When subjects were stratified into hypoalbuminemia and normal albumin groups, we found that the association between S-Alb and MG remained significant in the hypoalbuminemia group only (OR: 0.693, 95% CI: 0.550–0.874, P = 0.002) after further adjustment for age, sex, BMI, and duration of disease. This evidence concerns the gene ALB and myasthenia gravis.