Karyotype Analysis and Chromosomal Microarray Analysis in 568 Couples with Balanced Translocation for Prenatal...

Chromosomal balanced translocation is a prevalent structural chromosomal abnormality. Carriers typically exhibit no phenotypic differences, as the genetic material remains unchanged. However, during germ cell meiosis, unbalanced gametes may be produced, leading to genetic effects in offspring and potentially resulting in adverse outcomes. This study aims to explore the prenatal diagnostic value of combining chromosome karyotype analysis with chromosomal microarray analysis (CMA) for carriers of balanced chromosomal translocations, and to provide a reference for clinical genetic counselling.

A total of 568 pregnant women who underwent prenatal diagnosis at our hospital from January 2018 to December 2023, in which one of the spouses was a balanced translocation carrier, were included. Amniocentesis was performed for karyotype analysis and CMA to detect abnormal chromosomes and assess the risk of adverse pregnancy outcomes in the fetus.

Among the 568 examinees, karyotype analysis identified 236 cases of abnormal fetuses (41.55%), whereas CMA identified 200 cases (35.21%). The combination of both methods detected a total of 265 cases of abnormal fetuses (46.65%). Karyotype analysis identified 163 cases (28.70%) as high risk for adverse pregnancy outcomes, whereas CMA and the combined use of both methods identified 183 cases (32.22%) as high risk. These differences were attributed to each method's adaptability and limitations. Follow-up revealed a 100% rate of adverse outcomes among those at high and moderate risk.

Couples with balanced chromosomal translocations face an increased risk of adverse pregnancy outcomes. While karyotyping is effective in identifying diverse chromosomal abnormalities, its ability to detect minor fragments is limited. Conversely, CMA excels at identifying chromosomal abnormalities with small fragments but struggles with detecting balanced structural variations. The concurrent application of both technologies enhances the precision of diagnosing the risk of adverse pregnancy outcomes.