CAG repeat polymorphism in androgen receptor gene is not directly associated with polycystic ovary syndrome but influences serum testosterone levels

• Published in: The Journal of steroid biochemistry and molecular biology Vol. 128; no. 3-5; pp. 107 - 112
• Main Authors: Skrgatic, L., Baldani, D. Pavicic, Cerne, J.Z., Ferk, P., Gersak, K.
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01.02.2012
• Subjects: Acne; Adult; Age; Age Factors; Androgen receptor; Androgen receptors; Androgens; Body Mass Index; CAG repeat polymorphism; Codons; Croatia; Exons; Fasting; Female; Gene Frequency; Gene polymorphism; Genetic Association Studies; Genotyping; Glucose; Hip; Hirsutism; Humans; Hyperandrogenism; Insulin; Insulin Resistance; Models, Genetic; Overweight - complications; Polycystic ovary syndrome; Polycystic Ovary Syndrome - blood; Polycystic Ovary Syndrome - complications; Polycystic Ovary Syndrome - genetics; Polycystic Ovary Syndrome - physiopathology; Polyglutamine; Polymorphism, Genetic; Receptors, Androgen - chemistry; Receptors, Androgen - genetics; Regression analysis; Testosterone; Testosterone - blood; Trinucleotide Repeats; Young Adult; Croatia; Polycystic ovary syndrome; Androgen receptor; CAG repeat polymorphism
• ISSN: 0960-0760; 1879-1220
• DOI: 10.1016/j.jsbmb.2011.11.006

► AR gene CAG repeat length polymorphism in Croatian women with PCOS was studied. ► Polymorphism was found to be equally distributed between PCOS and healthy controls. ► Polymorphism positively correlates with total testosterone levels in PCOS group. ► CAG repeat polymorphism is not associated with hirsutism and acne status. ► Serum androgen levels are not significant predictors of hirsutism and acne status. Hyperandrogenemia has been the most consistent feature of polycystic ovary syndrome (PCOS). Androgens exert their effects through androgen receptors (ARs). The expansion of the codon CAG trinucleotide repeat polymorphism in exon 1 of the AR gene represents a type of genetic alteration associated with changes in the AR gene function. The purpose of this study was to establish a possible association of the AR gene CAG repeat length polymorphism with PCOS, and its influence on clinical and biochemical androgen traits. Two hundred and fourteen Croatian women with PCOS and 209 healthy control women of reproductive age were enrolled. Phenotypic hyperandrogenism, BMI and waist to hip ratio were recorded. Hormonal profiles, fasting insulin and glucose levels were measured on cycle days 3–5. Genotyping of the CAG repeat polymorphism in the AR gene was performed. We found no significant difference in the mean CAG repeat number between the PCOS patients and controls (22.1±3.4 vs. 21.9±3.2, P=0.286). There was a positive correlation between the CAG repeat length and total testosterone (TT) in the PCOS group (R=0.225, P=0.015). A multiple linear regression model using mean CAG repeat length, BMI, age and HOMA-IR as predictors explained 8.5% (adjusted R2) of the variability in serum TT levels. In this model the CAG repeat polymorphism was found to be a significant predictor of serum TT levels in PCOS patients (P=0.015). The logistic regression analysis revealed that the CAG repeat length is not a significant predictor of hirsutism and acne status (P=0.921 and P=0.437, respectively). The model was adjusted for serum TT, free testosterone, androstendione and DHEAS levels as independent variables, which were also not found to be significant predictors of hirsutism (P=0.687, P=0.194, P=0.675 and P=0.938, respectively) or acne status (P=0.594, P=0.095, P=0.290 and P=0.151, respectively). In conclusion, the AR CAG repeat polymorphism is not a major determinant of PCOS in the Croatian population, but it is a predictor of serum TT level variability in women with PCOS.