Compared with individuals with class I obesity, adjusted OR of markedly increased ALT was greater in those with class II obesity (OR: 1.82, 99% CI: 1.51 to 2.20, p < 0.001) and greatest in class III obesity (OR: 3.38, 99% CI 2.71 to 4.23, p < 0.001). The gene discussed is GPT; the disease is obesity due to melanocortin 4 receptor deficiency.