Vergleichende Genfrequenzuntersuchungen für den Galaktokinasedefekt in der Steiermark und in Franken

Abstract

Blood samples from 1885 individuals of two collectives (Styria in Austria: 997; Franconia in Bavaria, Federal Republic of Germany: 888) were assayed for galactokinase activity. The enzyme activity was estimated by the method of Beutler et al. [1] with the aid of galactose-1-C¹⁴. The radioactivity was measured on a Tricarbscintillation counter (Packard). The blood samples were obtained from blood donors in Austria and from healthy children of the pediatric clinic of the University of Erlangen. Eight individuals in Styria had galactokinase activity about one half the normal value; they were considered to be heterozygotes for the galactokinase deficiency. The calculated gene frequency indicates that approximately 1 in 62 500 individuals can be expected to have a galactokinase deficiency. In Bavaria we found 5 individuals with heterozygous values. The gene frequency for this area was estimated at 1 in 84 000. To date we have found only one publication, by Mayes, about gene frequency for galactokinase deficiency. This author found a gene frequency of 1 in 46 000. It is very important to detect the heterozygote carriers of this inborn error of metabolism, since cataract formation in these individuals might be prevented by restriction of galactose intake in these subjects. This disorder is much more common in the population than the case reports would indicate. The possible causes of the different gene frequencies are discussed.

Zusammenfassung

1885 Probanden aus 2 Kollektiven (Steiermark: 997, Franken: 888) wurden bezüglich ihrer Galaktokinaseaktivität mit der Methode von Beutler et al. [1] (radioktiv markierte Galaktose) untersucht. Aus der Anzahl der Heterozygoten in der Steiermark (n=8) errechnete sich eine Homozygotenfrequenz von 1:62 500; aus der Zahl der Heterozygoten in Franken (n=5) ergab sich eine Homozygotenfrequenz von 1:127 000. Faßt man die Ergebnisse aus beiden Ländern zusammen, so liegt die errechnete Homozygotenfrequenz bei 1:84 000. Die möglichen Gründe für die unterschiedliche Frequenz werden dargelegt und mit den wenigen Befunden in der Literatur verglichen.