目的 明确孕妇宫内双胞胎的遗传信息和发育情况，为产前诊断及遗传咨询提供依据。方法 对孕妇实施羊膜穿刺术，获得羊水胎儿脱落细胞，利用染色体核型分析、SNP array和FISH技术获得胎儿遗传信息，并根据超声评价其胎儿宫内发育情况。同时抽取孕妇夫妇、孕妇的儿子和父母的外周血，进行染色体核型分析和SNP array检测。并于孕妇孕29周时，进行胎儿系统超声检查。结果 胎儿染色体核型分析提示该双胞胎都有一条衍生的4号染色体，SNP array提示胎儿是7q11.23q21.3三体，FISH提示衍生的4号染色体是由片段7q11.23q21.3插入4号染色体长臂所致。在外周血的检测中，我们发现孕妇、孕妇儿子及其母亲都是7q11.23q21.3三体的携带者，其他人未见异常。孕妇29周的超声结果提示胎儿存在室间隔缺损。结论 双胞胎的7q11.23q21.3三体遗传于母亲，家族中的携带者表型都正常，提示胎儿表型正常可能性极高。导致室间隔缺损的原因十分复杂，与7q11.23q21.3三体是否有关无法确定，基于缺损很小，且目前手术能够修复，我们建议孕妇继续妊娠，并定期进行超声监测。
Objective Determine the genetic information and development of two fetuses and provide the basis for prenatal diagnosis. Method Fetal shedding epithelial cells was obtained by amniocentesis. Chromosome karyotype analysis, SNP array and FISH were performed in the fetuses. The development of two fetuses was evaluated by ultrasound. At the same time, the peripheral blood coming from the parents of two fetuses, the son and the parents of the pregnant woman were collected for chromosome karyotype analysis and SNP array analysis. About 29 weeks of gestation, the woman took fetal ultrasound examination systematically and roundly. Results Karyotype analysis suggests two fetuses have a derivative chromosome 4, SNP array suggests two fetuses have trisomy 7 q11.23 q21.3, FISH suggests that 7q11.23q21.3 insert in chromosomes 4 long arms, which generates derivative chromosome 4 . In the peripheral blood detection, we found that the pregnant woman, her son and her mother were all carriers of trisomy 7q11.23q21.3. However, all these carriers are normal. Ultrasound examination demonstrated two fetuses both had ventricular septal defect at 29 weeks of gestation. Conclusions The trisomy 7q11.23q21.3 of two fetuses is inherited from their mother, and the carriers in the family all have normal phenotype, indicating that two fetuses have the probability of normal phenotype is very high. Due to the causes of ventricular septal defect are complex, we are not sure that ventricular septal defect is associated with trisomy 7 q11.23 q21.3. Basing on the small defect and the mature operation, we recommend that pregnant woman could continue her pregnancy, and take ultrasound examinations regularly to observe two fetuses.
