CD4 and obesity due to melanocortin 4 receptor deficiency: Interestingly, the higher the BMI, the lower the CD4+ Treg percentage, with Class IV obesity showing the lowest value (nOB: 0.89% ± 0.3; II: 0.69 ± 0.36; III: 0.70 ± 0.27; IV: 0.63% ± 0.9; nOB vs. IV, p < 0.05; Figure 8B).