In obesity group, early-puberty subgroup girls had significantly higher values (p < 0.05) for age, leptin, IGF-1, IGFBP3, insulin, HOMA-IR, FSH, LH, ratio LH/FSH, estradiol, ACTH, DHE-S, androstenediona, T and FT levels than prepubertal subgroup, and there were no significant differences in BMI-SDS, TSH, FT4, PL, cortisol and 17-OH-P levels among both subgroups. The gene discussed is IGF1; the disease is obesity due to melanocortin 4 receptor deficiency.