摘要目的 探讨全基因组高分辨率染色体微阵列分析(chromosome microarray analysis,CMA)技术在先天性结构异常胎儿中的应用价值.方法 应用美国Affymetrix公司全基因组高分辨率CytoScanHD芯片对651例孕期超声检查提示先天性结构发育异常,但常规染色体核型分析未见异常的胎儿病例进行基因组学研究.包括发生单一畸形者264例,多发畸形者387例.其中产前绒毛样本130例,羊水样本192例,脐血样本329例.全部胎儿样本DNA的提取及CMA实验操作流程均按照生产商提供的标准流程操作.CMA分析所发现的拷贝数变异(copy number variants,CNVs)都进一步通过荧光原位杂交或实时荧光定量PCR反应进行验证.结果 CMA分析发现475例(73％)胎儿的基因组发生拷贝数变异;其中75例(11.5％)胎儿发现与临床疾病相关的致病性CNVs,包括2例单亲二倍体和2例隐匿性的嵌合体;另外13例(2.0％)胎儿病例中发现临床意义不明确的拷贝数变异.结论 全基因组高分辨率CMA在超声结构异常胎儿的遗传学分析中具有重要的应用价值,能够将检出率提高11.5％左右.应用单核苷酸多态性芯片对单亲二倍体和低水平的嵌合体均具有独特的检出能力.实验操作人员和遗传咨询医生之间的充分交流,结合家系分析以及内外数据库之间的比对能够显著降低临床意义不明确的CNVs.

abstractsObjective To assess the value of whole-genome high-resolution chromosome microarray analysis (CMA) for the investigation of fetuses with ultrasound abnormalities.Methods Whole genome high-resolution CytoScanHD array from Affymetrix was employed to investigate 651 fetuses with structural abnormalities detected by ultrasound,for whom standard G-banded chromosome analysis has revealed a normal karyotype.The fetuses were divided into a single malformation group (n=264) and a multiple malformations group (n=387).In total there were 130 chorionic villus samples,192 amniotic fluid samples and 329 cord blood samples.Extraction of fetal DNA and CMA experiment have followed the standard guidelines from the manufacturers.All copy number variations (CNVs) detected by CMA were confirmed by fluorescence in situ hybridization (FISH) or real-time polymerase chain reaction (RT-PCR).Results CMA analysis has detected genomic CNVs in 475 (73％) cases.Clinically significant CNVs were found in 11.5％ (75/651) of fetuses,including two uniparental disomies (UPD) and two cryptic mosaicisms.Variations of unknown significance (VOUS) was found in 2.0％ (13/651) of tested fetuses.Conclusion Above results have suggested that whole-genome and high-resolution CMA is valuable for the analysis of fetuses with structural abnormalities detected by ultrasound,which can increase the detection rate by approximately 11 ％.CMA using single nucleotide polymorphism (SNP) array has the ability to detect UPD and low-level mosaicisms.Sufficient communication between technicians and genetic counselors,parental testing and comparison the results with in-house and relevant online databases can significantly reduce the rate of VOUS.