Androgen receptor gene repeats and indices of obesity in older adults

OBJECTIVE: To examine the relationship between GGN and CAG trinucleotide repeat polymorphisms in the androgen receptor (AR) gene and indices of obesity in older Caucasian adults. DESIGN: A cross-sectional study. SUBJECTS: Ninety-nine healthy men (age 51 - 93 y) and 113 healthy postmenopausal women (age 51-92y). MEASUREMENTS: Genotyping the GGN and CAG repeats of the AR gene, and measuring body weight, height and waist and hip circumferences. Waist was measured at the umbilicus (wstumb), iliac crest (wstili), and mid-way between the iliac crest and lowest rib (wstwst). Waist-to-hip ratios (WHRUMB, WHRILI and WHRWST) and body mass index (BMI) were calculated. RESULTS: Women who were homozygous for a common GGN (117 or 18) and short CAG (:: 25) had higher waist and hip circumferences and higher WHRUMB and WHRWST, compared with women without this allele combination. The odds ratios (OR) for the upper 25th percentile of obesity measures were 3.6 -5.6-fold higher for wstumb, wstwst, WHRUMB and WHRWST among women with this allele combination. Men who had both a rare GGN (not 17) and short CAG (: 23) had a higher WHRUMB and WHRILI compared with men without this allele combination. The OR related to the upper 10th percentile of obesity measures among men who had this allele combination was 4.7-fold higher for WHRILI. CONCLUSION: AR GGN and CAG allele combinations are strongly associated with central obesity indices in older adults, particularly in women.