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目的:探讨单核苷酸多态性芯片(SNP array)在唐氏筛查高风险孕妇胎儿染色体分析中的应用价值。方法:选取312例因唐氏筛查高风险的孕妇,行羊膜腔穿刺术后获得羊水,对羊水进行G显带核型分析和SNP array检测,比较核型分析与SNP array检测结果,并按年龄分组比较拷贝数变异(CNVs)的发生率差别。结果:核型分析和SNP array均准确发现2例21三体(0.64%),6例核型分析提示染色体平衡重组(1.92%)的样本经SNP array分析证实不存在重排片段重复或缺失。在303例核型正常的胎儿羊水细胞中,SNP array检测发现176例CNVs,其中良性CNVs 106例,临床意义不明确的CNVs(VOUS)61例,新发CNVs(de novo CNVs)9例,未发现已知的致病性CNVs。唐氏筛查高风险组与唐氏筛查高风险合并高龄组CNVs的分布差别无统计学意义(P>0.05)。此外,本研究中首次报道14种CNVs。结论:SNP array可进一步确定核型分析的平衡易位是否存在染色体微缺失/重复。在核型正常的胎儿中,SNP array可检测出大量拷贝数异常,发现14种新的CNVs但现有数据库无法判断其临床意义,需进一步研究确认。此外,孕妇年龄对胎儿基因组中新发CNVs的发生率无明显影响。
Objective: To investigate the value of single nucleotide polymorphism (SNP) array in fetal chromosomal analysis of Down’s screening high-risk pregnant women. Methods: A total of 312 pregnant women with high risk of Down’s disease screening were selected. Amniotic fluid was obtained after amniocentesis. G - banding karyotype analysis and SNP array detection of amniotic fluid were performed. Karyotype analysis and SNP array test results were compared. Age group differences in copy number variation (CNVs) incidence. Results: Two cases of trisomy 21 (0.64%) were found by karyotype analysis and SNP array analysis. The karyotype analysis of 6 cases showed that chromosome rearrangement (1.92%) was confirmed by SNP array analysis. No duplication or deletion of rearranged fragments was found. Of the 303 normal fetal amniotic fluid cells, 176 CNVs were detected by SNP array, of which 106 were benign CNVs, 61 with clinically significant CNVs (VOUS), 9 with de novo CNVs, 9 Known pathogenic CNVs were found. There was no significant difference in the distribution of CNVs between Down’s screening high risk group and Down’s screening high risk combined elderly group (P> 0.05). In addition, 14 CNVs were first reported in this study. Conclusion: The SNP array can further confirm the presence or absence of chromosomal microdeletions / duplications in the equilibrium translocation of the karyotype analysis. In normal karyotype fetus, SNP array can detect a large number of copy number anomalies, found 14 kinds of new CNVs but the existing database can not determine its clinical significance, further study confirmed. In addition, the age of pregnant women had no significant effect on the incidence of new CNVs in the fetal genome.