We therefore evaluated circulating levels of IL-12 in Mexican normal weight, overweight, and obese individuals, examining their correlation with obesity-related parameters (fasting glucose, fasting insulin, insulin resistance, total cholesterol, total triglyceride, BMI, waist circumference, and body fat percentage) and low-grade inflammation markers (serum TNF-α and leptin). The gene discussed is LEP; the disease is obesity due to melanocortin 4 receptor deficiency.