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The vanishing twin: An explanation for discordance between chorionic villus karyotype and fetal phenotype
Author(s) -
Reddy K. S.,
Petersen M. B.,
Antonarakis S. E.,
Blakemore K. J.
Publication year - 1991
Publication title -
prenatal diagnosis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.956
H-Index - 97
eISSN - 1097-0223
pISSN - 0197-3851
DOI - 10.1002/pd.1970110903
Subject(s) - chorionic villi , karyotype , fetus , chorionic villus sampling , biology , placenta , in utero , dizygotic twin , andrology , twin pregnancy , gestation , prenatal diagnosis , genetics , chromosome , pregnancy , medicine , twin study , gene , heritability
One ‘erroneous’ diagnosis occurred in 200 first‐trimester chorionic villus samples (CVS) analysed. In direct preparations following 24 h incubation as well as in long‐term cultures, a 46.XX karyotype was observed in the villi (28 and 25 cells, respectively). At 20 weeks of gestation, labour was induced because of fetal death in utero . An autopsy performed on the fetus revealed a male phenotype. Placenta and fetal tissues were not submitted for cytogenetic studies. The discordant CVS karyotype (46,XX), in view of the male fetal phenotype, prompted further cytogenetic and molecular studies. Chromosome marker studies on the parents' blood and chorionic villi confirmed both maternal and paternal inheritance of chromosomes in the CVS. DNA studies on formalin‐fixed skin using a Y‐specific probe, DYZ1, confirmed the presence of a Y chromosome in the fetus. The most likely cause of the discrepant CVS karyotype is the presence of an undetected degenerating dizygotic twin.