Cryptic duplication of the distal segment of 22q due to a translocation (21;22): three case reports and a review of the literature

European Journal of Medical Genetics
I FeenstraC M A Van Ravenswaaij

Abstract

Duplications of the proximal segment of chromosome 22q are not uncommon, like Cat-eye syndrome and duplications due to familial (11;22) translocations. However, duplications of the distal long arm of chromosome 22 (22qter) seem to be exceedingly rare. So far, duplications of 22q12 or 22q13 to 22qter have been described in 21 patients, of whom 13 had a pure duplication 22qter. Here we report on three new cases with a pure duplication of the distal part of 22q. The first patient carries a duplication of terminal 22q due to a de novo unbalanced translocation, 46,XX,der(21)t(21;22) (p13;q13.2), detected by NOR-staining, while the other patients have a familial cryptic duplication of terminal 22q due to an unbalanced translocation, 46,XY,der(21)t(21;22)(p10;q13.3). The last two patients were initially thought to have a polymorphic variant of 21p, but additional subtelomeric screening using FISH showed the extra material was derived from chromosome 22. Terminal duplications of 22qter may be more common than generally assumed, but due to its small size, especially when located on an acrocentric chromosome and/or possibly relatively mild phenotype remain undetected thus far.

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Citations

Nov 1, 1994·Nature Genetics·P J Willems
Aug 12, 2008·European Journal of Medical Genetics·Brigitte H W FaasConny M A van Ravenswaaij-Arts
May 19, 2009·American Journal of Medical Genetics. Part a·Keiko ShimojimaToshiyuki Yamamoto
Oct 20, 2009·American Journal of Medical Genetics. Part a·Nicola Brunetti-PierriRubina A Heptulla
Oct 30, 2008·American Journal of Medical Genetics. Part a·Marzena GajeckaLisa G Shaffer
Jun 12, 2008·American Journal of Medical Genetics. Part a·Tiziano PramparoRenzo Guerrini
Nov 22, 2011·The Journal of Maternal-fetal & Neonatal Medicine : the Official Journal of the European Association of Perinatal Medicine, the Federation of Asia and Oceania Perinatal Societies, the International Society of Perinatal Obstetricians·Lyn S ChittyLisa Levett
Nov 3, 2007·American Journal of Medical Genetics. Part a·Nobuhiko OkamotoShigeo Uchino
Oct 29, 2008·Clinical Dysmorphology·Aleksandra Jezela-StanekMałgorzata Krajewska-Walasek
Dec 1, 2007·Clinical Dysmorphology·Christine M ArmourJudith E Allanson

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