GCDH and glutaryl-CoA dehydrogenase deficiency: MALDI-MSI and MALDI-IRIS were used to study two related IMDs inthe l-lysine catabolism pathway: pyridoxine-dependent epilepsy(PDE-ALDH7A1) and glutaric aciduria type 1 (GA1).These disorders are caused by mutations in ALDH7A1 and GCDH, which encode the enzymes antiquitin and GCDH, respectively.