encephalopathy

ETHE1, also known as HSCO, is a sulfur dioxygenase that localizes within the mitochondrial matrix. ETHE1 probably plays an important role in metabolic homeostasis in mitochondria. It may also function as a nuclear-cytoplasmic shuttling protein that binds transcription factor RELA/NFKB3 in the nucleus and exports it to the cytoplasm. ETHE1 can suppresses p53-induced apoptosis by preventing nuclear localization of RELA. Mutations in ETHE1 gene result in ethylmalonic encephalopathy. Ethylmalonic encephalopathy is an autosomal recessive, invariably fatal disorder characterized by early-onset encephalopathy, microangiopathy, chronic diarrhea, defective cytochrome c oxidase (COX) in muscle and brain, high concentrations of C4 and C5 acylcarnitines in blood and high excretion of ethylmalonic acid in urine.

Syntaxin-binding protein 1, also known as N-Sec1, Protein unc-18 homolog 1, MUNC18-1 and STXBP1, is a peripheral membrane protein that belongs to the STXBP / unc-18 / SEC1 family. STXBP1 is an evolutionally conserved neuronal Sec1/Munc-18 (SM) protein that is essential in synaptic vesicle release in several species. It may participate in the regulation of synaptic vesicle docking and fusion, possibly through interaction with GTP-binding proteins. STXBP1 is essential for neurotransmission and binds syntaxin, a component of the synaptic vesicle fusion machinery probably in a 1:1 ratio. It can interact with syntaxins 1, 2, and 3 but not syntaxin 4. STXBP1 may also play a role in determining the specificity of intracellular fusion reactions. Defects in STXBP1 are the cause of epileptic encephalopathy early infantile type 4 (EIEE4). Affected individuals have neonatal or infantile onset of seizures, suppression-burst pattern on EEG, profound mental retardation, and MRI evidence of hypomyelination.

Fumarate Hydratase (FH) is an enzymatic component of the tricarboxylic acid (TCA) cycle, or Krebs cycle, and catalyzes the formation of L-malate from fumarate. It exists in both a cytosolic form and an N-terminal extended form, differing only in the translation start site used. The N-terminal extended form is targeted to the mitochondrion, where the removal of the extension generates the same form as in the cytoplasm. Fumarate Hydratase is similar to some thermostable class II fumarases and functions as a homotetramer. Mutations in this gene can cause fumarase deficiency and lead to progressive encephalopathy. Individuals with hemizygous germline fumarate hydratase (FH) mutations are predisposed to renal cancer. These tumors predominantly exhibit functional inactivation of the remaining wild-type allele, implicating FH inactivation as a tumor-promoting event.

Fumarase is an enzyme that catalyze the reversible hydration/dehydration of fumarate to S-malate and is involved in the tricarboxylic acid or Krebs cycle. Fumarase exists in both form, cytosolic formand N-terminal extend mitochondrial form. The N-terminal extended form is targeted to the mitochondrion, where the removal of the extension is the same form as in the cytoplasm. Fumarase is thought to act as a tumor suppressor, which deficiency can lead to progressive encephalopathy, cerebral atrophy and development delay.

Medium-Chain Specific Acyl-CoA Dehydrogenase (ACADM) is a mitochondrial fatty acid beta-oxidation that belongs to the acyl-CoA dehydrogenase family. ACADM is a homotetramer enzyme that catalyzes the initial step of the mitochondrial fatty acid beta-oxidation pathway. ACADM is specific for acyl chain lengths of 4 to 16. It is essential for converting these particular fatty acids to energy, especially during fasting periods. Defects in ACADM cause medium-chain acyl-CoA dehydrogenase deficiency, a disease characterized by hepatic dysfunction, fasting hypoglycemia, and encephalopathy, which can result in infantile death.

Prion protein gene (PRNP) variants determine the susceptibility of humans, sheep and mice to prion diseases, whereas polymorphisms in the open reading frame (ORF) of bovine PRNP seem to be unrelated to the incidence of bovine spongiform encephalopathy (BSE). According to the latest reports, the genetic susceptibility of cattle to BSE is associated with polymorphisms ofthe regulatory region of the PRNP gene and the level ofits expression.

Thiamine pyrophosphokinase (TPK) produces thiamine pyrophosphate, a cofactor for a number of enzymes, including pyruvate dehydrogenase and 2-ketoglutarate dehydrogenase. Episodic encephalopathy type thiamine metabolism dysfunction (OMIM 614458) due to TPK1 mutations is a recently described rare disorder. The genomic variations in the fetal and maternal TPK1 gene could contribute to the variability of birth weight in normal humans.