, Age of onset of lactose malabsorption, Pediatrics 66: 646–648.PubMedGoogle Scholar
  290. Simoons, F. J., 1981, Geographic patterns of primary adult lactose malabsorption, a further interpretation of the evidence for the Old World, in: Lactose Digestion, Clinical and Nutritional Implications ( D. M. Paige and T. M. Bayless, eds.), pp. 23–48, Johns Hopkins University Press, Baltimore.Google Scholar
  291. Simoons, F. J., 1982, A geographic approach to senile cataracts. Possible links with milk consumption, lactase activity and galactose metabolism, Dig. Dis. Sci. 27: 257–264.PubMedGoogle Scholar
  292. Skovbjerg, H., 1981, Immunoelectrophoretic studies on human small intestinal brush border proteins—The longitudinal distribution of peptidases and disaccharidases, Clin. Chim. Acta 112: 205–212.PubMedGoogle Scholar
  293. Skovbjerg, H., Gudmand-Hoyer, E., and Fenger, H. J., 1980, Immunoelectrophoretic studies on human small intestinal brush border proteins—Amount of lactase protein in adult-type hypolactasia, Gut 21: 360–364.PubMedGoogle Scholar
  294. Skovbjerg, H., Sjöström, H., and Noren, O., 1981, Purification and characterisation of amphiphilic lactase/phlorizin hydrolase from human small intestine, Eur. J. Biochem. 114: 653–661.PubMedGoogle Scholar
  295. Skovbjerg, H., Noren, O., Sjöström, H., Danielsen, E. M., and Enevoldsen, B. S., 1982, Further characterization of intestinal lactase/phlorizin hydrolase, Biochim. Biophys. Acta 107: 89–97.Google Scholar
  296. Snook, C. R., Mahmoud, J. N., and Wen, P. C., 1976, Lactose tolerance in adult Jordanian Arabs, Trop. Geogr. Med. 28: 333–335.PubMedGoogle Scholar
  297. Socha, J., Kziazyk, J., Flatz, G., and Flatz, S. D., 1984, Prevalence of primary adult lactose malabsorption in Poland, Ann. Hum. Biol. 11: 311–316.PubMedGoogle Scholar
  298. Sofaer, J. A., 1983, Population genetics (Hardy—Weinberg equilibrium and factors affecting it), in: Principles and Practice of Medical Genetics, Vol. 1 ( A. E. H. Emery and D. L. Rimoin, eds.), pp. 80–90, Churchill Livingstone, Edinburgh.Google Scholar
  299. Solomons, N. W., Garcia-Ibanez, R., and Viteri, F. E., 1980, Hydrogen (H2) breath test of lactose absorption in adults: The application of physiological doses and whole cow’s milk sources, Am. J. Clin. Nutr. 33: 545–554.PubMedGoogle Scholar
  300. Solomons, N. W., Torun, B., Caballero, B., Flores-Huerta, S., and Orozco, G., 1984, The effect of dietary lactose on the early recovery from protein-energy malnutrition. I. Clinical and anthropological indices, Am. J. Clin. Nutr. 40: 591–600.PubMedGoogle Scholar
  301. Sowers, M. F., and Winterfeldt, E., 1975, Lactose intolerance among Mexican Americans, Am. J. Clin. Nutr. 28: 704–705.PubMedGoogle Scholar
  302. Spanidou, E. P., and Petrakis, N. L., 1972, Lactose intolerance in Greeks, Lancet 2: 872–873.PubMedGoogle Scholar
  303. Stephenson, L. S., and Latham, M. C., 1974, Lactose intolerance and milk consumption: The relation of tolerance to symptoms, Am. J. Clin. Nutr. 28: 86–88.Google Scholar
  304. Sung, J. L., and Shih, P. L., 1972, The jejunal disaccharidase activity and lactose intolerance in Chinese adults, Asian J. Med. 8: 149–151.Google Scholar
  305. Sunshine, P., and Kretchmer, N., 1964, Intestinal disaccharidases: Absence in two species of sea lions, Science 144: 850–851.PubMedGoogle Scholar
  306. Surjono, A., Sebodo, T., Soenarto, J., and Moenginah, P. A., 1973. Lactose intolerance among healthy adults, Paediatr. lndones. 13: 49–54.Google Scholar
  307. Swvminathan, N., Mathan, V. I., Baker, S. J., and Radakrishnan, A. N., 1970, Disaccharidase levels in jejunal biopsy specimens from American and South Indian control subjects and patients with tropical sprue, Clin. Chim. Acta 30: 707–712.Google Scholar
  308. Tadesse, K., and Eastwood, M., 1977, Breath hydrogen test and smoking. Lancet 2: 91.PubMedGoogle Scholar
  309. Tammur, R., Tamm. A., and Villako, K., 1982, Prevalence of lactose malabsorption (LM) in a randomly selected group of Estonians, Abstract No. 1106. 7th Congress, Organisation Mondiale de Gastroenterologie, Stockholm.Google Scholar
  310. Tandon, R. K., Goel, U., Mukherjee, S. N., Pandey, S. C., and Lal, K., 1977, Lactose intolerance during pregnancy in different Indian communities. Indian J. Med. Res. 66: 33–38.PubMedGoogle Scholar
  311. Tandon, R. K., Yoshi, Y. K., Singh, D. S., Narendranathan, M., Balakrishnan, V., and Lal, K., 1981, Lactose intolerance in north and south Indians, Am. J. Clin. Nutr. 34: 943–946.PubMedGoogle Scholar
  312. Torun, B., Solomons, N. W., Caballero, B., Flores-Huerta, S., Orezco, G., and Pineda, O., 1984, The effect of dietary lactose on the early recovery from protein-energy malnutrition. II. Indices of nutrient absorption, Am. J. Clin. Nutr. 40: 601–610.PubMedGoogle Scholar
  313. Troncale, F. J., Keusch, G. T., Miller, L. H., Olson, R. A., and Buchanan, R. D., 1967, Normal absorption in Thai subjects with nonspecific jejunal abnormalities, Br. Med. J. 4: 578–580.PubMedGoogle Scholar
  314. Tsuboi, K. K., Kwong, L. K., D’Harlingue, A. E., Stevenson, D. K., Kerner, J. A., and Sunshine, P., 1985, The nature of the maturational decline of intestinal lactase activity, Biochim. Biophys. Acta 840: 69–78.PubMedGoogle Scholar
  315. Valenkevich, L. N., 1977, Aktivnost laktazy i sindrom neperenosimosti moloka (Lactase activity and the syndrome of milk intolerance), Klin. Med. (Mosk.) 55: 66–70.Google Scholar
  316. Vazquez, G., Munoz Conde, J. J., Guerrero, M. J., Garcia Miguel, M. J., and Martin, L., 1976, Malabsorption of lactose in Spanish Gypsies, 9th Meeting, European Society of Paediatric Gastroenterology, Weimar, East Germany.Google Scholar
  317. Velebit, L., Cochet, B., and Courvoisier, B., 1978, Incidence de l’intolerance au lactose dans l’osteoporose post-menopausique, Schweiz. Med. Wochenschr. 108: 2061–2065.PubMedGoogle Scholar
  318. Voit, F., 1897, Dtsch. Arch. Klin. Med. 1897:523, cited by Röhrmann and Nagano (1903).Google Scholar
  319. Wang, Y., Yan, Y., Xu, J., Du, R., Flatz, S. D., Kühnau, W., and Flatz, G., 1984, Prevalence of primary adult lactose malabsorption in three populations of northern China, Hum. Genet. 67: 103–106.PubMedGoogle Scholar
  320. Welsh, J. D., 1970, Isolated lactase deficiency in humans: Report on 100 patients, Medicine (Batt.) 49: 257–277.Google Scholar
  321. Welsh, J. D., 1978, Diet therapy in adult lactose malabsorption: Present practices, Am. J. Clin. Nutr. 31: 592–596.PubMedGoogle Scholar
  322. Welsh, J. D., and Hall, W. H., 1977, Gastric emptying of lactose and milk in subjects with lactose malabsorption, Am. J. Dig. Dis. 22: 1060–1063.PubMedGoogle Scholar
  323. Welsh, J. D., Rohrer, V., Knudsen, K. B., and Paustian, F. F., 1967, Isolated lactase deficiency, Correlation of laboratory studies and clinical data, Arch. Int. Med. 120: 26 1269.Google Scholar
  324. Woteki, C. E., Weser, E., and Young, E. A., 1976, Lactose malabsorption in Mexican-American children, Am. J. Clin. Nutr. 29: 19–24.PubMedGoogle Scholar
  325. Woteki, C. E., Weser, E., and Young, E. A., 1977, Lactose malabsorption in Mexican-American adults, Am. J. Clin. Nutr. 30: 470–475.PubMedGoogle Scholar
  326. Yeh, K., and Moog, F., 1974, Intestinal lactase activity in the suckling rat: Influence of hypophysectomy and thyroidectomy, Science 183: 77–79.PubMedGoogle Scholar
  327. Yeh, K., and Moog, F., 1977, Influence of the thyroid and adrenal glands on the growth of the intestine of the suckling rat, and on the development of intestinal alkaline phosphatase and disaccharidase activities, J. Exp. Zool. 200: 337–348.PubMedGoogle Scholar
  328. Yoshida, Y., Sasaki, G., Goto, S., Yanagiya, S., and Takashina, K., 1975, Studies on the etiology of milk intolerance in Japanese adults, Gastroenterol. Jpn. 10: 29–34.PubMedGoogle Scholar
  329. Zuccato, E., Andreoletti, M., Bozzani, A., Marcucci, F., Velio, P., Bianchi, P., and Mussini, E., 1983, Respiratory excretion of hydrogen and methane in Italian subjects after ingestion of lactose and milk, Ear. J. Clin. Invest. 13: 261–266.Google Scholar

Copyright information

© Springer Science+Business Media New York 1987

Authors and Affiliations

  1. 1.Department of Human GeneticsMedizinische Hochschule HannoverHannoverFederal Republic of Germany

Personalised recommendations