Summary It is apparent that male infertility is associated with mild to moderate expansion of the CAG trinucleotide repeat in the transactivation domain of the androgen receptor gene. Introduction Human infertility can occur as a consequence of historical mutations where the cause of infertility may be an accumulation of defects that finally manifest under the appropriate conditions or be denovo mutations that appear in the genome of the individual without an inheritance from the parental somatic genotype. These latter mutations may occur in the germ cells of parents without being expressed in the remainder of their cells and tissues.
Inherited infertility can be either male or female related.
Congenital absence of the vas is closely related to cystic fibrosis and may be due to the same mutation. Of some interest are the mutations found in the androgen receptor gene that is a nuclear tran scription factor that when activated will induce androgen-regulated genes required for spermatogenesis and sexual differentiation. Mutations will cause androgen insensitivity syndrome and partial syndromes involving female phenotypes and ambiguous genitalia. Men with severe infertility will usually not transmit gene mutations because they are unlikely to have children by natural methods of conception. The concern may be increased if these mutations are associated with other pathologies and if the severity of these conditions increases.