Cytogenetic alterations in infertile men seeking assisted reproduction: associations with semen quality

Abstract

Male infertility accounts for approximately half of all infertility cases and is often linked to chromosomal abnormalities. While numerical and structural rearrangements are well recognized, the clinical significance of chromosomal polymorphisms remains unclear. To characterize the spectrum of cytogenetic alterations - including polymorphisms, structural rearrangements, and numerical changes - in men presenting with infertility and to assess their incidence on men with semen abnormalities. In this retrospective observational study, peripheral blood samples from 62 patients with detected cytogenetic alterations were collected at Genos Laboratory (Unimed Diagnostic Center) in Bauru, Brazil, between January 2015 and June 2020. Semen analysis reports for these patients were retrieved from the Fertility Clinic in Bauru, Brazil. Following specialist evaluation, a final cohort of 38 men diagnosed with infertility was analyzed. Results: Chromosomal polymorphisms were the most frequent alteration (77.4%), followed by structural rearrangements (17.7%) and numerical changes (4.8%). Among polymorphism carriers, 58% exhibited at least one abnormal semen parameter, most commonly asthenozoospermia (42%), teratozoospermia (38%), and oligozoospermia (33%). The 46,XYqh⁺ variant predominated (50%), with half of these cases demonstrating semen abnormalities. Double polymorphisms (46,XY9qh⁺ and 46,XY22ps⁺; <i>n</i> = 8) were uniformly associated with oligozoospermia and teratozoospermia. Structural alterations - pericentric inversion of chromosome 9 and Robertsonian translocation rob(13;14)(q10q10) - were found in 11 patients; 72% of these also had semen abnormalities. Numerical alterations were rare but associated with abnormal semen parameters in 66% of cases. Chromosomal polymorphisms, though traditionally viewed as benign, were frequently detected in compromised semen quality in this cohort. Structural and numerical rearrangements, while less common, were detected in a higher proportion of abnormal semen parameters. These findings underscore the value of comprehensive cytogenetic screening in the evaluation of male infertility.