一例Phelan-McDermid综合征合并21q21微缺失胎儿的产前遗传学诊断

Prenatal diagnosis of a fetus with Phelan-McDermid syndrome and 21q21 microdeletion by multiple genetic techniques

目的应用多种遗传学检测技术对1例产前超声异常胎儿进行遗传学分析,为其遗传咨询及产前诊断提供依据。方法应用染色体核型分析和单核苷酸多态性微阵列(single nucleotide polymorphism array,SNP-array)技术对1例超声异常胎儿行产前诊断,并结合荧光原位杂交技术(fluorescence in situ hybridization,FISH)对检测结果进一步验证。结果胎儿及父母染色体核型分析均未发现异常;SNP-array分析结果提示胎儿染色体22q13.31q13.33区存在5.1 Mb片段杂合性缺失,提示为Phelan-McDermid综合征,同时合并21q21.1q21.2区4.5 Mb片段杂合性缺失;经FISH验证这两个异常片段均为新发,父母不存在平衡易位。结论胎儿染色体22q13.31q13.33和21q21.1q21.2区杂合性缺失可能与胎儿异常表型相关,产前遗传学分析可以为其产前诊断及遗传咨询提供依据。

Objective To carry out prenatal diagnose for a fetus with ultrasonography abnormalities using multiple genetic techniques.Methods Routine G-banding chromosomal analysis and single nucleotide polymorphism array(SNP-array)were applied in conjunction for the prenatal diagnosis of the fetus.The result was confirmed by fluorescence in situ hybridization(FISH).Results SNP-array detected that the fetus has carried a hemizygous 5.1 Mb deletionat 22q13.31q13.33,which is associated with Phelan-McDermid syndrome,and a hemizygous 4.5 Mb deletion at 21q21.1q21.2.FISH analysis of the fetus and its parents suggested that both deletions were de novo in origin.Conclusion The hemizygous deletions on 21q21.1q21.2 and 22q13.31q13.33 probably underlay the abnormal phenotype of the fetus.Genetic analysis can provide crucial information for the prenatal diagnosis and genetic counseling.