SLC25A13 and Failure to thrive: Citrin deficiency (CD) is an autosomal recessive disorder caused by pathogenic mutations of the SLC25A13 gene [1] and presents with age-dependent clinical manifestations [2–4]: neonatal intrahepatic cholestasis by CD (NICCD: OMIM #605814), failure to thrive and dyslipidemia by CD (FTTDCD), and an adult form known as adult-onset Type II citrullinemia (CTLN2, OMIM #603471), which has recently received the new terminology “adolescent and adult citrin deficiency” (AACD) [5] to avoid potentially tragic confusion with classical citrullinemia Type I [6].