Although the role of myostatin in aging and other muscle-wasting conditions is unclear, skeletal muscle myostatin mRNA expression is higher in overweight and obese middle-aged and older adults with sarcopenia than in those without sarcopenia, and myostatin mRNA expression is positively correlated with BMI, fat mass, and mid-thigh intra-muscular fat area [147]. The gene discussed is MSTN; the disease is sarcopenia.