RESUMEN
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.