GENETIC-DISORDERS AND SPERMATOGENESIS

Male infertility affects one man in twenty and a genetic basis seems l ikely in at least 30% of those men. Genetic regulation of fertility in volves the inter-related processes of testicular development, spermato genesis (involving germ cell mitosis, meiosis and spermatid maturation ), and their endocrine and paracrine regulation. In regard to spermato genesis, particular attention has been given to the Yq11 region, where some spermatogenesis genes ('azoospermia factors') appear to be locat ed. Several candidate genes have been identified but have not been sho wn to have a defined or essential role in spermatogenesis. Microdeleti ons of Yq11 are found in similar to 15% of azoospermic or severely oli gospermic men. The complexity of the genetic control of male fertility is demonstrated by the evidence for genes involved in spermatogenesis and sexual differentiation on the X chromosome and autosomes. Better understanding of the genetic regulation of normal spermatogenesis will provide new probes for clinical studies; however, at present the majo rity of spermatogenic failure remains without an identified genetic li nkage. The advent of intracytoplasmic sperm injection permits fertilit y in many previously sterile men and presents the possibility of their transmission of infertility; appropriate counselling is required.