Succinic semialdehyde dehydrogenase (SSADH) deficiency is a rare inborn error of the GABA degradative pathway described in approximately 300 patients. The enzyme defect results in accumulation of 4-hydroxybutyric acid (GHB), a compound with unusual neuropharamacologic properties. Clinically, the phenotype is non-specific, featuring psychomotor retardation, hypotonia and speech delay. Currently, there is no effective treatment, and little is known about pathomechanisms or neuropathophysiology. To overcome these gaps in our knowledge, we will develop a murine model of SSADH deficiency and address the following Aims and questions: 1) what are the pathologic findings in the murine model and how do they correlate with the human disease? 2) what role does GHB play in the development of disease pathology?; and 3) can the murine model provide a useful vehicle for development of new preclinical treatment paradigms (encompassing pharmacologic, hematopoietic replacement and hepatocyte repopulation approaches).
These Aims address our long-term objective of developing effective treatment strategies for patients with SSADH deficiency. The research design encompasses development of the knockout followed by characterization of the biochemical/behavioral phenotype and therapeutic approaches at Oregon Health Sciences University with neurologic characterization at the Hospital for Sick Children in Toronto. This design brings considerable expertise to the proposal, employing biochemical, morphologic, enzymatic, molecular, histologic, behavioral, neurochemical and transplantation approaches. Our hypothesis is that GHB has a major role in disease pathology, because it is known that GHB interacts with many neurotransmitter receptors and signaling pathways. Many compounds which act in these systems, and which may have therapeutic value in SSADH-deficient patients are commercially available. Thus, the use of these drugs in a murine model of SSADH deficiency will provide insight into the pathophysiology of the disorder as well as potential new therapeutic strategies.

National Institute of Health (NIH)
National Institute of Neurological Disorders and Stroke (NINDS)
Research Project (R01)
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Special Emphasis Panel (ZRG1-BDCN-3 (01))
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Spinella, Giovanna M
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Oregon Health and Science University
Schools of Medicine
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Malaspina, P; Roullet, J-B; Pearl, P L et al. (2016) Succinic semialdehyde dehydrogenase deficiency (SSADHD): Pathophysiological complexity and multifactorial trait associations in a rare monogenic disorder of GABA metabolism. Neurochem Int 99:72-84
Goodwin, Amy K; Gibson, K Michael; Weerts, Elise M (2013) Physical dependence on gamma-hydroxybutrate (GHB) prodrug 1,4-butanediol (1,4-BD): time course and severity of withdrawal in baboons. Drug Alcohol Depend 132:427-33
Siggberg, Linda; Mustonen, Aki; Schuit, Robert et al. (2011) Familial 6p22.2 duplication associates with mild developmental delay and increased SSADH activity. Am J Med Genet B Neuropsychiatr Genet 156B:448-53
Pearl, Phillip L; Shukla, Lovy; Theodore, William H et al. (2011) Epilepsy in succinic semialdehyde dehydrogenase deficiency, a disorder of GABA metabolism. Brain Dev 33:796-805
Kim, Kyung-Jin; Pearl, Phillip L; Jensen, Kimmo et al. (2011) Succinic semialdehyde dehydrogenase: biochemical-molecular-clinical disease mechanisms, redox regulation, and functional significance. Antioxid Redox Signal 15:691-718
Wamelink, M M C; Roos, B; Jansen, E E W et al. (2011) 4-Hydroxybutyric aciduria associated with catheter usage: a diagnostic pitfall in the identification of SSADH deficiency. Mol Genet Metab 102:216-7
Errington, Adam C; Gibson, K Michael; Crunelli, Vincenzo et al. (2011) Aberrant GABA(A) receptor-mediated inhibition in cortico-thalamic networks of succinic semialdehyde dehydrogenase deficient mice. PLoS One 6:e19021
Knerr, Ina; Gibson, K Michael; Murdoch, Geoffrey et al. (2010) Neuropathology in succinic semialdehyde dehydrogenase deficiency. Pediatr Neurol 42:255-8
Vardya, Irina; Drasbek, Kim R; Gibson, K Michael et al. (2010) Plasticity of postsynaptic, but not presynaptic, GABAB receptors in SSADH deficient mice. Exp Neurol 225:114-22
Dósa, Zita; Nieto-Gonzalez, Jose Luis; Korshoej, Anders Rosendal et al. (2010) Effect of gene dosage on single-cell hippocampal electrophysiology in a murine model of SSADH deficiency (gamma-hydroxybutyric aciduria). Epilepsy Res 90:39-46

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