Blennow E, Lagerstedt K, Malmgren H, Sahlén S, Schoumans J, Anderlid Bm
Clinical Genetics Unit, Department of Molecular Medicine and Surgery, Karolinska Institutet, Stockholm, Sweden.
Clin Genet. 2008 Jul;74(1):61-7. doi: 10.1111/j.1399-0004.2008.01008.x. Epub 2008 Apr 28.
Microduplication of 22q11.2 has been reported in fewer than 40 cases, all of them including the DiGeorge critical region (DGCR). We here present the characterization of a new duplication that does not include the DGCR. The duplication was initially found by multiplex ligation-dependent probe amplification analysis of 22q11.2 in a young girl with a concurrent deletion of the DGCR in 70% of her peripheral blood lymphocytes. Her phenotype included many of the features of the velocardiofacial syndrome, with velopharyngeal insufficiency, recurrent infections, learning and concentration problems as well as difficulties in social interactions. However, there were no congenital malformations, and her facial appearance was not typical for the syndrome. Further investigations included array comparative genomic hybridization (CGH) to size map the deletion/duplication and interphase fluorescent in situ hybridization to investigate mosaicism and the structure of the rearrangement. An identical duplication of this part of 22q11.2 has not been reported before, and the duplication itself seems to be associated with very mild or no symptoms. This study contributes to the growing knowledge regarding new deletions and duplications of 22q11.2, most of them mediated by the pre-disposing high number of low-copy repeats in the region.
22q11.2微重复的报告病例不到40例，所有病例均包含迪乔治关键区域（DGCR）。我们在此展示了一例不包含DGCR的新重复病例的特征。该重复最初是通过对一名年轻女孩的22q11.2进行多重连接依赖探针扩增分析发现的，其外周血淋巴细胞中有70%同时存在DGCR缺失。她的表型包括腭咽闭合不全、反复感染、学习和注意力问题以及社交互动困难等许多腭心面综合征的特征。然而，她没有先天性畸形，面部外观也并非该综合征的典型表现。进一步的研究包括采用阵列比较基因组杂交（CGH）来确定缺失/重复的大小，以及采用间期荧光原位杂交来研究嵌合体和重排结构。此前尚未报道过22q11.2这一部分的相同重复，且该重复本身似乎与非常轻微的症状或无症状相关。这项研究有助于增加对22q11.2新缺失和重复的认识，其中大多数是由该区域大量的易位低拷贝重复介导的。
