一例母源性46,Y,der(X)t(X;Y)(p22;q11)染色体非平衡易位患儿的遗传学分析

目的对1例临床表征为身材矮小、鼻根部内陷、双侧隐睾、智力低下患儿进行遗传学分析,探讨该染色体结构异常与临床表征之间的关系。方法应用G显带染色体核型分析及染色体微阵列分析(chromosomal microarray analysis,CMA)技术对患儿进行遗传学检测,并对其父母进行外周血染色体核型分析。结果G显带分析结果显示患儿染色体核型为46,Y,der(X)t(X;Y)(p22;q11),mat。CMA检测结果提示患儿X染色体短臂Xp22.33p22.31存在约8.3 Mb片段缺失,Y染色体长臂Yq11.221qter存在约43.3 Mb片段重复。其父亲染色体核型正常,母亲染色体核型结果为46,X,der(X)t(X;Y)(p22;q11)。结论患儿携带母源性der(X)t(X;Y)(p22;q11)染色体非平衡易位,携带者的表型与其性别以及X染色体缺失片段的大小和位置密切相关。男性携带者智力障碍、生长发育落后等异常表型较女性更为严重。

Genetic study of a child carrying a maternally derived unbalanced 46,Y,der(X)t(X;Y)(p22;q11)chromosomal translocation

Objective To explore the genetic basis for a child featuring short stature,saddle nose,cryptorchidism and mental retardation.Methods The child and his parents were subjected to G-banded karyotyping and chromosomal microarray analysis(CMA).Results The child was found to have a 46,Y,der(X)t(X;Y)(p22;q11)mat karyotype.CMA revealed a 8.3 Mb deletion at Xp22.33p22.31 and a 43.3 Mb duplication at Yq11.221qter.His mother had a karyotype of 46,X,der(X)t(X;Y)(p22;q11).His father had a normal karyotype.Conclusion The child has carried an unbalanced translocation der(X)t(X;Y)(p22;q11)derived from his mother.His clinical phenotype has correlated with the size and position of X chromosome deletion.Compared with the females,abnormal phenotypes such as mental retardation and growth retardation of male carriers are more severe.