Summary
In this paper observations are summarized and speculations discussed, and it is suggested that some loci on the distal short arm of the X chromosome (Xp) are not randomly inactivated in the female, because they are within the proximal part of the pairing segment between Xp and Yp. This peculiarity of gene expression may be a remnant of the evolutionary history of the sex chromosomes, the pairing segment of which may involve at least 27% of Xp and 95% of Yp. Crossing over seems to occur mostly in the terminal third of the X/Y pairing segment. However, crossing-over inhibition control may lapse, or may be on the X and Y (e.g. Xg, H-Y, STS, and perhaps others) might cross over with a variable frequency which is proportional to their distances from the telomeres of the short arms. It is postulated that the DNA of the pairing segment is composed in a way which may also permit unequal crossing over to occur between the X and the Y, thereby giving rise to exceptions to X-or Y-linked inheritance. The peculiarities of behaviour and the position of other loci on the sex chromosomes are also discussed briefly.
Similar content being viewed by others
References
Armstrong CN, Gray JE, Race RR, Thompson RB (1957) A case of true hermaphroditism. A further report. Br Med J II:605–606
Baltimore D (1981) Gene conversion: some implications for immunoglobulin genes. Cell 24:592–594
Bowen ST (1965) The genetics of Artemia salina V. Crossing over between the X and Y chromosomes. Genetics 52:695–710
Boyd E, Ferguson-Smith MA, Ferguson-Smith ME, Jamieson ME, Russell JE, Aitken DA, Sanger R, Tippett P (1981) A case of X:Y translocation which maps the Xg locus to Xp24→pter (abstract). J Med Genet 18:224
Chapelle A de la (1982) Gene map of the X chromosome. In: Crosignani PG, Rubin E (eds) Genetic control of gamete production and function. Serono Clinical Colloqvia on Reproduction 3, Academic Press (to be published)
Davies KE, Young BD, Elles RG, Hill ME, Williamson, R (1981) Cloning of a representative genomic library of the human X-chromosome after sorting by flow cytometry. Nature 293:374–376
Egel R (1981) Intergenic conversion and reiterated genes. Nature 290: 191–192
Evans HJ, Buckton KE, Spowart G, Carothers AD (1979) Heteromorphic X chromosomes in 46,XX males: evidence for the involvement of X-Y interchange. Hum Genet 49:11–31
Fellous M, Pearson PL, Linden AGJM van der, Meera Khan P, Hagemeijer A (1975) Mapping the Xga red blood cell antigen in human-Chinese hamster cell hybrids: the Xg locus is possibly located on the short arm of the X chromosome. Cytogenet Cell Genet 14:293–295
Ferguson-Smith MA (1966) X-Y chromosomal interchange in the aetiology of true hermaphroditism and of XX Klinefelter's syndrome. Lancet II:475–476
Frøland A (1964) Quoted in Sanger et al. (1964)
Gartler SM, Andina RJ (1976) Mammalian X-chromosome inactivation. Adv Hum Genet 7:99–140
Holm PB, Rasmussen SW (1977) Human meiosis. I. The human pachytene karyotype analyzed by three dimensional reconstruction of the synaptonemal complex. Carlsberg Res Commun 42:283–324
Jacobs PA, Hunt PA, Mayer M, Bart RD (1981) Duchenne muscular dystrophy (DMD) in a female with an X/autosome translocation: further evidence that the DMD locus is at Xp21. Am J Hum Genet 33:513–518
Judd BH (1976) Genetic units of Drosophila—complex loci. In: Ashburner M, Novitski E (eds) The genetics and biology of Drosophila 1B. Academic Press, New York, p 785
Lewin B (1980) Gene expression 2: Eucaryotic chromosomes. Wiley Interscience, Chichester New York Brisbane Toronto Singapore, pp 865–906
Lyon MF (1974) Evolution of X-chromosome inactivation in mammals. Nature 250:651–653
McKusick VA (1981) The human gene map as at 15.5.81. Personal communication
Mohandas T, Shapiro LJ, Sparkes RS, Sparkes MC (1979) Regional assignment of the steroid sulfatase-X-linked ichthyosis locus: implications for a noninactivated region of the short arm of human X chromosome. Proc Natl Acad Sci USA 76:5779–5783
Moses MJ, Counce SJ, Paulson DF (1975) Synaptonemal complex complement of man in spreads of spermatocytes, with details of the sex chromosome pair. Science 187:363–365
Müller CR, Migl B, Traupe H, Ropers HH (1980) X-linked steroid sulfatase: evidence for different gene-dosage in males and females. Hum Genet 54:197–204
Ohno S (1967) Sex chromosomes and sex-linked genes. Springer Verlag, Berlin Heidelberg New York
Paris Conference (1971) Standardization in human cytogenetics. Birth Defects: Original Article Series VIII/7:42
Pierella P, Craig I, Bobrow M, Chapelle A de la (1981) Steroid sulfatase levels in XX males, including observations on two affected cousins. Hum Genet 59:81–87
Polani PE (1962) Sex-chromosome anomalies in man. In: Hamerton JL (ed) Chromosomes in medicine. Little Club Clinics in Developmental Medicine 5, National Spastics Society and William Heinemann Medical Books, London, pp 73–139
Polani PE (1981a), Abnormal sex development in man. I. Anomalies of sex-determining mechanisms. In: Austin CR, Edwards RG (eds) Mechanisms of sex differentiation in animals and man. Academic Press, London New York Toronto Sydney San Francisco, pp 481–483
Polani PE (1981b), Abnormal sex development in man. I. Anomalies of sex-determining mechanisms. In: Austin CR, Edwards RG (eds) Mechanisms of sex differentiation in animals and man. Academic Press, London New York Toronto Sydney San Francisco, p 477
Ropers HH, Migl B, Zimmer J, Müller CR (1981) Steroid sulfatase activity in cultured fibroblasts of XX males. Cytogenet Cell Genet 30:168–173
Sanger R, Race RR, Tippett P, Gavin J, Hardisty RM, Dubowitz V (1964) Unexplained inheritance of the Xg groups in two families. Lancet I:955–956
Searle AG (1981) Personal communication
Solari AJ (1980) Synaptonemal complexes and associated structures in microspread human spermatocytes. Chromosoma 81:315–337
Solari AJ, Tres LL (1970) The three-dimensional reconstruction of the XY chromosomal pair in human spermatocytes. J Cell Biol 45: 43–53
Therkelsen AJ (1964) Sterile male with the chromosomal constitution 46,XX. Cytogenetics 3:207–218
Therman E, Sarto GE, Palmer CG, Kallio H, Denniston C (1970) Position of the human X inactivation center on Xq. Hum Genet 50: 59–64
Tiepolo L, Zuffardi O, Fraccaro M, di Natale D, Gargantini L, Müller CR, Ropers HH (1980) Assignment by deletion mapping of the steroid sulfatase X-linked ichthyosis locus to Xp223. Hum Genet 54:205–206
Vogel F, Rathenberg R (1975) Spontaneous mutation in man. Adv Hum Genet 5:223–318
Winter RM, Pembrey ME (1982) Hypothesis: does unequal crossing over contribute to the mutation rate in Duchenne muscular dystrophy? Am J Med Genet (to be published)
Wolf U (1981) Genetic aspects of H-Y antigen. Hum Genet 58:25–28
Wolf U, Fraccaro M, Mayerová A, Hecht T, Maraschio P, Hameister H (1980) A gene controlling H-Y antigen on the X chromosome. Tentative assignment by deletion mapping to Xp223. Hum Genet 54:149–154
Yamamoto T-O (1961) Progenies of sex-reversal females mated with sex-reversal males in the medaka, Oryzias latipes. J Exp Zool 146: 163–179
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Polani, P.E. Pairing of X and Y chromosomes, non-inactivation of X-linked genes, and the maleness factor. Hum Genet 60, 207–211 (1982). https://doi.org/10.1007/BF00303003
Received:
Issue Date:
DOI: https://doi.org/10.1007/BF00303003