13号环状染色体1例的产前遗传学诊断

Prenatal genetic diagnosis of a case with ring chromosome 13

目的对1例无创产前检测(NIPT)提示的胎儿13号染色体复杂环状结构异常进行细胞及分子遗传学分析。方法选择2021年5月11日就诊于中国医科大学附属盛京医院的1例孕妇作为研究对象,抽取其外周血样进行NIPT筛查,对羊水细胞及孕妇夫妇的外周血样进行G显带染色体核型分析。对孕妇外周血样和羊水细胞同时进行基因组拷贝数变异测序(CNV-seq)、染色体微阵列分析(CMA)和荧光原位杂交(FISH)检测。结果NIPT检测提示胎儿13号染色体存在单体嵌合或片段缺失。G显带分析提示胎儿与孕妇的染色体核型均为47,XX,der(13)(pter→p11::q22→q10),+r(13)(::p10::q22→qter::),孕妇丈夫核型未见异常,FISH证实了上述结果。CNV-seq和CMA检测胎儿和孕妇均未见明显异常。结论本研究胎儿的13号环状染色体遗传自孕妇,但未合并缺失、重复、嵌合体等异常。孕妇本人及胎儿产前超声诊断均未见明显异常。

Objective To carry out cyto-and molecular genetic analysis for a fetus with a ring chromosome identified through non-invasive prenatal testing(NIPT).Methods A pregnant woman presented at the Shengjing Hospital Affiliated to China Medical University on May 11,2021 was selected as the study subject.Maternal peripheral blood sample was screened by NIPT,and G-banded chromosomal karyotyping was carried out on amniotic fluid and peripheral blood samples from the couple.The fetus and the pregnant woman were also subjected to genomic copy number variation sequencing(CNV-seq),chromosomal microarray analysis(CMA),and fluorescence in situ hybridization(FISH)assay.Results NIPT result suggested that the fetus had monomeric mosaicism or fragment deletion on chromosome 13.G banded chromosomal analysis showed that both the fetus and its mother had a karyotype of 47,XX,der(13)(pter→p11::q22→q10),+r(13)(::p10::q22→qter::),whilst her husband had a normal karyotype.FISH has verified the above results.No abnormality was detected with CNV-seq and CMA in both the fetus and the pregnant woman.Conclusion The ring chromosome 13 in the fetus has derived from its mother without any deletion,duplication and mosaicism.Both the fetus and the pregnant woman were phenotypically normal.