Reinehr et al. conducted a 1-year longitudinal follow-up study in a primary-care setting with 43 obese children and 19 lean children of the same age and sex based on exercise, behavior, and nutritional therapy and found that RBP4 levels were related to weight status and insulin resistance in both cross-sectional and longitudinal analyses, suggesting a relationship between RBP4 levels, obesity, and insulin resistance in children [132]. The gene discussed is RBP4; the disease is obesity due to melanocortin 4 receptor deficiency.