LEP and obesity due to melanocortin 4 receptor deficiency: While one small case-control study showed greater serum leptin concentrations among adults with asthma than controls (mean values 24.8 versus 13.7 ng/mL) [70], others failed to show any difference in serum or BAL leptin concentrations between the two groups, after adjusting for obesity [25, 36, 71, 72, 116].