sentences:  Female and male "MLH1"(-/-) mutant mice are infertile, and sterility is associated with a reduced level of chiasmata.During spermatogenesis in "MLH1"(-/-) mutant mice chromosomes often separate prematurely and there is frequent arrest in the first division of meiosis.In humans, a common variant of the "MLH1" gene is associated with increased risk of sperm damage and male infertility.