Meiotic defects in a man with non-obstructive azoospermia: case report.

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. The aim of this study was to determine whether some cases of infertility are associated with decreased meiotic recombination. Analysis of the early stages of meiosis was performed in a 33-year-old man with non-obstructive azoospermia. Newly developed immunocytogenetic techniques were used to identify the synaptonemal complex (SC) in various stages of prophase. Antibodies to meiotic proteins identified the SC (SYN1/SCP3), the centromere (CREST) and recombination sites (MLH1). Only 36 meiotic spreads were recovered from the infertile man, compared with hundreds available from controls. One-third of the cells were in zygotene compared with 4% in controls, demonstrating an inability of bivalents to synapse and progress to pachytene. The infertile man had a greatly reduced frequency of recombination, with a mean of only 32.7 MLH1 foci/cell (range 1-60) compared with 46.0 (range 21-62) in control donors. A high proportion of cells (73%) contained at least one autosomal bivalent with zero MLH1 foci, compared with only 4.5% in control donors. Discontinuities in the SC were also more prevalent (68% of cells versus 26% in controls). This is the first demonstration of dramatic pachytene-stage abnormalities in an infertile man using these powerful new immunocytogenetic techniques.