Journal
AMERICAN JOURNAL OF MEDICAL GENETICS PART A
Volume 146A, Issue 16, Pages 2086-2093Publisher
WILEY
DOI: 10.1002/ajmg.a.32431
Keywords
twins; monozygosity; trisomy 21; discordant
Categories
Ask authors/readers for more resources
We report on a monochorionic/diamniotic twin pregnancy discordant for trisomy 21. Amniocentesis (at 135/7 weeks) was performed following ultrasound signs of hydrops and cystic hygroma in twin 1 (T1). Prenatal karyotype showed non-mosaic trisomy 21 in T1 (47,XX,+21[7]), and low-grade mosaic trisomy 21 in twin 2 (T2) (47 XX,+21[2]/46,XX[19]). Post mortem examination of fetal skin, kidneys and lungs confirmed trisomy 21 in T1 (47,XX,+21[548]) and the placenta (47 XX +21[200]). T2 had a normal karyotype (46,XX[648]). Analysis of microsatellite polymorphisms in multiple samples from the placenta, hand, lungs, kidneys and the umbilical cords of both twins confirmed mono-zygosity for all loci tested, and trisomy 21 in T1. Unexpectedly, T1 and T2 inherited different maternal alleles for markers of the most distal 4 Mbp of 21q. At least four successive events are needed to explain the genetic status of both twins and include maternal MI premature chromatids separation or maternal II meiotic nondisjunction and postzygotic events Such as, chromosome rescue, nondisjunction, an/or recombination. (C) 2008 Wiley-Liss, Inc.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available