[Investigation of the frequency of heterozygotes for galactose-1-phosphate-uridyl-transferase-deficiency(galactosemia) in the Vienna area. Comparison with the frequency of homozygotes found by newborn screening (author's transl)].
By routine newborn screening for galactose blood level elevations a great difference in the frequency of Galactosemia by transferase deficiency was observed between Eastern- and Western-Austria. This made enzymatic heterozygousity determinations desirable. At the same time it should be examined whether the frequency of homozygotes found by screening correlates with the frequency derived from the heterozygousity frequency. In a first step the region of Vienna was studied. 377 unselected blood samples were examined following BEUTLER-BALUDA's method. As technical control samples of 9 homozygotes and 12 heterozygotes as found by screening were examined but not included in the frequency study. Arranged following age groups a slight but significant decrease of enzym activity with increasing age could be confirmed (23,89 versus 21,99 U/g Hb). This, increasing the overlapping between normals and heterozygotes of different ages possibly should be kept in mind in individual heterzygousity determinations. The enzymatically determined frequency of heterozygotes was found to be twice as high as the frequency calculated from the frequency of biochemically detected but enzymatically proven homozygotes (1:53 versus 1:99). A comparison of the heterozygousity frequencies found in literature with the results of the most efficient (technically most reliable) screening programs shows that this discrepancy is great and general. Bases on heterozygousity frequencies the frequency of homozygotes found by screening programs seems to be at least 50% too low. Analysis of theoretical possibilities for loss of homozygotes by screening programs makes this explanation highly improbable. It seems more probable that the enzymatically determined heterozygotes frequency is too high by including still undefined allels or allel combinations which result in about half normal activity but not in disturbances resembling classical Galactosemia.
D000367:Age Factors; D001317:Austria; D005693:Galactosemias / Q000175:diagnosis* / Q000235:genetics; D006579:Heterozygote; D006720:Homozygote; D006801:Humans; D007231:Infant, Newborn; D007232:Infant, Newborn, Diseases / Q000175:diagnosis*; D008403:Mass Screening; D013223:Statistics as Topic; D005694:UTP-Hexose-1-Phosphate Uridylyltransferase / Q000097:blood / Q000172:deficiency
D005694:UTP-Hexose-1-Phosphate Uridylyltransferase
Untersuchung über die Häufigkeit von Heterozygoten für Galaktose-1-Phosphat-Uridyl-Transferase-Mangel (Galaktosmie) im Raum von Wien. Vergleich mit der durch Neugeborenen-Screening gefundenen Homozygoten-Häufigkeit