Cytogenetics and male infertility

Infertile men have an increased frequency of aneuploid sperm. We have determined that decreased recombination is associated with the production of aneuploid sperm in humans. We sought to determine if some cases of infertility are associated with decreased meiotic recombination. Analysis of the early stages of meiosis was performed in 62 men: 29 with nonobstructive azoospermia (NOA), 6 men with obstructive azoospermia (OA), and 27 men with normal spermatogenesis. The mean frequency of recombination was 42.7 for men with NOA and 46.9 for men with OA, both significantly reduced compared to controls 48.5. The percentage of cells with unsynapsed regions was 24.0% in men with NOA, 9.8% in OA, and 15.5% in controls. The mean percentage of cells containing bivalents with no recombination foci was 29.3 in men with NOA, 9.0 in the OA group, and 5.0 in controls. A significant number of men with NOA have abnormalities in chromosome synapsis, a decreased frequency of recombination, and an increased frequency of chromosomes with no recombination foci. These meiotic abnormalities could lead to meiotic arrest or an increased frequency of aneuploid sperm.