Citrin deficiency is a rare autosomal recessive disorder that arises from a lack of function of the hepatic mitochondrial aspartate/glutamate transporter 2 (AGC2), which supplies aspartate to the cytosol for the argininosuccinate synthetase reaction, in which aspartate and citrulline condense to produce argininosuccinate [21,164,165]. This evidence concerns the gene SLC25A13 and hyperinsulinemic hypoglycemia, familial, 4.