Objective To investigate the application value of a combined approach,including chromosome karyotype analysis,bacterial artificial chromosome on beads(BoBs),copy number variations(CNV),and azoospermia factor(AZF)on the Y chromo-some,for identifying chromosomal abnormalities in amniotic fluid samples from pregnant women.Methods From July 2021 to De-cember 2022,507 pregnant women who met the indications of prenatal diagnosis were selected from the prenatal diagnosis center of the First Affiliated Hospital of Wannan Medical College(Yijishan Hospital).Amniotic fluid of 16-25 w of pregnancy was extracted,and cell culture chromosome karyotype analysis was performed,and DNA was extracted for BoBs detection.CNV verification was per-formed in 1 case of trisomy 21 syndrome and 1 case of labeled chromosome,and AZF microdeletion verification was performed in 2 ca-ses of Y chromosome.Results Among the 507 cases,the highest indication for amniotic fluid puncture was due to a high-risk of Down's syndrome,accounting for 39.1%(198/507);however,the majority of abnormal cases were detected in the non-invasive prenatal testing high-risk group,which only accounted for 14%of all pregnant women,with abnormalities found by both karyotype a-nalysis(23/57)and BoBs(21/44).Abnormal results were found in59(11.6%)of 507 amniotic fluid samples.Out of these ca-ses,57 cases were abnormal by chromosome karyotype analysis(11.2%),including 26 cases with abnormal autosomal numbers(5.1%),14 cases with autosomal structural abnormalities(2.8%),13 cases with abnormal sex chromosome numbers(2.6%),and 4 cases with structural abnormalities of sex chromosomes(0.7%).BoBs detected 44 abnormal cases(8.7%),including 26 ca-ses with abnormal autosomal numbers(5.1%),14 cases with abnormal sex chromosome numbers(2.8%),2 cases with partial de-letions of sex chromosomes(0.4%),and 2 cases with 46,XN,22q11 duplication(0.4%).The coincidence rates of abnormal au-tosomal numbers and sex chromosomes numbers between BoBs and karyotype analysis were100.0%and99.8%,respectively.How-ever,1 case of 46,X,del(Y)(q11)was misjudged as 45,XO and 1 case of 47,XN,+mar[50]/46,XN[10]was mis-judged as 46,XN by BoBs.Chromosome structural abnormalities were not within the detection range of BoBs.One case of pathogenic copy number variation and one case of unknown copy number variation were verified by CNV.Two cases of Y chromosomes were posi-tive for SRY+ and AZFb+c deletion confirmed by AZF.Conclusion chromosome karyotype analysis can detect abnormal chromosome number and structure in amniotic fluid,but may not be able to detect marker chromosomes of unknown origin or microdeletions or mi-crorepeats smaller than 10 Mb.BoBs are advantageous in detecting chromosome numbers and microdeletions or microrepeats,and can also indicate the loss of sex chromosome fragment deletion.However,the misjudgment of sex chromosomes should be taken into con-sideration,and BoBs cannot detect autosomal structural abnormalities.CNV has advantages in detecting genome-wide microdeletions or microrepetitions,and AZF can verify Y chromosomes.A combination of these techniques can provide a multidirectional diagnosis of chromosomal abnormalities in amniotic fluid.
chromosome karytype analysisBoBsCNVdetection of AZF microdeletion on Y chromosomeamniotic fluid
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