Androgen receptor (AR) gene has been extensively studied in diverse clinical conditions. In addition to the point mutations, trinucleotide repeat (CAG and GGN) length polymorphisms have been an additional subject of interest and controversy among geneticists. The polymorphic variations in triplet repeats have been associated with a number of disorders, but at the same time contradictory findings have also been reported. Further, studies on the same disorder in different populations have generated different results. Therefore, combined analysis or review of the published studies has been of much value to extract information on the significance of variations in the gene in various clinical conditions. AR genetics has been reviewed extensively but until now review articles have focused on individual clinical categories such as androgen insensitivity, male infertility, prostate cancer, and so on. We have made the first effort to review most the aspects of AR genetics. The impact of androgens in various disorders and polymorphic variations in the AR gene is the main focus of this review. Additionally, the correlations observed in various studies have been discussed in the light of in vitro evidences available for the effect of AR gene variations on the action of androgens.
Androgen-Insensitivity Syndrome ; genetics ; physiopathology ; Bone Diseases, Metabolic ; genetics ; physiopathology ; Breast Neoplasms ; genetics ; physiopathology ; Cognition Disorders ; genetics ; physiopathology ; Digestive System Diseases ; genetics ; physiopathology ; Female ; Genital Neoplasms, Female ; genetics ; physiopathology ; Genital Neoplasms, Male ; genetics ; physiopathology ; Humans ; Infertility, Male ; genetics ; Male ; Muscular Atrophy, Spinal ; genetics ; physiopathology ; Phenotype ; Point Mutation ; Polycystic Ovary Syndrome ; genetics ; physiopathology ; Polymorphism, Genetic ; Pre-Eclampsia ; genetics ; physiopathology ; Pregnancy ; Receptors, Androgen ; genetics ; physiology ; Schizophrenia ; genetics ; physiopathology ; Testosterone ; deficiency ; Trinucleotide Repeats

AIMTo investigate the role of CAG and GGN repeats as genetic background affecting androgen insensitivity syndrome (AIS) phenotype.

METHODSWe analyzed lengths of androgen receptor (AR)-CAG and GGN repeats in 69 AIS cases, along with 136 unrelated normal male individuals. The lengths of repeats were analyzed using polymerase chain reaction (PCR) amplification followed by allelic genotyping to determine allele length.

RESULTSOur study revealed significantly shorter mean lengths of CAG repeats in patients (mean 18.25 repeats, range 14-26 repeats) in comparison to the controls (mean 22.57 repeats, range 12-39 repeats) (two-tailed P < 0.0001). GGN repeats, however, did not differ significantly between patients (mean 21.48 repeats) and controls (mean 21.21 repeats) (two-tailed P = 0.474). Among patients' groups, the mean number of CAG repeats in partial androgen insensitivity cases (mean 15.83 repeats) was significantly less than in complete androgen insensitivity cases (mean 19.46 repeats) (two-tailed P < 0.0001).

CONCLUSIONThe findings suggest that shorter lengths of repeats in the AR gene might act as low penetrance genetic background in varying manifestation of androgen insensitivity.

Androgen-Insensitivity Syndrome ; genetics ; DNA ; genetics ; Follicle Stimulating Hormone ; blood ; Genetic Predisposition to Disease ; Humans ; Luteinizing Hormone ; blood ; Male ; Phenotype ; Receptors, Androgen ; genetics ; Regression Analysis ; Testosterone ; blood ; Trinucleotide Repeats ; genetics