一例9q34.3微缺失综合征患儿的临床及遗传学分析

Clinical and genetic analysis of a boy with 9q34. 3 microdeletion syndrome

目的明确1例智力低下、发育迟缓的患儿染色体拷贝数变异的性质及来源，分析其与表型的相关性。方法采用常规G显带分析患儿及其父母的外周血染色体核型，并用微阵列比较基因组杂交（array comparative genomic hybridization，aCGH）技术进行检测。结果患儿及其父母核型未见异常，aCGH检测结果显示患儿染色体9q34．3区存在405kb的杂合缺失，该区域包含EHMT1基因和部分CACNAlB基因，其父母则未携带染色体微重复／微缺失。结论患儿染色体9q34．3区的杂合缺失为新发突变，可能是患儿患病的原因。EHMTl可能是9q34．3微缺失综合征关键基因之一。

Objective To determine the origin of chromosomal aberration in a boy with mental retardation and multiple congenital malformations. Methods The karotypes of the proband and his parents were analyzed with conventional G-banding. Their genomic DNA was analyzed with array comparative genomic hybridization （aCGH）. Results No karyotypic abnormality was detected in the proband and his parents, aCGH has identified a de novo 405 kb deletion at 9q34.3 in the proband, which encompassed the EHMT1 gene and part of CACNA1B gene. Conclusion The de novo 9q34.3 deletion probably underlies the mental retardation and development delay in the boy. EHMT1 may be one of the key genes responsible for 9q34.3 microdeletion syndrome.