| ObjectiveTo investigate the relationship between different prenatal diagnostic indications and fetal abnormal karyotypes;to explore the application value of cell and molecular genetic techniques such as karyotype analysis,chromosome microarray analysis,fluorescence in situ hybridization in prenatal diagnosis.MethodsA total of 3226 pregnant women who underwent prenatal diagnosis at the prenatal diagnosis center between Jan l,2014 and Dec 31,2018 were collected.After signing informed consent,3117 pregnant women with prenatal diagnosis indications were subjected to amniocentesis for amniotic fluid karyotype analysis;109 pregnant women with prenatal diagnosis indications were performed karyotype analysis of cord blood.1 Statistical analysis:the relationship between prenatal diagnostic indications and fetal abnormal karyotype type was analyzed.the chromosomal abnormality detection rate of different prenatal diagnosis indications was statistical analyzed using chi-square test by CHISS software,difference was statistically significant when p<0.05.2 Molecular genetic analysis:small marker chromosomes and unclear structural abnormalities found by karyotype analysis were further diagnosed by fluorescence in situ hybridization or chromosome microarray analysis to identify the source and nature of anomalous fragments.Result1.In 3226 cases of pregnant women with amniotic fluid/umbilical cord blood karyotype analysis,a total of 289 fetal chromosomal abnormalities(excluding chromosomal polymorphisms)were detected,with the detection rate of 8.96%.128 cases of 21-trisomy were detected as major abnormal karyotype,,accounting for 44.29%of the total abnormal karyotypes;26 cases of 18 trisomy(9.00%),4 cases of 13 trisomy(1.38%),54 cases of abnormal sex chromosome(including chimera)(18.69%),36 cases of inversion(12.46%),24 cases of translocation(8.30%),2 cases of deletion(0.69%),1 case of isochromosome(0.35%),2 cases of dicentric chromosome(0.69%),1 case of derived chromosome(0.35%),5 cases of marker chromosome(1.73%),and 6 cases of abnormal karyotypes with unclear abnormal structure(2.08%)were detected.2.Of the 3226 cases of amniotic fluid/umbilical cord blood karyotype analysis,3012 cases(93.37%)in the single indication group,210 cases(6.51%)in the two indications group,and 4 cases(0.12%)in the three indications group.205 cases,81 cases,and 3 cases of abnormal karyotypes were detected with detection rate of 6.81%,38.57%,and 75.00%respectively.The detection rates of abnormal karyotypes in the two indications group and the three indications group were significantly higher than that in the single indication group with statistically significant difference(p<0.05).3.Among 3012 cases in single-indication group,of 1640 cases(50.84%)in the age group,913 cases(28.30%)in the serological screening high risk group,227 cases(7.04%)in the ultrasound abnormal group,and 102 cases in the adverse pregnancy history group(3.16%),94 cases(2.91%)in the NIPT positive group and 36 cases(1.12%)in the parental chromosomal abnormality group,61 cases,42 cases,29 cases,1 case,53 cases,19 cases of abnormal karyotypes were detected with detection rates 3.72%,4.60%,12.78%,0.98%,56.38%,52.78%respectively.abnormal karyotype detection rate of different prenatal diagnostic indications were NIPT positive≈parental chromosomal abnormalities>ultrasound abnormalities>serological screening high risk≈age≈adversec pregnancy history.4.Combined karyotype analysis,chromosomal microarray analysis and fluorescence in situ hybridization were used to identify the source and nature of anomalous fragments in 11 pregnant women.The marker chromosomes were from X,Y,2,12,18 chromosomes,and unclear abnormal structure chromosomes were related with X,Y,1,3,4,8,10,13 chromosomes,with ignificance pathogenic variation.Conclusion1.Karyotype analysis of pregnant women with prenatal diagnosis indications can find out the number and structural abnormality of chromosomes.It is a classic prenatal diagnosis method with high clinical value.2.Old age and high-risk of serological screening are the main indications for prenatal diagnosis.The number of prenatal diagnosis indications of pregnant women has a certain correlation with fetal chromosomal abnormalities.The more pregnant women have prenatal diagnosis indications,the higher the risk of fetal chromosomal abnormalities.3.Among the prenatal diagnosis indications,NIPT-positive,parental chromosomal abnormalities have the highest correlation with fetal chromosomal abnormalities.Ultrasound screening plays an important role in prenatal diagnosis.In particular,ultrasound softening NT thickening is of great value for the screening of trisomy 21.4.Combining application of karyotype analysis,fluorescence in situ hybridization,chromosome microarray analysis technology can accurately confirm the chromosome origin and nature of marker chromosomes and unclear structural abnormalities,and provide evidence for clinical diagnosis and treatment. |
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