SOD1 and obesity due to melanocortin 4 receptor deficiency: Analyzing girls and boys separately (Figure 1), significant associations of obesity with serum MDA levels (β = 3.58 ± 1.16, p = 3.0 × 10−3) and SOD enzyme activity (β = 12.13 ± 4.41, p = 7.0 × 10−3) were only observed for boys.