2例胎儿15号小额外标记染色体产前遗传学分析

Prenatal genetic analysis of two fetuses with a supernumerary marker chromosome 15

目的:探讨染色体微阵列分析(CMA)诊断15q小额外标记染色体胎儿的临床价值。方法:获得2例高危孕妇的胎儿羊水或脐血细胞及其双亲外周血细胞,通过CMA和G显带染色体核型分析检测胎儿及其父母的染色体结构。结果:胎儿1:羊水细胞G显带核型分析结果为47,XX,+mar,CMA结果为arr15q11.2(22770421-23288350)×4,其父外周血细胞G显带核型分析结果为47,XY,+mar,母亲外周血染色体核型结果及CMA检测结果未见明显异常。胎儿2:脐血染色体G显带分析结果为47,XX,+mar,CMA结果为arr15q11.2q13.3(22770421-32439524)×4,其父母外周血染色体核型结果及CMA分析结果未见明显异常。结论:通过CMA检测和G显带核型分析结果显示,胎儿1存在15q11.2区域的四拷贝重复变异,经鉴定此携带小额外标记染色体为健康人群多态性。胎儿2存在15q11.2q13.3四拷贝重复小额外标记染色体,确诊为15q11.2q13.3微重复四倍体综合征,出生后可能引起较严重的异常表型。本文对两例15号染色体微重复胎儿进行了产前诊断,明确了胎儿基因型与表型的对应关系,为临床产前诊断和遗传咨询提供可靠的依据。

Objective: Prenatal diagnosis of 2 high-risk fetuses by using chromosome Microarray Analysis (Chromosomal Microarray Analysis,CMA).To explore the clinical value of CMA applicating in Supernumerary Marker Chromosome derivative chromosome 15q. Methods: Fetal amniotic fluid or umbilical cord blood and their parents' peripheral blood wers collected.Used G banding and CMA to detect cells of two high risk fetal. Results: Fetus 1:The karyotype analysis results of fetal amniotic fluid was 47,XX,+mar.The result of CMA was arr15q11.2(2770421-23288350) x4.Its father's peripheral blood was 47,XY,+mar.Fetus 2:The karyotype analysis results of fetal umbilical cord blood was 47,XX,+mar.The result of CMA was arr15q11.2q13.3(22770421-32439524)x4. Conclusion: CMA test and G band karyotype analysis showed that there were four copies of repeated variation in 15q11.2 region in fetal 1,which was identified as polymorphism in healthy population.Fetal 2 has 15q11.2q13.3 four copy duplication,and is diagnosed as 15q11.2q13.3 microduplication tetraploid syndrome,which may cause severe abnormal phenotype after birth.In this paper,prenatal diagnosis of two fetuses with microduplication on chromosome 15 was carried out,and the corresponding relationship between fetal genotype and phenotype was clarified,providing reliable basis for clinical prenatal diagnosis and genetic counseling.