单纯17q25.3拷贝数重复导致全面性发育迟缓和多发性先天异常一例

目的探讨单纯17q25.3拷贝数重复的临床特征、遗传方式及基因型与表型的关系。方法应用全外显子测序、染色体微阵列、染色体核型分析、荧光原位杂交技术联合对先证者及其家系成员进行分析。结果先证者为一例4岁的多发性先天异常男性患儿,表现为全面性发育迟缓、矮小、智力障碍、脑发育不良、小头、特殊面容、肌张力低下、注意力缺陷多动障碍、共济失调、骨骼和心血管异常等。全外显子测序和染色体微阵列分析鉴定其在染色体17q25.3→qter发生5.7 Mb拷贝数重复,可能为患儿致病的原因。荧光原位杂交证实先证者该拷贝数重复是遗传自携带该片段平衡易位的母亲,其外祖母和舅舅也为该片段平衡易位携带者,而小姨未见异常。结论本研究结果丰富了单纯17q25.3拷贝数重复的临床表型谱,为遗传咨询提供了依据,并初步提示了P4HB、ACTG1、BAIAP2及TBCD基因为17q25.3拷贝数重复候选基因。

Identification of a 17q25.3 duplication in a Chinese patient with global developmental delay and multiple congenital anomalies

Objective To delineate the clinical features,inheritance pattern,and genotype-phenotype correlation of a Chinese patient with a 17q25.3 duplication.Methods Whole exome sequencing(WES),chromosomal microarray analysis(CMA),chromosomal karyotyping and fluorescence in situ hybridization(FISH)were employed for the analysis of the proband and his family members.Results A 5.7 Mb duplication at 17q25.3→qter was identified by WES and CMA in the 4-year-old boy with multiple congenital anomalies,which was classified as a clinically pathogenic variant.This duplication was confirmed by FISH,and was inherited from his unaffected mother who carried a balanced translocation.Further study revealed that his grandmother also carried the balanced translocation but had gestated three healthy children and had no abortion history.His uncle also carried the balanced translocation,while his aunt was normal.Conclusion Above results have enriched the clinical phenotypes of 17q25.3 duplication.Genetic counseling was provided for the family.P4HB,ACTG1,BAIAP2 and TBCD genes may underlie the clinical features for the 17q25.3 duplication.