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‘Identical’ twins with discordant karyotypes
Author(s) -
Nieuwint Aggie,
Van ZalenSprock Rieteke,
Hummel Pieter,
Pals Gerard,
Van Vugt John,
Van Der Harten Hans,
Heins Yvonne,
Madan Kamlesh
Publication year - 1999
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/(sici)1097-0223(199901)19:1<72::aid-pd465>3.0.co;2-v
Subject(s) - karyotype , obstetrics , fetus , twin pregnancy , chorionic villus sampling , pregnancy , monozygotic twin , prenatal diagnosis , trisomy , umbilical cord , amniotic fluid , biology , gynecology , medicine , chromosome , genetics , gene
Abstract A chromosomal abnormality in one of the fetuses of a monozygotic twin pregnancy is a rare phenomenon. In the prenatal unit of our cytogenetics laboratory we have recently come across two such heterokaryotypic twin pregnancies. In both cases ultrasound abnormalities were detected in one fetus of each twin pair. Chromosomal analysis showed that one twin pregnancy was discordant for trisomy 21 and the other for 45,X. Ultrasonographic examination suggested a monochorionic twin pregnancy in each case and DNA studies confirmed that both sets of twins were monozygotic. Both pregnancies were terminated. Biopsies taken from different sites of the placentas showed chromosomal mosaicism in both cases. There was no clear correlation between the karyotype found close to the site of the umbilical cord insertion in the placenta and the karyotype of the fetus. Sampling of amniotic fluid from both sacs is recommended in diamniotic twin pregnancies if one (or both) of the fetuses has ultrasound abnormalities, even if the twins are apparently monochorionic. Copyright © 1999 John Wiley & Sons, Ltd.