To test this hypothesis it would be ideal to perform a standardized analysis of these patients including an accurate clinical evaluation (especially necessary for P5CS deficiency, where the clinical heterogeneity is high), plasma aminoacid profile analysis in fasting and non-fasting conditions, and H-RMS to check for alterations in in vivo metabolite concentrations in the central nervous system. This evidence concerns the gene ALDH18A1 and hyperinsulinemic hypoglycemia, familial, 4.