Biallelic SLC25A13 mutations result in citrin deficiency (CD), a disease entity with three age-dependent clinical phenotypes, i.e. Neonatal Intrahepatic Cholestasis caused by Citrin Deficiency (NICCD, OMIM#605814) in neonates or infants [7–9], adult-onset citrullinemia type II (CTLN2, OMIM#603471) in adolescents/adults [1], and Failure to Thrive and Dyslipidemia caused by Citrin Deficiency (FTTDCD) between NICCD and CTLN2 stages [10–14]. The gene discussed is SLC25A13; the disease is citrin deficiency.