Mosaic ring chromosome 21, monosomy 21, and isodicentric ring chromosome 21: Prenatal diagnosis, molecular cytogenetic characterization, and association with 2-Mb deletion of 21q21.1–q21.2 and 5-Mb deletion of 21q22.3

Abstract

An extra interstitial 21q deletion can be associated with mosaic r(21) in addition to a terminal 21q deletion. aCGH is useful in determining the breakpoints and associated subtle structural abnormalities in cases of prenatally detected ring chromosome in order to facilitate genetic counseling.