复杂的嵌合型18号染色体结构异常1例的遗传学分析

Genetic analysis of a case with mosaicism complex structural aberration of chromosome 18

目的探讨1例嵌合型18号染色体结构异常患者的核型。方法选取2019年10月因"结婚4年,未避孕未育2+年"就诊于北医三院生殖中心的1例不育症男性患者作为研究对象,收集其临床资料。取患者外周血样进行染色体核型分析、拷贝数变异(CNV)分析、荧光原位杂交(FISH)检测,同时取患者的精液样本进行单精子CNV分析。结果经检测,确定患者核型为mos 47,XY,del(18)(q21q23),+r(18)(q21q23)[84]/46,XY,del(18)(q21q23)[9]/48,XY,del(18)(q21q23),+r(18)(q21q23)×2[6]/47,XY,del(18)(q21q23),+r(18)(q21q23×2)[1].ish 47,XY,del(18)(q21q23),+r(18)(q21q23)[84]/46,XY,del(18)(q21q23)[9]/48,XY,del(18)(q21q23),+r(18)(q21q23)×2[6]/47,XY,del(18)(q21q23),+r(18)(q21q23×2)[1]del(18)(q21q23)(D18Z1+,18p+,18q+,WCP18+),r(18)(q21q23)(WCP18+),r(18)(q21q23×2)(WCP18+),CNV分析结果未见异常。单精子测序分析发现18条精子中9条为del(18q)(9/20),7条为dup(18q)×2(7/20),2条为dup(18q)×3(2/20),重复或缺失片段大小均为33 Mb。结论该患者携带的18号染色体结构合并数目异常临床比较罕见,尤其是在表型正常的携带者中检测到。通过细胞和分子遗传学的精准诊断,结合单精子拷贝数变异分析,可以进一步评估异常核型对配子生成的影响,从而对生育策略进行精准咨询。

Objective To determine the karyotype of a patient with mosaicism complex structural aberration of chromosome 18.Methods A male patient with a 2-year history of infertility presented at the Center of Reproductive Medicine of the Third Hospital of Peking University in October 2019 was selected as the study subject.Clinical data of the patient was collected.Peripheral blood sample was taken for chromosomal karyotyping,copy number variation(CNV)analysis and fluorescence in situ hybridization(FISH)assay.Semen sample was taken for single sperm CNV analysis.Results The patient was found to have a karyotype of mos 47,XY,del(18)(q21q23),+r(18)(q21q23)[84]/46,XY,del(18)(q21q23)[9]/48,XY,del(18)(q21q23),+r(18)(q21q23)×2[6]/47,XY,del(18)(q21q23),+r(18)(q21q23×2)[1].ish 47,XY,del(18)(q21q23),+r(18)(q21q23)[84]/46,XY,del(18)(q21q23)[9]/48,XY,del(18)(q21q23),+r(18)(q21q23)×2[6]/47,XY,del(18)(q21q23),+r(18)(q21q23×2)[1]del(18)(q21q23)(D18Z1+,18p+,18q+,WCP18+),r(18)(q21q23)(WCP18+),r(18)(q21q23×2)(WCP18+).No pathogenic CNV was identified.Sequencing of 20 single sperms showed that 1 sperm was normal,1 had yielded no result,9 had harbored del(18q),7 had harbored dup(18q)×2,and 2 had harbored dup(18q)×3.The dup/del fragments had both spanned approximately 33 Mb.Conclusion It is rare for carriers of complex structural and numerical abnormalities of chromosome 18 to have a normal phenotype.Based on the accurate cytogenetic and molecular analyses and the single sperm CNV analysis,the influence of the aberrant karyotype on the gametogenesis may be evaluated.