21例产前超声高度怀疑先天性骨骼系统畸形胎儿的遗传学分析

Genetic analysis of 21 fetuses with high suspicion of congenital skeletal malformation by prenatal ultrasound

目的探讨产前超声提示骨骼系统畸形胎儿的遗传学病因。方法回顾性纳入2019年1月至2020年8月就诊于河南省人民医院医学遗传研究所的产前超声高度怀疑胎儿骨骼系统畸形的孕妇21例(孕妇和配偶均无骨骼系统畸形),抽取羊水/脐带血、孕妇及其配偶外周血,行染色体核型分析、染色体微阵列分析或全外显子组测序,并对全外显子组测序检出的“致病性”“可疑致病性”“临床意义未明”变异行Sanger测序验证。采用描述性统计分析总结骨骼系统畸形胎儿的遗传学病因。结果染色体核型分析检出染色体异常5例(21-三体4例,18-三体1例)。染色体微阵列分析检出拷贝数变异异常1例(16p11.2微缺失综合征)。全外显子组测序检出单基因病10例,累及8个基因(SGMS2、FGFR3、DYNC2H1、WDR35、TBX5、COL2A1、FGFR2、ALPL);检出14个基因变异,包括7个数据库未报道过的新变异(DYNC2H1基因c.8129T>A、c.7126G>A、c.10307_10320del、c.2641G>T,WDR35基因c.3085G>A、c.491G>A,COL2A1基因c.1070G>T)。结论对于孕妇和配偶均无骨骼系统畸形但产前超声检查高度怀疑先天性骨骼系统畸形的胎儿,遗传因素是其先天性骨骼系统畸形的重要原因,主要包括染色体异常、拷贝数变异异常和单基因病。

Objective To explore the genetic etiology of fetuses with high suspicion of congenital skeletal malformation detected by prenatal ultrasound.Methods This retrospective study collected 21 pregnant women with highly suspected fetal skeletal malformation indicated by ultrasound(the couples had no skeletal malformation)at Institute of Medical Genetics,Henan Provincial People's Hospital from January 2019 to August 2020.Amniotic fluid/umbilical cord blood of the fetus and peripheral blood of the couples were obtained for karyotype analysis,chromosomal microarray analysis,and whole-exome sequencing.Sanger sequencing was performed for the"pathogenic""suspected pathogenic""variants of uncertain significance"variants detected by whole exome sequencing.Genetic etiology of the 21 fetuses was described.Results A total of five chromosomal abnormalities were detected,including four cases of trisomy 21 and one trisomy 18.Chromosome microarray analysis detected one case of abnormal copy number variation,16 p11.2 microdeletion syndrome.Ten cases of monogenic diseases were found by whole exome sequencing and eight genes were involved(SGMS2,FGFR3,DYNC2H1,WDR35,TBX5,COL2A1,FGFR2,and ALPL).Totally,14 variations were detected,among which seven were novel variations(c.8129T>A,c.7126G>A,c.10307_10320del,and c.2641G>T in DYNC2H1 gene;c.3085G>A and c.491G>A in WDR35 gene;c.1070G>T in COL2A1 gene).Conclusions For fetus,whose parents have no skeletal malformation,highly suspected of congenital malformation of skeletal system by prenatal ultrasound,genetic factor is the primary reason,including chromosomal abnormalities,copy number variations,and monogenic mutations.