Chromosomal Roadblocks in Male Fertility: Mechanisms, Risk Factors and Syndromes.

Male infertility affects nearly 15% of couples worldwide, with chromosomal abnormalities representing a major underlying cause. This review explores how numerical and structural chromosomal anomalies, along with environmental exposures, lifestyle factors, and age-related genetic changes, disrupt spermatogenesis and contribute to infertility. It synthesizes findings from cytogenetic, molecular, and clinical studies, with particular focus on mechanisms such as meiotic nondisjunction, spindle assembly checkpoint dysfunction, and alterations in cohesin and synaptonemal complex proteins. Chromosomal abnormalities, both numerical and structural, emerge as key contributors to male infertility by impairing chromosomal segregation and recombination, often leading to azoospermia or oligospermia. Meiotic checkpoint failures and recombination errors further exacerbate the production of aneuploid sperm. Environmental toxins, oxidative stress, and poor nutrition disrupt hormonal balance and chromatin integrity, while advancing paternal age is associated with increased sperm aneuploidy and impaired meiotic control, with implications for assisted reproduction. Specific syndromes, including AZF deletions, Kallmann syndrome, and 46,XX testicular DSD, exemplify the direct genetic impact on male fertility. Overall, chromosomal abnormalities are central to the pathophysiology of male infertility, arising from intrinsic meiotic errors as well as extrinsic environmental and lifestyle factors. Integrating cytogenetic diagnostics, genetic counseling, and lifestyle interventions is essential for comprehensive fertility assessment and management. Further research into molecular biomarkers and targeted therapies could enhance diagnosis, improve treatment strategies, and lead to better reproductive outcomes.