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Objective:Cytogenetic and molecular genetic analysis was performed on two consecutive antenatal abnormal fetuses and their parents in a family to clarify the copy number variation(CNV) and its mechanism.Methods:The karyotypes of two fetuses and their parents were analyzed by conventional karyotyping techniques, and CNVs of two fetuses and their mother were analyzed by low-coverage whole-genome copy number variation sequencing (CNV-seq) techniques.Results:The amniotic fluid karyotype results of fetus 1 and 2 were 46, XN, der(4)t(4;10)(q35;p13). The mother′s peripheral blood karyotype result was 46, XX, t(4;10)(q35;p13), and the father′s karyotype was normal. The CNV-seq results of fetus 1 and 2 were seq[hg19]6q22.31(122740000-125440000)X1; 10p15.3p13(120000-17260000)X3, suggesting that there was a heterozygous deletion of about 2 700 000 bp in fetal 6q22.31 and a duplication of about 17 140 000 bp in fetal 10p15.3p13. The CNV-seq result of their mother was seq[hg19]6q22.31(122740000-125440000)X1, suggesting that there was a heterozygous deletion of about 2 700 000 bp in 6q22.31. The pregnant woman and her family chose to terminate the pregnancy after genetic consulting.Conclusion:The combined application of karyotyping and CNV-Seq is significantly beneficial to detecting microdeletions or microduplications of fetal chromosomes and effectively preventing the birth of defective children.
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Objective:To explore the clinical application value and accuracy of cell-free fetal DNA (cff-DNA) technique in prenatal screening.Methods:The results of quantitative fluorescent PCR (QF-PCR) and karyotype of amniotic fluid cells were analyzed retrospectively in 2 398 monocyesis pregnant women who had been amniocentesis at the First Affiliated Hospital of Zhengzhou University from May 2013 to December 2019, and the results of 359 cases who had been examined by single-nucleotide polymorphism array (SNP array).Results:Cff-DNA test of 2, 398 cases indicated 987 cases of trisomy 21, 351 cases of trisomy 18, 135 cases of trisomy 13, 566 cases of sex chromosome abnormality, and 359 cases of other chromosome abnormality. Chromosome karyotype analysis detected 826 cases of trisomy 21, 213 cases of trisomy 18, 17 cases of trisomy 13, 221 cases of sex chromosome abnormality, and 26 cases of other chromosome abnormality. The detection rate were 83.69% (826/987), 60.68% (213/351), 12.59% (17/135), 39.04% (221/566) and 7.24% (26/359), respectively. QF-PCR detected 1 046 cases of trisomy and 188 cases of sex chromosomes abnormality, and the detection rate was 99.05% (1 046/1 056) and 85.07% (188/221), respectively. Compared with the abnormal number detected by chromosome karyotype analysis, 10 cases of trisomeric chimerism and 24 cases of sex chromosome were missed by QF-PCR. Among the 359 other chromosomal abnormalities detected by SNP array, 64 cases were consistent with the results of cff-DNA, and the detection rate was 17.83% (64/359), which was 10.59% higher than the karyotype result.Conclusions:Karyotype analysis is the gold standard for diagnosing chromosomal abnormalities. QF-PCR could diagnose common chromosome aneuploidy rapidly and accurately, and it could be used as an auxiliary detection technique for karyotype analysis. The incidence of sex chromosome chimerism is high, so missed diagnosis should be warned. SNP array could be given priority to verify chromosome microdeletion or microduplication detected by cff-DNA.
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Objective To investigate the value of prenatal diagnosis in identifying the etiology and predicting the prognosis of fetal pleural effusion (FPE).Methods Forty-two cases of FPE were recruited in this study from January 2012 to September 2016.Ultrasound scan and genetic tests were performed on all fetuses.Seven fetuses with severe FPE were given pleurocentesis.Pregnancy outcomes of all the fetuses were followed up.Results FPE was commonly accompanied with other abnormalities,such as ascites,hydrops,hydramnion,hygroma colli,abnormal posturing,joint contractures,arrhythmia and micromandible.Chromosomal abnormality was detected in 11 fetuses (26.2％),of which ten were further confirmed by karyotype analysis,including six with 45,X,three trisomy 21 and one trisomy 18,and one was detected with a 9.83 Mb uniparental disomy (UPD) located at 12q24.21q24.31 by gene chip.One fetus was diagnosed with--SEA/--SEA thalassemia.All of the 12 families decided to terminate the pregnancies after genetic counseling.Among the other 30 fetuses,seven with severe FPE and normal karyotype underwent pleurocentesis.Five of the seven cases were with favorable outcomes,one with progressive hydrops was aborted and one neonate with severe hydrops died after birth.Spontaneous regression of FPE with good outcome was found in two cases.Parents of the other 21 fetuses chose to terminate the pregnancies.Conclusions Prenatal diagnosis is important to identify the etiology and predict the outcome of FPE.Chromosomal abnormality is a relatively common cause of FPE,and 45,X and trisomy 21 are the most common abnormalities.Intrauterine intervention is beneficial for FPE without chromosomal or other definite genetic abnormalities.Genetic test may be of great value for pregnant counseling.