SNP芯片检测胎儿额外小标记染色体的研究*

目的 总结应用SNP芯片技术对胎儿额外小标记染色体（sSMC）进行鉴定的经验，为产前遗传咨询提供参考。方法 应用传统G显带技术对2例胎儿羊水细胞及其父母外周血进行染色体核型分析，进一步用SNP芯片技术明确胎儿sSMC的来源。结果 1号胎儿羊水染色体核型为45，X[74]/46，X，+mar[31]，芯片扫描结果为Xp22.33～p11.22和Xq27.3～q28区域均缺失，缺失大小分别为52.7和8.6?Mb。2号胎儿羊水染色体核型为47，XX，+mar，芯片结果为46，XX，其父亲外周血染色体核型为47，XY，+mar，临床表型正常。结论 SNP芯片可以确定sSMC的来源，可作为传统核型分析的补充，为产前诊断和遗传咨询提供帮助。

Detection of small supernumerary marker chromosomes infetuses by SNP chip*

Objective To evaluate the diagnostic value of small supernumerary marker chromosomes (sSMC) by SNP chip technique applied in two fetuses. Methods The karyotypes of two fetuses and their parents were analyzed by conventional G banding technique. SNP chip technique was performed to determine the source of sSMC. Results The chromosome karyotype of fetus 1 was determined as 45, X[74]/46, X, +mar[31]. The chip has identified of a 52.7?Mb deletion at Xp22.33-p11.22 and of a 8.6?Mb deletion at Xq27.3-q28. The karyotype of Fetus 2 was 47, XX, +mar, while the chip result was 46, XX. Patriarchal karyotype was 47, XY, +mar with normal clinical characteristics. Conclusions The SNP chip is able to determine the source of sSMC and serves as supplementation to traditional karyotype analysis for prenatal diagnosis and genetic counseling.