Effective detection of 148 cases chromosomal mosaicism by karyotyping, chromosomal microarray analysis and QF-PCR in 32,967 prenatal diagnoses.

Abstract

Background: Detection of mosaicism has always been difficult in prenatal diagnosis, which is to assess the value of karyotyping combined with three different molecular genetic tests for prenatal diagnosis. Retrospective review of chromosomal mosaicism (CM) was conducted in 32,967 pregnant women from January 2015 to December 2022.

Methods: A total of 148 fetuses diagnosed with chromosomal mosaicism by karyotyping with copy number variant sequencing (CNV-seq)/ chromosomal microarray analysis (CMA) and quantitative fluorescent polymerase chain reaction (QF-PCR) were selected, and the results from three the methods were compared and further analyzed. The χ2 test for multiple group rates was for the 5 clinical prenatal diagnostic indication groups was used to do multiple comparison tests for statistical analysis. Inconsistent results between methods were identified and further analyzed.

Results: A total of 148 CM cases was detected (0.45%, 148/32967), of which karyotyping was detected in combination with CMA in 73 cases (73/85), with CNV-seq in 5 cases (5/11), and with QF-PCR in 35 cases (35/52) and the mosaic conformity rates of the three methods compared with karyotyping were 85.9% (CMA), 67.3% (QF-PCR), and 45.5% (CNV-seq), respectively. There were 49 cases of autosomal mosaicism (49/148, 33.1%) and 99 cases of sex CM (99/148, 66.9%). There were 9 cases of small supernumerary marker chromosome (sSMC)with CMA detection clarified the origin of chromosome fragments. The non-invasive prenatal testing (NIPT) group and the ultrasound abnormality group had the highest detection rates, accounting for 35.1% and 22.3%.

Conclusions: In chromosomal mosaicism, there are inconsistent results between different detection methods. Therefore, karyotyping combined with CMA/CNV-seq and FISH methods significantly improves the detection rate of chromosomal mosaicism and also confirms experimental data in the literature, which is of great value for prenatal diagnosis.