Genetic disorders and spermatogenesis

Abstract

Male infertility affects one man in twenty and a genetic basis seems likely inat least 30% of those men. Genetic regulation of fertility involves theinter-related processes of testicular development, spermatogenesis (involvinggerm cell mitosis, meiosis and spermatid maturation), and their endocrine andparacrine regulation. In regard to spermatogenesis, particular attention hasbeen given to the Yq11 region, where some spermatogenesis genes(‘azoospermia factors’) appear to be located. Several candidategenes have been identified but have not been shown to have a defined oressential role in spermatogenesis. Microdeletions of Yq11 are found in~15% of azoospermic or severely oligospermic men. The complexity of thegenetic control of male fertility is demonstrated by the evidence for genesinvolved in spermatogenesis and sexual differentiation on the X chromosome andautosomes. Better understanding of the genetic regulation of normalspermatogenesis will provide new probes for clinical studies; however, atpresent the majority of spermatogenic failure remains without an identifiedgenetic linkage. The advent of intracytoplasmic sperm injection permitsfertility in many previously sterile men and presents the possibility of theirtransmission of infertility; appropriate counselling is required.