一例3p26．3-pter缺失及7q31．33-qter重复患儿的临床表型与遗传学分析

Phenotypic and genetic analysis of a boy with 3p26.3-pter deletion and 7q31.33-qter duplication

目的明确1例发育落后合并多发畸形患儿染色体拷贝数变异（copy numbervariants，CNVs）的性质及来源，并分析其与表型的相关性。方法应用常规G显带分析患儿及其父母的外周血染色体核型，应用二代测序（next generation sequencing，NGS）技术对患儿进行检测。结果G显带分析显示患儿的3号染色体存在结构异常，其父亲的染色体核型为46，XY，t（3；7）（p26；q31），其母亲核型未见异常。NGS检测显示患儿染色体3p26．3-pter区存在约2．16Mb的微缺失，7q31．33-qter区存在约34．24Mb的重复。结论患儿3号染色体的结构异常源自其父亲的t（3；7）平衡易位，其核型为46，XY，der（3）t（3；7）（p26．3；q31．33）pat。3p26．3-pter区微缺失和7q31．33-qter区重复是导致患儿异常表型的原因。

Objective To delineate the nature and origin of chromosomal copy number variants （CNVs） in a boy with mental retardation and multiple congenital malformation. Methods The karyotypes of the patient and his parents were analyzed with routine G-banded chromosomal analysis. Genome DNA was analyzed by next generation sequencing （NGS）. Results The patient was found to harbor a structural aberration involving chromosome 3p. The karyotype of his father was 46, XY, t（3;7）（p26;q31）, while his mother was found to be normal. NGS analysis of the patient revealed a 2.16 Mb microdeletion at 3p26.3- pter and a duplication at 7q31.33-qter. Conclusion The structural aberration of 3p carried by the patient has derived from his father whom carried a balanced translocation of t（3;7）, and his karyotype was finally determined as 46, XY, der （3） t （3 ; 7） （p26. 3 ; q31. 33） pat. The abnormal phenotype of the patient can probably be attributed to the presence of 3p26.3-pter microdeletion and 7q31.33-qter duplication.