Application of single nucleotide polymorphism microarray combined with chromosomal karyotype analysis in prenatal diagnosis
Objective:To evaluate the application of G-banding karyotype analysis combined with single nucleotide polymorphism microarray(SNP array)technology in prenatal diagnosis of amniotic fluid,and provide evidence for clinical diagnosis and genetic counseling.Methods:A total of 837 pregnant women with prenatal diagnosis indications were selected.After obtaining informed consent,amniotic fluid was collected for G-banding karyotype analysis and SNP-array detection,and the test results were analyzed.Results:The abnormal detection rates of karyotyping,SNP-array,and the combined application were 11.11%,13.14%,and 14.70%,respectively.According to different prenatal diagnostic indications,the abnormal detection rates of karyotyping and SNP-array were the highest in the high-risk group of NIPT(non-invasive prenatal testing).The second highest was the fetal ultrasound abnormality group.SNP-array detected all 59 cases of fetal chromosomal number abnormalities found by karyotype analysis.SNP-array detected copy number variations(CNVs)in 30 fetuses missed by karyotype analysis.In addition,SNP-array could identify the source of unknown fragments.There were 10 cases of abnormal karyotype analysis but missed by SNP-array,including 8 cases of balanced translocation or inversion,and 2 cases of mosaicism.The 10 cases of mosaicism detected by SNP-array were all consistent with the result of karyotype analysis.There were 10 cases of abnormal karyotype analysis but missed by SNP-array,including 8 cases of balanced chromosomal translocation or inversion,and 2 cases of mosaicism.Among the 123 cases with abnormal karyotype analysis detected by combined analysis,79 cases were selected for termination of pregnancy by genetic counseling,44 cases were selected for continuation of pregnancy,and 44 cases were successfully born.These cases were followed up to 1 year after birth,and no cases inconsistent with the prenatal diagnosis results were found.Conclusions:Both G-banding karyotype analysis and SNP array technology have their own advantages and disadvantages.The combined application can significantly improve the detection rate of chromosome abnormalities in prenatal diagnosis,thus providing better evidence for clinical diagnosis and genetic counseling.
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