4-HYDROXYBUTYRIC ACIDURIA - CLINICAL FINDINGS AND VIGABATRIN THERAPY

Succinic semialdehyde dehydrogenase deficiency (SSADH) (EC 1.2.1.24, M cKusick 271980) is a rare autosomal recessive inherited disorder chara cterized by increased levels of 4-hydroxybutyric acid in plasma, CSF a nd urine. SSADH, an enzyme of the degradative pathway of GABA, catalys es the formation of succinic acid from succinic semialdehyde. In 17 pa tients affected by deficiency of SSADH previously reported, the major clinical findings are psychomotor retardation, hypotonia, ataxia, chor eoathetosis and variable degree of mental retardation; almost 50% of t hem come from the Mediterranean area. The antiepileptic drug gamma-vin yl-GABA, an irreversible inhibitor of GABA-transaminase (the enzyme pr eceding SSADH), has been tried in three reported patients (Gibson et a l 1989; Jaeken et al 1989; Jakobs et al 1992), with the aim of reducin g the accumulation of 4-hydroxybutyric acid. We report the clinical fe atures, biochemical data and results of vigabatrin therapy in a new It alian patient.