SKEWED X-CHROMOSOME INACTIVATION IN HUMAN MISCARRIAGES
E.N. Tolmacheva,1,3,* S.A. Vasilyev,1,2 E.A. Sazhenova,1 D.I. Zhigalina,2
E.I. Grigorovich,2 T.V. Nikitina,1 A.A. Melnikov,1 E.S. Zhabina,3 T.V. Ivanova,3
I.D. Evtushenko,3 I.N. Lebedev 1-3
1 Institute of Medical Genetics, Tomsk, 634050,
2 National Researche Tomsk State University, 634050,
and 3 Siberian State Medical University, Tomsk, 634050;
* e-mail: kate.tolmacheva@medgenetics.ru
Sex ratio in first trimester of pregnancy is skewed due to preferential elimination of female embryos. It could be resulted from aberrant X-chromosome inactivation. X-chromosome
inactivation was analyzed in extra-embryonic tissues of miscarriages and induced abortions with 46, XX karyotype. In chorion cytotrophoblast of both miscarriages and induced
abortions observed either random or skewed X-chromosome inactivation. In extraembryonic mesoderm of the control group, random inactivation was observed, whereas 15 % of
miscarriages had skewed X-chromosome inactivation. The highest frequency of skewed inactivation of one of the parental homologues was observed in the groups of blighted ovum
pregnancy and embryos from women with recurrent pregnancy loss. It was suggested that in these cases compartmentalization of cells in the blastocyst probably leads to
predominance of cell with mutant active X-chromosome among the cells of inner cell mass carrying the aberrations that are incompatible with normal embryonic development.
Key words:
miscarriage, blighted ovum pregnancy, X-chromosome inactivation, recurrent pregnancy loss
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