Androgen Receptor Gene CAG Repeat Polymorphism and Effect of Testosterone Therapy in Hypogonadal Men in Korea

Abstract

Background: As the number of CAG repeats in the androgen receptor (AR) gene increases, transcriptional activities decrease and the effects of testosterone decline. In this study, we evaluated the importance of the CAG repeat polymorphism in regard to the effect/safety of testosterone therapy in hypogonadal Korean men. Methods: The number of CAG repeats was determined in 42 hypogonadal men who underwent testosterone therapy for more than 24 months between December 1999 and August 2007. Body mass index, lean body mass, body fat, bone mineral density, type I collagen N-telopeptide (NTx), osteocalcin, lipid profile, hematocrit and PSA levels prior to and after 24 months of testosterone therapy were identified in our medical record review. Results: Twenty-four months of testosterone therapy increased lean body mass, hematocrit, and PSA levels and reduced body fat, NTx, and HDL cholesterol levels. The mean number of CAG repeats in the AR gene was 23 ± 3 (range, 15-29) in hypogonadal Korean men. The number of CAG repeats was not found to be associated with changes in lean body mass, body fat, NTx, HDL cholesterol, hematocrit, or PSA levels during testosterone therapy. Conclusions: No association between the number of CAG repeats in the AR gene and the effect/safety of testosterone therapy was detected in hypogonadal Korean men. (Endocrinol Metab 26:225-231, 2011)

Androgen Receptor CAG Repeat Length as a Risk Factor of Late-Onset Hypogonadism in a Korean Male Population

“…The effect of testosterone is mediated through the androgen receptor (AR), the gene for which is located on Xq11-12 and contains 8 exons. 10 The AR gene contains a repeated nucleotide sequence region, [CAG]nCAA (known as the CAG repeat polymorphism and denoted as [CAG]n), which codes for a polyglutamine tract in the N-terminal transactivation domain of exon 1. 11 …”

Positive Correlation between Androgen Receptor CAG Repeat Length and Metabolic Syndrome in a Korean Male Population

“…The mean number of CAG repeats in the present study was 22.3±4.7, which is slightly higher than that in Caucasians [ 15 ]. The only previous study on AR CAG repeat length in Korean men determined the mean number repeats to be 23; however, that study assessed only 42 hypogonadal men [ 16 ]. Therefore, our study is meaningful in that it presents the mean number of AR CAG repeats of a larger group of Korean male patients.…”