Androgen Receptor Polymorphisms (CAG Repeat Lengths) in Androgenetic Alopecia, Hirsutism, and Acne

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Abstract
Background: The androgen receptor (AR) is a structurally conserved member of the nuclear receptor superfamily. The amino-terminal domain is required for transcriptional activation and contains a region of polyglutamine encoded by CAG trinucleotide repeats. In humans, the number of CAG repeats is polymorphic. Expansion of CAG repeats in the AR has clinical implications for human disease. Objective: Androgens influence androgenetic alopecia (AGA), hirsutism, and acne; the polymorphisms in CAG repeat length may affect the clinical course of patients with these cutaneous disorders. The purpose of this study is to test for an association between these disorders and CAG repeat length. Methods: We analyzed normal lymphocyte genomic DNA from a total of 48 men and 60 women. The CAG repeat region of the AR was amplified by polymerase drain reaction (PCR) and the products were sized on polyacrylamide gels. Results: In normal men and women controls, a range of 12 to 29 trinucleotide repeats was found, with men having 22 ± 4 (M ± SD), women 21 ± 3. Men with AGA had 19 ± 3, whereas women with AGA had 17 ± 3. Men with acne had 21 ± 3, whereas women had 20 ± 3; men with AGA and acne had 18 ± 4; and women with hirsutism had 16 ± 3. Women with a combination of at least two disorders also had 16 ± 3 trinucleotide repeats. Conclusion: Shorter CAG-repeat lengths may be associated with the development of androgen-mediated skin disorders in men and women. These data suggest that CAG-repeat length in AR may affect androgen mediated gene expression in hair follicles and sebaceous glands in men and women with these androgenic skin disorders.