The role of androgen receptor CAG repeat polymorphism in androgen excess disorder and idiopathic hirsutism

Purpose The study aimed to investigate whether repeat number in the androgen receptor (AR) gene has any contribution to phenotypes of the disease of androgen excess (polycystic ovary syndrome (PCOS), idiopathic hyperandrogenemia (IHA) and idiopathic hirsutism (IH) in a cohort of Turkish women. Methods Three hundred and fifty-four voluntary premenopausal women (172 healthy controls and 182 patients with androgen excess disorders and idiopathic hirsutism) 18-45 years of age seen at an outpatient endocrine clinic at Erciyes University Hospital between January 2013 and December 2014 were included. All volunteers have undergone physical examination and biochemical evaluation. The polymorphic (CAG)n repeat of the human AR was determined by fragment analyses. Results Detailed clinical analyses of the patients ended up with 137 PCOS, 24 IHA, and 21 IH. Pairwise comparisons revealed the CAG repeat number differences between the PCOS and controls (p = 0.005) and IH and controls (p = 0.020). Women with CAG repeat length <= 17 had a significantly increased twofold risk for PCOS than those women with > 17 CAG repeats OR: 2.0 (95% CI 1.2-3.3,p = 0.005). Women with CAG repeat length <= 17 had a significantly increased threefold risk for IH than those women with > 17 CAG repeats OR: 2.9 (95% CI 1.2-7.3,p = 0.020). When correlation analysis was performed, a weak negative correlation was detected between the short allele and FGS score (r = - 0.131,p = 0.013) and a positive relationship between total testosterone and longer allele in the IHA group (r = 0.425,p = 0.039). Median repeat length of the shorter allele between oligomenorrhea and woman with normal menstrual cycle was found to be statistically significant (p = 0.017). Conclusion This study indicated that the risk of PCOS and IH is associated with the inheritance of ARs with shorter CAG repeats.