ALDH5A1 and hyperinsulinemic hypoglycemia, familial, 4: Succinic semialdehyde dehydrogenase (SSADH) deficiency (OMIM #271980), also known as 4-hydroxybutyric aciduria, is an autosomal recessive disorder in the degradation pathway of γ-aminobutyric acid (GABA): the central nervous system’s predominant inhibitory neurotransmitter [1–3].