Association between-308 G/A TNF-α Polymorphism and Appendicular Skeletal Muscle Mass Index as a Marker of Sarcopenia in Normal Weight Obese Syndrome

Background and Aim. Normal weight obese (NWO) syndrome is characterized by normal bodymass index (BMI), but high amount of fat mass and reduced lean mass. We evaluated allelic frequency of the G/A -308 TNF-alpha polymorphism and prevalence of sarcopenia in NWO. Methods. We enrolled 120 Italian healthy women, distinguished into 3 groups: normal weight (NW); NWO, and preobese-obese (PreOB/OB) and evaluated anthropometric parameters, body composition by dual X-ray absorptiometry, blood tests, and genotyping of G/A -308 TNF-alpha polymorphism. Results. We found a positive association between sarcopenic obesity and -308 TNF-alpha polymorphism. All obese women were sarcopenic and were no carrier of mutation (G/G). Among all G/G, NWO showed significant differences in lean mass and total body lean mass (TBLean) with respect to NW and PreOB/OB (P < 0.001). Regarding appendicular skeletal muscle mass index values, 4.21% of NW were sarcopenic (50% G/G and 50% G/A); the same percentage was observed in NWO subjects (100% G/G). Moreover, 2.10% of PreOB/OB were sarcopenic and all were G/G. Conclusion. Our study suggests that TNF-alpha polymorphism contributes to sarcopenic obesity susceptibility, in association with body composition. This is the first study that shows the importance of TNF-alpha polymorphism to determine TBLean variation in NWO syndrome.