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目的探讨同卵双胎染色体异常产前检测的最适样本类型及同卵双胎的发生机制。方法对1例因唐氏筛查高风险的双胎妊娠孕妇行羊膜腔穿刺取羊水样本,用定量荧光PCR(quantitative fluorescent PCR,QF-PCR)检测常见染色体非整倍体,核型分析方法检测染色体病。结果 QF-PCR提示双胎为同卵双胎,胎儿A性染色体为:XY,胎儿B性染色体为:XO;染色体核型分析结果显示胎儿A为:46,XY,胎儿B为:45,XO。两种检测方法均未检测到任何一胎羊水样本有:46,XY/45,XO嵌合现象。结论在产前诊断中,羊水样本比绒毛及脐血样本更适合用于同卵双胎胎儿的染色体检测。胚胎发育早期部分细胞染色体分离错误导致胚胎出现两个染色体不同的细胞系可能是同卵双胎发生的重要原因。
Objective To investigate the optimal sample type and the mechanism of the identical twins in prenatal testing of identical twins chromosomal abnormalities. Methods Amniotic fluid samples were obtained from amniocentesis in 1 pregnant women who were at high risk of screening for Down’s syndrome. Common aneuploidies were detected by quantitative fluorescent PCR (QF-PCR) and karyotype analysis Chromosomal disease. Results QF-PCR showed that twins were identical twins, fetus A sex chromosomes were XY, fetus B sex chromosomes were XO, chromosome karyotype analysis results showed that fetus A was 46, XY, fetus B was 45, XO . No detection of any one of the two methods of detection of a fetal amniotic fluid samples are: 46, XY / 45, XO chimerism. Conclusions In prenatal diagnosis, amniotic fluid samples are more suitable for chromosomal detection of identical twin fetuses than villus and umbilical cord blood samples. The early part of embryonic development of chromosome segregation error resulting in embryos appear two different chromosomal cell lines may be an important cause of identical twins.