Sarcopenia was significantly associated with C5 as a categorical variable (third compared with lowest quartile) (odds ratio (95% confidence interval: 0.363 (0.153, 0.865), p = 0.0222) after adjusting for age, BMI, smoking status, malnutrition, cognition, and hemoglobin; however, the association was no longer significant after adjusting for the covariates of serum albumin, red blood cells. The gene discussed is ALB; the disease is malnutrition.