一例以精神发育迟滞为主要临床表现的XYY综合征患儿的遗传学分析

Genetic analysis of a child with XYY syndrome mainly featuring mental retardation

目的对1例精神发育迟滞患儿及其父母进行遗传学分析，寻找其致病原因。方法对患儿及其父母进行常规染色体G显带核型和荧光原位杂交技术分析，再以染色体微阵列分析技术对该患儿进行检测，并以定量PCR对可疑突变进行检测验证。结果染色体核型分析与荧光原位杂交结果确定患儿为47，XYY，未见其他染色体异常，其父母核型正常；染色体微阵列分析结果显示患儿X染色体单拷贝缺失，Y染色体探针覆盖区呈双拷贝重复，同时发现一可疑致病基因KYNU的片段缺失。结论当染色体畸变综合征表型异质性时，应进一步应用精度更高的染色体微阵列进行遗传学检查，以寻找其它可能并存的导致表型变异的染色体微缺失／微重复。

Objective To explore the genetic cause for a boy featuring mainly with mental retardation. Methods G-banding karyotyping and fluorescence in situ hybridization （FISH） were carried out for the child and his parents. The child was also analyzed with chromosome microarray （CMA）. Suspected microdeletion was validated with quantitative PCR, Results The proband was found to have a 47,XYY karyotype by both chromosome and FISH analyses, while both of his parents had a normal karyotype. CMA suggested that the proband had one copy of X chromosome and two copies of Y chromosome. In addition, CMA has also detected deletion of the KYNU gene （mapped at 2q22.2）, which could be pathogenic. The result was confirmed by qPCR. Conclusion For its high resolution, CMA can be used to identify potential microdeletion/duplications among children with chromosome aneuploidy and unusual phenotypes.