The interaction of serum testosterone levels and androgen receptor CAG repeat polymorphism on the risk of erectile dysfunction in aging Taiwanese men

C C Liu; Y C Lee; V F S Tsai; K H Cheng; W J Wu; B Y Bao; C N Huang; H C Yeh; C C Tsai; C J Wang; S P Huang

doi:10.1111/andr.12068

The interaction of serum testosterone levels and androgen receptor CAG repeat polymorphism on the risk of erectile dysfunction in aging Taiwanese men

Andrology. 2015 Sep;3(5):902-8. doi: 10.1111/andr.12068. Epub 2015 Jul 27.

Authors

C C Liu^{1

2

3}, Y C Lee^{1

2}, V F S Tsai⁴, K H Cheng⁵, W J Wu^{1

2

6}, B Y Bao⁷, C N Huang^{1

2}, H C Yeh^{2

8}, C C Tsai⁸, C J Wang^{1

2}, S P Huang^{1

2}

Affiliations

¹ Department of Urology, Kaohsiung Medical University Hospital, Kaohsiung Medical University, Kaohsiung, Taiwan.
² Department of Urology, Faculty of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan.
³ Depratment of Urology, Pingtung Hospital, Ministry of Health and Welfare, Executive Yuan, Pingtung, Taiwan.
⁴ Department of Urology, Ten-Chan General Hospital, Taoyuan, Taiwan.
⁵ Division of Cardiology, Department of Internal Medicine, Kaohsiung Medical University Hospital, Kaohsiung, Taiwan.
⁶ Department of Urology, Kaohsiung Municipal Hsiao-Kang Hospital, Kaohsiung, Taiwan.
⁷ Department of Pharmacy, China Medical University, Taichung, Taiwan.
⁸ Department of Urology, Kaohsiung Municipal Ta-Tung Hospital, Kaohsiung, Taiwan.

PMID: 26216079
DOI: 10.1111/andr.12068

Abstract

Testosterone has been found to play important roles in men's sexual function. However, the effects of testosterone can be modulated by androgen receptor (AR) CAG repeat polymorphism. It could also contribute to the risk of erectile dysfunction (ED). The aim of this study is to evaluate the interaction of serum testosterone levels and AR CAG repeat polymorphism on the risk of ED in aging Taiwanese men. This cross-sectional data of Taiwanese men older than 40 years were collected from a free health screening held between August 2010 and August 2011 in Kaohsiung city, Taiwan. All participants completed a health questionnaires included five-item version of the International Index of Erectile Function (IIEF-5) and the International Prostate Symptoms Score, received a detailed physical examination and provided 20 cm3 whole blood samples for biochemical and genetic evaluation. The IIEF-5 was used to evaluate ED. Serum albumin, total testosterone (TT), and sex hormone-binding globulin levels were measured. Free testosterone level was calculated. AR gene CAG repeat polymorphism was determined by direct sequencing. Finally, 478 men with the mean age of 55.7 ± 4.8 years were included. When TT levels were above 330 ng/dL, the effect of testosterone level on erectile function seemed to reach a plateau and a significantly negative correlation between AR CAG repeat length and the score of IIEF-5 was found (r = -0.119, p = 0.034). After adjusting for other covariates, the longer AR CAG repeat length was still an independent risk factor for ED in subjects with TT above 330 ng/dL (p = 0.006), but not in TT of 330 ng/dL or below. In conclusion, both serum testosterone levels and AR CAG repeat polymorphism can influence erectile function concomitantly. In subjects with normal TT concentration, those with longer AR CAG repeat lengths have a higher risk of developing ED.

Keywords: CAG repeat polymorphism; Testosterone; androgen receptor; erectile dysfunction; hypogonadism.

MeSH terms

Adult
Aged
Aged, 80 and over
Aging
Cross-Sectional Studies
Erectile Dysfunction / blood*
Erectile Dysfunction / epidemiology
Erectile Dysfunction / genetics*
Humans
Male
Middle Aged
Polymorphism, Single Nucleotide
Receptors, Androgen / genetics*
Risk Factors
Serum Albumin / analysis
Sex Hormone-Binding Globulin / metabolism
Surveys and Questionnaires
Taiwan / epidemiology
Testosterone / blood*

Substances

Receptors, Androgen
Serum Albumin
Sex Hormone-Binding Globulin
Testosterone