系统胎儿超声联合全外显子测序技术诊断胎儿四肢骨骼发育异常的价值

Diagnostic value of prenatal systematic ultrasonography combined with whole exome sequencing technology for the abnormal skeletal development in four limbs of fetuses

目的:探究系统胎儿超声检查联合全外显子测序(WES)对染色体微阵列(CMA)分析正常,但四肢骨骼发育异常胎儿产前诊断价值。方法:选择2021年3月-2022年1月本院产前妊娠11^(+1)~13^(+6)周时超声提示胎儿颈项透明层(NT)≥3.5mm,行G显带染色体核型分析(KA)、CMA未见明显异常进行WES检测孕妇76例,孕16~18周行系统胎儿超声检查,收集其CMA检测、妊娠结局等资料,分析系统胎儿超声检查联合WES在胎儿四肢体骨骼发育异常中的诊断价值。结果:系统胎儿超声检测结果显示,14例(18.4%)骨骼结构畸形,包括5例多指、3例并趾、3例桡骨短小、2例缺趾、1例足内翻,均终止妊娠且引产证实骨骼系统和肢体异常。WES检出阳性(检出致病性或可能致病性的基因变异)15例(19.7%),以成骨发育不全和软骨发育不全最为常见。以上突变经过Sanger测序予以验证,其中8例胎儿为常染色体显性遗传,突变来源均为新发突变,主要涉及到COL1A1、COL1A2、FGFR3基因;4例胎儿为常染色体隐性遗传,突变来源为父亲或者母亲,3例胎儿突变来源不明。15例胎儿中12例在妊娠16~18周超声发现四肢骨骼异常,3例未发现其他异常,其中13例引产终止妊娠,2例继续妊娠(1例出生后足内翻、1例随访到6月龄发现矮小症);61例WES阴性胎儿中,2例系统超声显示骨骼畸形,59例妊娠16~18周及中晚期超声检测均未发现异常,其中1例终止妊娠,余58例继续妊娠直到分娩,随访至6月龄四肢骨骼生长发育均正常。结论:胎儿系统超声联合胎儿WES技术,可对染色体正常但四肢骨骼发育异常的胎儿进行有效产前诊断,减少孕妇等待时间。

Objective:To explore the value of prenatal systematic ultrasonography combined with whole exome sequen-cing(WES)technology for diagnosing fetuses with normal karyotype by chromosome microarray analysis(CMA)and with abnormal skeletal development in four limbs by ultrasonography.Methods:From March 2021 to January 2022,a total of 76 pregnant women with fetal nuchal translucency(NT)≥3.5 mm by ultrasound scan during 11^(+1)-13^(+6) gestational weeks,but the chromosomes by G banding karyotype analysis(KA)and the CMA of these fetuses were normal.The fetuses of these women were further given WES technology,and the systematic fetal ultrasonography was performed on these fetuses during 16-18 gestational weeks.The data of the CMA and the pregnancy outcomes of these fetuses were collected.The value of prenatal systematic ultrasonography combined with WES technology for diagnosing abnormal skeletal development in four limbs of the fetuses was analyzed.The results of systematic fetal ultrasonography showed that there were 14(18.4%)cases with skeletal structure malformations,including 5 cases of polydactyly,3 cases of syndactyly,3 cases of radius short,2 cases of missing toe,and 1 case of varus,and which were all confirmed of abnormalities of skeletal system and limb after terminated pregnancy of induced labor.There were 15(19.7%)cases with positive WES(pathogenic or potentially pathogenic gene mutation),and the osteogenic dysplasia and achondroplasia were the most common.These 15 fetuses with gene mutation were verified by Sanger sequencing.There were 8 fetuses with autosomal dominant,and the sources of the mutations were all new mutations,mainly involving COL1A1,COL1A2,and FGFR3 genes.There were 4 fetuses with autosomal recessive inheritance,and the sources of the mutations were from father or mother.There were 3 fetuses with mutation unknown cases,and the source of the mutation was unknown.In the 15 fetuses with positive WES(detected the pathogenic or possibly patho-genic gene mutation),there were 12 fetuses with skeletal abnormalities in the limbs and 3 fetuses without abnormalities by systematic fetal ultrasound during 16-18 gestational weeks.Among them,13 fetuses were given terminate pregnancy by induced,and 2 fetuses were continued pregnancy,which included 1 newborn with strephenopodia confirmed after birth and 1 newborn with nanism of the results of follow-up to 6 months after born.Among the 61 fetuses with negative WES,2 cases had been showed bone malformations by systematic ultrasound,and the other 59 cases had showed no abnormalities by ultrasound examination during 16-18 gestational weeks and during the second and the third trimester of pregnancy.In the 59 cases without abnormalities by ultrasound examination,1 case terminated pregnancy,and the other 58 cases were continued pregnancy until delivery and were followed up to 6 months after delivery,with normal growth and normal development of limbs bone.Conclusion:Prenatal systematic ultrasonography combined with WES technology can provide effective prenatal diagnosis for the fetuses with normal karyotype and abnormal skeletal development in four limbs,so as to shorten the waiting time of the pregnant women.