Citrin deficiency (CD), a recessive disease caused by mutations in the SLC25A13 gene, is characterized by three different age-dependent phenotypes: (a) neonatal intrahepatic cholestasis; (b) failure to thrive and dyslipidemia in children; and (c) citrullinemia type 2, with hyperammonemic attacks in adolescent or adult patients. The gene discussed is SLC25A13; the disease is citrin deficiency.