母源性平衡易位t(6;14)所致胎儿不平衡易位1例的分析

Analysis of a fetus with unbalanced translocation derived from a balanced t (6;14) maternal translocation

目的探讨1例孕中期血清学筛查提示高风险胎儿的遗传学特征。方法该孕妇于2020年3月22日因"血清学筛查高风险"就诊于河南省人民医院。采用常规G显带染色体核型分析和微阵列比较基因组杂交(aCGH)对胎儿及孕妇夫妇进行检测。结果胎儿G显带染色体核型为46,XX,der(6)t(6;14)(q27;q31.2),孕妇核型为46,XX,t(6;14)(q27;q31.2),其丈夫核型未见异常。胎儿aCGH结果显示染色体6q26q27区存在6.64 Mb的缺失,14q31.3q32.33区存在19.98 Mb重复,均判断为致病性拷贝数变异。孕妇夫妇aCGH结果未见异常。结论胎儿的不平衡染色体异常可能缘于孕妇携带的平衡易位。aCGH有利于确定胎儿染色体异常的类型及断裂点,为预测胎儿发生畸形的风险及后续妊娠的选择提供依据。

Objective To explore the genetic characteristics of a fetus with a high risk by maternal serum screening in the second trimester.Methods Genetic counseling was provided to the pregnant woman on March 22,2020 at Henan Provincial People's Hospital.G-banded chromosomal karyotyping and array comparative genomic hybridization(aCGH)were carried out for the amniotic fluid sample and peripheral blood samples from the couple.Results The fetus and the pregnant woman were respectively found to have a 46,XX,der(6)t(6;14)(q27;q31.2)and 46,XX,t(6;14)(q27;q31.2)karyotype,whilst the husband was found to have a normal karyotype.aCGH analysis identified a 6.64 Mb deletion at 6q26q27 and a 19.98 Mb duplication at 14q31.3q32.33 in the fetus,which were both predicted to be pathogenic copy number variations.No copy number variation was found in the couple.Conclusion The unbalanced chromosome abnormalities in the fetus have probably derived from the balanced translocation carried by the pregnant woman.aCGH can help to determine the types of fetal chromosome abnormalities and the site of chromosomal breakage,which may facilitate the prediction of fetal outcome and choice for subsequent pregnancies.