Clinical and molecular aspects of androgen receptor defects

The androgen receptor (AR) is a ligand-dependent transcription factor invol ved in various biological processes such as sex differentiation, sexual mat uration and spermatogenesis. Disorders of AR function cause a wide spectrum of androgen insensitivity syndromes. The phenotypes vary from women with f emale external genitalia through patients with genital ambiguity to men wit h normal male genitalia but infertile. The CAG repeat in exon A is importan t for transactivation function of the AR and consequently for many androgen -dependent processes. Expansion of this repeat is the cause of the X-linked spinal and bulbar muscular atrophy (SBMA, Kennedy's disease). Mutations of the AR gene occur commonly in prostate cancers and are significant for pro gnosis of the disease.