摘要目的 探讨1例智力低下、生长发育迟缓并伴有多系统紊乱的患儿的遗传学原因,分析患儿基因组拷贝数变异(copy number variations,CNVs)及其所含基因与临床表型的关系.方法 用常规G显带技术分析患儿及其父母外周血染色体核型,之后应用单核苷酸多态微阵列技术(single nucleotide polymorphisms array,SNP-array)对患儿进行全基因组扫描分析,进而采用荧光原位杂交技术(fluorescence in situ hybridization,FISH)进行实验验证.结果 患儿及其父母的外周血常规染色体核型分析未见异常.SNP-array分析结果显示7q11.23区域杂合性缺失,长度为1673 kb,其缺失与Williams-Beuren综合征相关.FISH实验结果验证了此微缺失的存在,并通过检测其父母FISH结果,证实为一种新发的缺失.结论 用SNP-array结合FISH技术确诊了1例Williams-Beuren综合征,患儿的临床表型与其染色体微缺失的片段7q11.23相关.与传统的细胞遗传学分析方法相比,SNP-array在临床检测不明原因智力低下、发育迟缓患者中具有显著优势.

abstractsObjective To explore the genetic cause for a child with mental retardation,developmental delay and multi-systemic developmental disorders by analyzing the copy number variations (CNVs) and correlating the genotype with the phenotype.Methods Routine G-banding was performed to analyze the karyotype of the patient and her parents.In addition,single nucleotide polymorphisms array (SNP-array) was used to determine the CNVs,which was confirmed by fluorescence in situ hybridization (FISH).Results No karyotypic abnormality was detected upon chromosome analysis.However,SNP-array has identified a de novo hemizygous deletion of 1673 kb on chromosome region 7q11.23,which has been associated with Williams-Beuren syndrome.The microdeletion was confirmed by FISH testing.Conclusion A child with Williams-Beuren syndrome has been diagnosed by SNP-array and FISH.The de novo 7q11.23 mierodeletion probably underlies the clinical manifestation of the patient.Compared with routine karyotype analysis,SNP-array is more useful for diagnosing children with multiple congenital anomalies with unclear etiology.