Evaluation of optical genome mapping for detecting chromosomal translocation in clinical cytogenetics.

Background: Balanced reciprocal translocation is one of the most common chromosomal abnormalities in humans that may lead to infertility, recurrent pregnancy loss, or having children with physical or mental abnormalities. Karyotyping and FISH are traditional detection approaches with a low resolution. Bionano optical genome mapping (OGM) developed in recent years can be used to analyze chromosomal abnormalities at a higher resolution, providing the possibility of more in-depth analyses of balanced chromosome translocations.

Methods: To evaluate the feasibility of OGM to detect chromosome balanced translocations, 10 genetic outpatients were collected and detected simultaneously by karyotype analysis, FISH, CNV-seq, and Bionano OGM in this study.

Results: The results showed that the karyotypes of the patients were detected by karyotype analysis, FISH, and Bionano OGM, but one patient with karyotype t(Y,19) was not correctly detected by OGM. There were not find any chromosome abnormality by CNV-seq. More importantly, OGM allowed the location of the mutation to the gene level, which is important for aiding diagnoses, compared to karyotype analysis, and FISH.

Conclusions: This study shows that OGM can be a high adjunctive diagnostic method for detecting balanced chromosome translocations, but the accuracy and precision of OGM detecting mutations need to be gradually improved in telomere and centromere regions.