一例罕见21三体综合征患儿的遗传学分析

Genetic analysis of an infant with rare type of trisomy 21 syndrome

目的应用细胞分子遗传学技术探讨一例罕见21三体综合征患儿的致病原因。方法应用染色体核型分析技术和染色体微阵列技术(chromosomal microarray analysis,CMA)对该21三体综合征患儿进行遗传学分析。结果综合染色体核型结果和染色体微阵列结果,患儿染色体核型为48,XY,+der(X)(Yqter→Yq11.221∷Xp22.31→Xqter),+21.arr[hg19]chr21×3,chrX(7947155-155233098)×2,chrY(16093436-28799654)×2;患儿母亲的核型为46,X,der(X)(Yqter→Yq11.221∷Xp22.31→Xqter).arr[hg19]chrX(168551-2696762)×1,chrY(16107288-28800000)×1。结论核型分析和染色体微阵列分析技术联合应用可精确鉴定患者异常染色体片段来源,本例患儿为一例罕见的21三体综合征患儿,其携带的chrX染色体遗传自母亲。

Objective To investigate the genetic cause for an infant with mental retardation through molecular cytogenetic analysis.Methods Conventional G-banding analysis of peripheral blood for the family was first conducted.Chromosomal microarray analysis(CMA)was performed to further ascertain the size and origin of the abnormal chromosome fragments of the patient.Results We identified a Chinese infant who carries an unbalanced,maternally inherited karyotype 48,XY,+der(X)(Yqter→Yq11.221∷Xp22.31→Xqter),+21 in which karyotype and CMA analyses disclosed Xp22.31→Xqter duplication of 147.3 Mb and Yq11.221→Yq11.23 duplication of 12.7 Mb.Conclusion Accompany with cytogenetic analysis,CMA can accurately identify the origin and size of the abnormal chromosomes,contributing to the precisely genetic analysis.