The absence of the uniparental inheritance of X-chromosomes in spontaneously aborted fetuses with karyotype 46.XX

The problem of the presence of imprinted regions on the X-chromosome and the possible influence of the imprinted expression of X-linked genes on the embryonic development in man remains largely unsolved. A comparison of the uniparental inheritance of chromosomes or of their regions having different phenotypic manifestations provides an instrument with which to study the phenomenon of genomic imprinting at the chromosomal level. Assuming that the imprinted inactivation of X-chromosomes is functionally significant for embryonic development, we have studied several polymorphic micro- and minisatellite loci of X-chromosomes in 52 fetuses with karyotype 46.XX, which were spontaneously aborted during the first trimester of pregnancy. The purpose was to determine the contribution of uniparental disomy for the X-chromosome in any disturbances of the embryonic development. We found that inheritance of X-chromosomes was biparental in the studied embryos, suggesting the absence of any significant contribution of the parental origin of the X-chromosome to embryonic mortality occurring between 4 and 12 weeks of development.