The two phenotypes of citrin deficiency are citrullinemia type II (CTLN2) and neonatal intrahepatic cholestasis caused by citrin deficiency (NICCD). CTLN2 typically presents in adulthood with recurring neuropsychiatric symptoms associated with episodic hyperammonemia, including disorientation, irritability, delusions, delirium, seizures, and coma that can lead to death from brain edema. Onset is sudden usually between the ages of 20-50 and often prompted by medication, alcohol or surgery. The symptoms of NICCD are milder and present in children under one year of age as transient intrahepatic cholestasis, hypoproteinemia, growth retardation, hypoglycemia, fatty liver, mild liver dysfunction, and/or high levels of plasma alpha-fetoprotein. A few NICCD patients have a severe form of the disorder with liver damage associated with tyrosinemia and require liver transplantation. Most NICCD patients’ symptoms disappear by one year of age; however, some NICCD patients later develop CTLN2 with neuropsychiatric symptoms several decades later. Patients with both CTLN2 and NICCD tend to have a preference for protein-rich and lipid-rich foods and avoid sugar-rich and carbohydrate-rich foods. Some individuals with NICCD later develop severe CTLN2. The male to female ratio in CTLN2 is 2.4 to 1, while the ratio in NICCD is roughly equal. Citrin deficiency was once thought to be restricted to Japan where the carrier rate is 1 in 65. However, affected individuals in other countries have now been identified. The carrier rate is also high in the East Asian population: China (1 in 65), Taiwan (1 in 48) and Korea (1 in 112).