Role of karyotyping combined with chromosomal microarray analysis in prenatal diagnosis of balanced translocation or inversion carriers / 中华围产医学杂志

ABSTRACT

Objective:To explore the value of karyotyping and chromosomal microarray analysis (CMA) in the prenatal diagnosis of balanced translocation/inversion carriers.Methods:This was a retrospective study involving 117 balanced translocation/inversion carrier couples. Among them, 90 women had a history of spontaneous abortion(≥2 times), stillbirth, fetal multiple malformations, or giving birth to children with chromosome abnormality disease and the peripheral blood karyotyping and fluorescence in situ hybridization testing confirmed that one partner was balanced translocation/inversion carrier. The present pregnancies of these cases were spontaneous and lasted until 18-25 weeks. The other 27 cases were confirmed by chromosome examination at the present pregnancy after the indication of fetal structural abnormalities by fetal karyotyping due to advanced maternal age and abnormal ultrasound and prenatal screening results. The results of karyotyping and CMA by amniocentesis during 18 to 25 gestational weeks were all summarized and described. Results:The successful rate of both methods was 100.0% (117/117). Unbalanced and balanced translocation/inversion were detected in seven (6.0%) and 39 (33.3%) fetuses by karyotyping, respectively. CMA revealed 14 fetuses with pathogenic copy number variation (CNV) and one with variants of uncertain significance(VUS), with an anomaly detection rate of 12.8% (15/117). Among the 15 cases with CNV, 13 were related to the parental translocation/inversion, one with de novo mutation (22q11.2 microdeletion syndrome), and one Duchenne muscular dystrophy mutation carrier. Based on the results of karyotype and CMA, there were 12 fetuses with unbalanced chromosomal fragments (10.3%), 37 fetuses with balanced translocation/inversion (31.6%), and 68 fetuses with normal chromosomes (58.1%). Conclusions:The combination of karyotyping and CMA can provide more accurate prenatal genetic diagnosis when one of a couple carries balanced chromosomal translocations/inversion.