[Effect of maternal genetic heterozygosity]. / Effekt geterozigotnosti materi po nekotorym genam

The obstetrics histories of all the pregnances were studied, including the deliveries and abortions, the perinatal mortality of fetuses and the frequency of congenital malformations among newborns in 239 repeatedly pregnant women heterozygous for the gene of phenylketonuria (PKU), 40 women with the latent form of diabetes mellitus (LDM) and 96 women heterozygous for Dushenne's myopathy (MD). It was established that the frequency of women suffering from spontaneous abortions (SA) was increased as well as the SA frequency among all the pregnancies with natural results in heterozygotes for the PKU gene; it was also established that the frequency of stillborns and of the early mortality of newborns was considerably higher among women with LDM. In both these groups the frequency of congenital malformations among the newborns was also relatively high. In women heterozygous for the PKU gene the pathogenic effect was realized only during the first three months of pregnancy, while in women with LDM it was realized through all the period of pregnancy. The heterozygosity of women for MD proved not to be pathogenic for the progeny. Possible mechanisms realizing the effect of heterozygosity of women for the abovementioned recessive genes during pregnancy are discussed.