The term CITRIN was designated in 1999 to stand for the protein product encoded by SLC25A13 gene, which was localized to chromosome 7q21.3 and cloned as the causative gene for Adult-onset Citrullinemia Type 2 (CTLN2, OMIM #603471) [1]. The gene discussed is SLC25A13; the disease is citrullinemia type II.