The accuracy and real resolution of karyotyping technique in detecting chromosomal aberrations identified by molecular genetic methods.

Although karyotyping technology has been implemented in genetic diagnosis for a long time, the comprehensive understanding of this technology is still limited. The aim of this study was to investigate the accuracy and resolution of karyotyping method in detecting chromosomal abnormalities by molecular genetic method. In this study, we conducted a retrospective analysis of embryonic molecular karyotypes and peripheral blood cytogenetic karyotypes from patients with balanced chromosomal rearrangements undergoing preimplantation genetic testing at our reproductive center. Blood karyotyping was performed using routine G-banding at the 400-band resolution by two well-trained technicians. The embryonic molecular karyotypes were detected using either high-throughput sequencing or single nucleotide polymorphism microarray method. We compared the breakpoint locations, determined by unbalanced rearrangements, in the embryonic molecular karyotypes with the corresponding rearranged chromosome bands in the peripheral blood karyotypes. A total of 508 cases were enrolled and 2078 embryos were detected, 404 cases were analyzed finally. We found that only 39.32% (289/735) of embryonic molecular breakpoints were located within the rearranged bands identified by peripheral blood karyotyping, while the remaining 60.68% (446/735) fell outside these regions. Our results showed only 73 cases exhibited accurate karyotyping results, indicating an accuracy rate of 18.07%. Furthermore, the average resolution of karyotyping technique was found to be approximately 9.01 megabases (Mb) pairs. These findings provide profound insight into the accuracy and resolution of karyotyping techniques, which can contribute to more precise genetic counseling.