Department of Endocrinology Biochemistry, Odense University Hospital, Sdr Boulevard, 5000 Odense C, Denmark.
Eur J Endocrinol. 2010 Apr;162(4):795-804. doi: 10.1530/EJE-09-0763. Epub 2010 Feb 4.
The number of CAG repeats (CAG(n)) within the CAG repeat polymorphism of the androgen receptor gene correlates inversely with the transactivation of the receptor.
To examine the impact of CAG(n) on muscle, fat distribution, and circulating androgen levels. Design, settings and participants Population-based, cross-sectional study of 783 Danish men aged 20-29 years.
Genotyping was performed in 767 men. Areas of thigh and lower trunk muscle (muscle(thigh) and muscle(lower trunk)), subcutaneous adipose tissues (SAT(thigh) and SAT(lower trunk)), and deep adipose tissues (i.m. and visceral) were measured in 393 men by magnetic resonance imaging (MRI). Lean body mass (LBM) and fat mass (FM) were measured in all men by whole body dual-energy X-ray absorptiometry (DEXA). The absolute areas acquired by MRI were the main outcomes. The absolute DEXA measurements and relative assessments of both modalities were considered as the secondary outcomes. Results CAG(n) (range: 10-32) correlated inversely with absolute muscle(thigh) (r=-0.108), absolute muscle(lower trunk) (r=-0.132), relative muscle(thigh) (r=-0.128), relative muscle(lower trunk) (r=-0.126), relative LBM(lower extremity) (r=-0.108), and relative LBM(total) (r=-0.082), and positively with relative SAT(thigh) (r=0.137), relative SAT(lower trunk) (r=0.188), relative FM(lower extremity) (r=0.107), and relative FM(total) (r=0.082). These relationships remained significant, controlling for physical activity, smoking, chronic disease, and age. CAG(n) did not correlate with any circulating androgen.
The CAG repeat polymorphism affects body composition in young men: absolute muscle(thigh) and absolute muscle(lower trunk) increase as CAG(n) decreases. Expressed relatively, muscle areas and LBM increase, while SAT and FM decrease as CAG(n) decreases. The polymorphism does not affect deep adipose tissues or circulating androgen levels in young men.
雄激素受体基因的 CAG 重复多态性中的 CAG(n) 重复次数与受体的反式激活呈负相关。
研究 CAG(n) 对肌肉、脂肪分布和循环雄激素水平的影响。
设计、地点和参与者：这是一项基于人群的 783 名丹麦 20-29 岁男性的横断面研究。
对 767 名男性进行基因分型。393 名男性通过磁共振成像（MRI）测量大腿和下躯干的肌肉（大腿肌肉和下躯干肌肉）、皮下脂肪组织（大腿 SAT 和下躯干 SAT）和深部脂肪组织（i.m. 和内脏）。所有男性均通过全身双能 X 射线吸收法（DEXA）测量瘦体重（LBM）和体脂量（FM）。MRI 获得的绝对面积是主要结局。DEXA 的绝对测量值和两种模式的相对评估被视为次要结局。
CAG(n)（范围：10-32）与绝对大腿肌肉（r=-0.108）、绝对下躯干肌肉（r=-0.132）、相对大腿肌肉（r=-0.128）、相对下躯干肌肉（r=-0.126）、相对下肢 LBM（r=-0.108）和相对总 LBM（r=-0.082）呈负相关，与相对大腿 SAT（r=0.137）、相对下躯干 SAT（r=0.188）、相对下肢 FM（r=0.107）和相对总 FM（r=0.082）呈正相关。控制体力活动、吸烟、慢性疾病和年龄后，这些关系仍然显著。CAG(n) 与任何循环雄激素均无相关性。
CAG 重复多态性影响年轻男性的身体成分：随着 CAG(n) 的减少，绝对大腿肌肉和绝对下躯干肌肉增加。相对而言，肌肉面积和 LBM 增加，而 SAT 和 FM 减少。该多态性不影响年轻男性的深部脂肪组织或循环雄激素水平。
