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Chimerism involving a RB1 pathogenic variant in monochorionic dizygotic twins with twin–twin transfusion syndrome
Author(s) -
Armitage Anna M.,
Kundra Monica A.,
Ghiam Neda,
Atwal Paldeep S.,
Morel Dayna,
Hruska Kathleen S.,
Torene Rebecca,
Harbour J. William,
Forghani Irman
Publication year - 2021
Publication title -
american journal of medical genetics part a
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.064
H-Index - 112
eISSN - 1552-4833
pISSN - 1552-4825
DOI - 10.1002/ajmg.a.61913
Subject(s) - twin twin transfusion syndrome , genotyping , twin study , dizygotic twins , dizygotic twin , allele , medicine , immunology , biology , genetics , gene , obstetrics , genotype , fetus , pregnancy , heritability
We report the first case of blood chimerism involving a pathogenic RB1 variant in naturally conceived monochorionic‐dizygotic twins (MC/DZ) with the twin–twin‐transfusion syndrome (TTTS), presumably caused by the exchange of stem‐cells. Twin A developed bilateral retinoblastoma at 7 months of age. Initial genetic testing identified a de novo RB1 pathogenic variant, with a 20% allelic ratio in both twins' blood. Subsequent genotyping of blood and skin confirmed dizygosity, with the affected twin harboring the RB1 pathogenic variant in skin and blood, and the unaffected twin carrying the variant only in blood.