Application of karyotype analysis combined with other genetic testing techniques in prenatal diagnosis of pregnant women at an advanced maternal age
Objective To investigate the potential of karyotype analysis combined with single nucleotide polymorphism(SNP)array,or fluorescence in situ hybridization(FISH),or bacterial artificial chromosomes(BACs)-on-Beads(BoBs)technology in prenatal diagnosis of pregnant women at an advanced maternal age.Methods A total of 930 pregnant women who received prenatal diagnosis due to an advanced maternal age were retrospectively studied.All of them underwent karyotype analysis,including 420,343 and 167 cases tested by karyotype analysis combined with BoBs,SNP array,and FISH,respectively.Chromosomal results and pregnancy outcomes were analyzed.Results Among 930 fetuses,192 cases(20.7%)had an abnormal karyotype,with the trisomy 21 and Klinefelter syndrome as the predominant trisomy syndrome and sex chromosome abnormality,respectively.Karyotype analysis combined with SNP array significantly enhanced the detection rate of fetal chromosomal abnormalities than that in combination with other tests(χ2=6.191,P=0.013).For the diagnosis of chromosomal chimerism,karyotype combined with FISH could more accurately determine the type and proportion of chimerism.The risk of chromosomal abnormalities in isolated fetuses delivered by pregnant women at an advanced maternal age was relatively low,which was the highest in high-risk fetuses examined by noninvasive prenatal testing with their mothers at an advanced maternal age.In the combination of soft ultrasound markers and advanced maternal age,the rate of chromosomal abnormalities increased with the increasing number of soft ultrasound markers(P=0.001).There was a positive correlation of the age of pregnant women at an advanced maternal age with the incidence of abnormal karyotype,aneuploidy,especially trisomy 21(P＜0.05).Conclusion The risk of chromosomal abnormalities in isolated fetuses delivered by pregnant women at an advanced maternal age is relatively low,but it is high in high-risk fetuses examined by noninvasive prenatal testing with their mothers of advanced maternal.The risk of chromosomal abnormalities in fetuses increases with the increased number of soft ultrasound markers and the age of pregnant women.Karyotype analysis combined with FISH can more accurately determine the type and proportion of chimerism,which,combined with other tests,especially SNP array,can significantly improve the detection rate of chromosomal abnormalities.Karyotype analysis is conducive to genetic counseling and fertility guidance,and it is the preferred prenatal diagnosis program for pregnant women at an advanced maternal age.
pregnant women at an advanced maternal agekaryotype analysissingle nucleotide polymorphism(SNP)arraybacterial artificial chromosomes(BACs)-on-Beads(BoBs)technologyfluorescence in situ hybridization(FISH)technology
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