Department of Pediatrics, Tokyo Women's Medical University, Tokyo, Japan.
Am J Med Genet A. 2013 Jul;161A(7):1779-85. doi: 10.1002/ajmg.a.35975. Epub 2013 May 23.
Subtelomeric imbalances are a frequent cause of cytogenetic abnormalities in patients with unexplained intellectual disability. Functional disomy of Xq28 involving the methyl-CpG-binding protein 2 gene (MECP2) has been observed mostly in subtelomeric duplications. We identified three patients with functional disomy of Xq28. A female patient showed an unbalanced translocation between 12q24.33 and Xq28. Two male patients showed an unbalanced translocation between Xq27.1- Yq11.22 and a recombinant X-chromosome containing duplicated material from Xq27.1 on Xp telomere, respectively. All three patients exhibited severe developmental delay, hypotonia, seizures, and distinctive facial features, including flat nasal bridge and hypertelorism. Additionally, brain magnetic resonance imaging (MRI) showed characteristic findings in each patient, including frontal dominant brain atrophy and hypoplasia of the corpus callosum, which are common findings in patients with functional disomies of Xq28 and interstitial duplications of Xq28, including MECP2. Brain MRI revealed a cystic lesion in the periventricular white matter in a patient, similar to our previous experience in patients with MECP2 duplication syndrome. Thus, white matter abnormalities may frequently be seen in cases of patients with additional MECP2 copies. © 2013 Wiley Periodicals, Inc.
端粒上的不平衡是导致不明原因智力障碍患者出现细胞遗传学异常的常见原因。Xq28 上的甲基化-CpG 结合蛋白 2 基因（MECP2）的功能单亲二倍体主要见于端粒上的重复。我们鉴定了 3 例 Xq28 上的功能单亲二倍体患者。1 例女性患者表现为 12q24.33 与 Xq28 之间的不平衡易位。2 例男性患者分别表现为 Xq27.1-Yq11.22 之间的不平衡易位和包含 Xq27.1 端粒上重复物质的重组 X 染色体。这 3 例患者均表现为严重的发育迟缓、肌张力低下、癫痫发作和独特的面部特征，包括扁平的鼻梁和宽眼距。此外，脑部磁共振成像（MRI）显示了每位患者的特征性表现，包括额部主导的脑萎缩和胼胝体发育不全，这些表现常见于 Xq28 上的功能单亲二倍体和 Xq28 上的间质性重复，包括 MECP2。脑部 MRI 显示 1 例患者脑室周围白质中有囊性病变，与我们以前在 MECP2 重复综合征患者中的经验相似。因此，在具有额外 MECP2 拷贝的患者中，可能经常会出现白质异常。©2013 Wiley Periodicals, Inc.
