Comparison of anthropometric and metabolic parameters (adipokine, liver enzymes, insulin and lipid metabolism) as well as of the percentage of pre-pubertal children with obesity and with diagnosed steatosis hepatis between the group of children with normal z-scores of circulating leptin levels (n=71) and the group of children with low z-scores of circulating leptin levels (n=26). The gene discussed is INS; the disease is obesity disorder.