In the United States, NAFLD prevalence ranges from 9.6% of all children aged between 2 and 19 years to 38.0% of obese children when fatty liver is defined by the presence of overweight (BMI ≥ 95th percentile) and elevated ALT concentrations: more than 25.8 IU/L for boys and more than 22.1 IU/L for girls [33,34]. The gene discussed is GPT; the disease is fatty liver disease.