Interleukin-6 (IL6) Genotype Is Associated With Fat-Free Mass in Men But Not Women

We studied the association of the G-174C promoter polymorphism in the interleukin-6 gene (IL6) with total body fat and fat-free mass (FFM) in 242 men and women (IL6 genotypes: G/G, n 87; G/C, n 100; C/C, n 55) across the adult age span (21–92 years). In men, but not women (significant genotype by sex interactions; p .023–.048), the C/C group exhibited significantly lower total FFM than the G/G group (54.7 6 0.8 kg vs 57.2 6 0.7 kg, respectively, p .020), as well as significantly lower FFM of the lower limbs compared with the G/G group (18.4 6 0.3 kg vs 19.8 6 0.3 kg, respectively, p .004). No significant genotype differences were observed in total body fat mass in either men or women. The results indicate that the IL6 G-174C polymorphism is significantly associated with FFM in men but not women. RECENT reports have shown that sarcopenia, the lossof muscle mass and strength with advancing age, is common in older individuals and is associated with functional impairment and disability (1–3). Janssen and colleagues (1) recently reported that approximately 60 % of women and 45 % of men aged.60 years exhibited class I sarcopenia, equivalent to a skeletal muscle mass index belo