产前BAC-on-Beads技术在性染色体非整倍体异常和性染色体微缺失/微重复诊断中的应用研究

Application of prenatal BAC-on-Beads technology in sex chromosome aneuploidy abnormality and chromosome microdeletion/micro-repetition diagnosis

目的通过产前BAC-on-Beads技术对胎儿性染色体非整倍体和性染色体微缺失的检测,结合胎儿染色体核型分析和胎儿染色体全基因组微阵列分析(chromosomal microarray analysis,CMA)检测,以探讨Bo Bs技术用于检测胎儿性染色体非整倍体和微缺失/微重复检测的可行性。方法将2016年4月-2017年6月采集到的1576例具有产前诊断指征的单胎孕妇羊水,同时行产前Bo Bs与传统羊水染色体G显带核型分析,结合CMA验证并比较染色体异常的检测结果。结果在1576例羊水样本中,产前Bo Bs技术共检测出性染色体非整倍体异常14例:其中X探针检测区扩增异常减少2例;X探针检测区扩增异常增加7例;Y探针检测区扩增异常增多2例,X/Y探针检测区扩增异常增多1例;传统染色体核型结果为:1例45,XO;2例47,XXX;4例47,XXY;4例47,XYY;3例不同比例的性染色体嵌合体(嵌合比例均>20%),与Bo Bs检测提示结果均一致。产前Bo Bs检出11例性染色体的微缺失/微重复分别是:3例Yq11的缺失,4例Xp22的缺失;1例Xp22.33q28大片段的重复/缺失;经CMA验证:3例Yq11.23区段380Kb、395Kb、928.8Kb缺失;3例Xp22.31区段1.68Mb、1.5Mb、1.68Mb缺失;1例Xp22.33~p22.2片段12.8Mb缺失;1例Xp22.33~q28大片段的7.7Mb缺失、33.5Mb和106.4Mb的重复,3例拒绝验证。但只有2例Bo Bs检测染色体核型分析能辨析。结论产前Bobs技术可以准确检测出性染色体非整倍体异常,包括嵌合比例>20%的染色体核型;核型分析只能检测出性染色体>10Mb缺失/重复,而产前Bo Bs结合CMA验证可以准确检测出性染色体微缺失/微重复,且能较全面的检测胎儿性染色体异常,预防出生缺陷。

Objective：To detect the chromosomal aneuploidy and chromosome microdeletions by prenatal BAC-on-Beads technique,combined with fetal chromosome karyotype analysis and chromosomal microarray analysis（CMA））To explore the feasibility of Bo Bs technology for the detection of fetal sex chromosomes aneuploidy and microdeletion/micro-repeat detection. Methods：A total of 1576 singleton pregnant women with prenatal diagnosis indications were collected from April to June in 2016 in June,2017. At the same time,prenatal Bo Bs and traditional amniotic fluid chromosome G were karyotype analysis,combined with CMA validation and comparison Chromosome aberration test results. Results：Of the 1576 cases of amniotic fluid,14 cases of sex aneuploidy abnormality were detected in prenatal Bo Bs technique：2 cases were abnormal in X-probe detection area,7 cases were abnormal in X-probe detection area;Y-probe detection area increased abnormality in 2 cases,X-Y probe detection area increased abnormality in 1 case;the traditional chromosome karyotype results：1 case 45,XO;2 cases 47,XXX;4 cases 47,XXY;4 cases 47,XYY;3 cases of different proportion of sex chromosome chimera（chimeric ratio 20%）,and Bo Bs detection results are consistent. Pretreatment of Bo Bs in 11 cases of chromosome microdeletions/micro-duplication were：3 cases of Yq11 deletion,4 cases of Xp22 deletion;1 case of Xp22.33 q28 large fragments of the duplication/deletion;by CMA validation：3 cases of Yq11. 23 cases of 380 Kb,395 Kb and 928.8 Kb were absent;3 cases of Xp22.31 segment 1.68 Mb,1.5 Mb,1.68 Mb deletion;1 case Xp22.33 ~ p22.2 fragment 12.8 Mb deletion;1 case Xp22.33 ~ q28 large Fragment of 7.7 Mb deletion,33.5 Mb and 106.4 Mb of repeat,3 cases refused to verify. But only 2 cases of Bo Bs were tested for chromosome karyotype analysis. Conclusion：Prenatal Bobs technique can accurately detect chromosomal aneuploidy abnormalities,including chromosome karyotype with a chimeric ratio of 20%;karyotype analysis can only detect sex chromosome 10 Mb deletion/repetition,and prenatal Bo Bs binding CMA validation can accurately detect sex chromosome microdeletions/micro-repeat,and can be more comprehensive detection of fetal chromosomal abnormalities,prevention of birth defects.