SLC25A13 and neonatal intrahepatic cholestasis due to citrin deficiency: By contrast, the second isoform of the mitochondrial aspartate/glutamate carrier, AGC2 [5], encoded by the SLC25A13 gene, is mainly expressed in liver and mutations in this gene lead to neonatal intrahepatic cholestasis caused by citrin deficiency (NICCD) and adult-onset type II citrullinemia (CTLN2) [7].