摘要目的:探讨5例遗传物质不一致的单绒毛膜双羊膜囊(MCDA)双胎的遗传学病因。方法:选取2016年1月至2020年6月于广西壮族自治区妇幼保健院产科进行双胎羊膜腔穿刺产前诊断的148例MCDA双胎为研究对象。收集孕妇的临床资料，分别采集双胎的羊水样本进行染色体核型分析及单核苷酸多态性微阵列(SNP array)检测。结果:染色体核型分析显示，148例MCDA双胎中有5例染色体核型不一致，发生率为3.4%(5/148)。SNP array检测显示其中3例胎儿为嵌合体。结论:MCDA双胎存在遗传物质不一致的现象，其产前诊断需具有丰富经验的医学遗传学和胎儿医学专家共同完成，临床处理应该遵循个体化原则。

abstractsObjective:To explore the genetic etiology of 5 cases of monochorionic-diamniotic (MCDA) with genetic discordance.Methods:148 cases of MCDA twins who were diagnosed by amniocentesis at the Maternal and Child Health Care Hospital of Guangxi Zhuang Autonomous Region from January 2016 to June 2020 were selected as the study subjects. Relevant clinical data of the pregnant women were collected, and amniotic fluid samples of the twins were collected separately. Chromosomal karyotyping analysis and single nucleotide polymorphism array (SNP array) assay were carried out.Results:The results of chromosomal karyotyping analysis showed that 5 of the MCDA twins had inconsistent chromosome karyotypes, with an incidence of 3.4% (5/148). SNP array assay showed that 3 fetuses were mosaics.Conclusion:Genetic discordance occurs among MCDA twins, and prenatal counseling for such cases should be given by doctors with experience in medical genetics and fetal medicine, and personalized clinical management should be recommended.