Vigabatrin and newer interventions in succinic semialdehyde dehydrogenase deficiency.
Succinic semialdehyde dehydrogenase (SSADH) deficiency is a rare disorder characterized by an inborn error of the catabolism of the inhibitory neurotransmitter GABA. Because of the deficiency of SSADH, the final enzyme of the GABA degradation pathway, the substrate, succinic semialdehyde, is shunted towards production of 4-hydroxybutyric acid (gamma-hydroxybutyric acid). Elevations of gamma-hydroxybutyric acid can be detected in the physiologic fluids of patients with SSADH deficiency, and forms the mainstay of diagnosis. The clinical features of SSADH deficiency include nonspecific neurologic manifestations such as mental retardation/developmental delay, absent speech, hypotonia, nonprogressive ataxia, features of autism or pervasive developmental delay, developmental language delay (dyspraxia, receptive, and expressive delays), and occasionally, seizures. Although the metabolic pathway has been established, it is not known whether insufficient GABA and/or excess gamma-hydroxybutyric acid contribute to the disease phenotype. Pharmacological therapy in patients with this disorder has been limited to vigabatrin, an anticonvulsant that blocks GABA transaminase. This review will discuss therapeutic options in SSADH deficiency, on the basis of patient experience, and preliminary work using a murine model. Finally, a discussion of adjunctive therapies will be included.
Gropman
Andrea
A
Neurogenetics Branch, Section on Neuronal Migration, National Institute of Neurological Diseases and Stroke, National Institutes of Health, Bethesda, MD 20892, USA. gropmana@ninds.nih.gov
D000445:Aldehyde Oxidoreductases / Q000172:deficiency* / Q000235:genetics*; D000592:Amino Acid Metabolism, Inborn Errors / Q000188:drug therapy* / Q000235:genetics*; D000818:Animals; D000927:Anticonvulsants / Q000009:adverse effects / Q000627:therapeutic use*; D002986:Clinical Trials as Topic; D004359:Drug Therapy, Combination; D006801:Humans; D050644:Succinate-Semialdehyde Dehydrogenase; D020888:Vigabatrin / Q000009:adverse effects / Q000627:therapeutic use*; D005680:gamma-Aminobutyric Acid / Q000378:metabolism*
D000927:Anticonvulsants; D005680:gamma-Aminobutyric Acid; D000445:Aldehyde Oxidoreductases; C493643:ALDH5A1 protein, human; D050644:Succinate-Semialdehyde Dehydrogenase; D020888:Vigabatrin