摘要目的:探讨1例5q14.3微缺失综合征患儿的临床表型和遗传学病因。方法:应用全外显子组测序技术(whole exome sequencing，WES)及低深度全基因组测序技术(low-coverage massively parallel copy number variation sequencing，CNV-seq)对患儿进行可能致病变异及染色体拷贝数变异(copy number variations，CNVs)分析，对检测到的微小基因组拷贝数异常区域通过实时荧光定量PCR进行验证。结果:患儿主要临床表现包括全面性发育迟缓、癫痫、特殊面容、肌张力低下。WES检测提示患儿chr5：86 564 268-88 119 605区可能存在杂合缺失。CNV-seq检测提示患儿5q14.3区存在大小为4.76 Mb的杂合缺失。对缺失区域内的 MEF2C基因和 RASA1基因应用实时荧光定量PCR进行验证，结果显示 MEF2C基因和 RASA1基因杂合缺失，与测序结果相符。 结论:通过临床及基因测序分析，患儿被诊断为5q14.3微缺失综合征。该患儿的 MEF2C基因单倍体不足可能是导致5q14.3微缺失综合征神经精神发育障碍相关临床表型的主要原因。

abstractsObjective:To explore the clinical features and genetic characteristics of a child with 5q14.3 microdeletion syndrome.Methods:Whole exome sequencing(WES)and low-coverage massively parallel copy number variation sequencing(CNV-seq)were used to determine the potentially pathogenic variants as well as the copy number variations(CNVs). Candidate CNVs were verified by real-time fluorescence quantitative PCR.Results:The patient presented with psychomotor retardation, epilepsy, peculiar face and hypotonia. The results of WES suggested that the patient carried a heterozygous deletion for chr5: 86 564 268-88 119 605. CNV-seq indicated that he has carried a heterozygous deletion of 4.76 Mb heterozygous deletion on chromosome 5q14.3. The MEF2C gene and RASA1 genein the deletion area were verified by real-time fluorescence quantitative PCR. The results showed that the MEF2C gene and RASA1 gene were heterozygous deletion, which was consistent with the sequencing results. Conclusion:The child was diagnosed with 5q14.3 microdeletion syndrome. Haploinsufficiency of the MEF2C gene may underlie the manifestations of 5q14.3 microdeletion syndrome.