ALDH6A1 | |||||||||||||||||||||||||||||||||||||||||||||||||||
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Aliases | ALDH6A1 , MMSADHA, MMSDH, Aldehyde dehydrogenase 6 family, member A1, aldehyde dehydrogenase 6 family member A1 | ||||||||||||||||||||||||||||||||||||||||||||||||||
External IDs | OMIM: 603178 MGI: 1915077 HomoloGene: 4082 GeneCards: ALDH6A1 | ||||||||||||||||||||||||||||||||||||||||||||||||||
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Wikidata | |||||||||||||||||||||||||||||||||||||||||||||||||||
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Methylmalonate-semialdehyde dehydrogenase [acylating], mitochondrial (MMSDH) is an enzyme that in humans is encoded by the ALDH6A1 gene. [5] [6]
This protein belongs to the aldehyde dehydrogenases family of proteins. This enzyme plays a role in the valine and pyrimidine catabolic pathways. The product of this gene, a mitochondrial methylmalonate semialdehyde dehydrogenase, catalyzes the irreversible oxidative decarboxylation of malonate and methylmalonate semialdehydes to acetyl- and propionyl-CoA. Methylmalonate semialdehyde dehydrogenase deficiency is characterized by elevated beta-alanine, 3-hydroxypropionic acid, and both isomers of 3-amino and 3-hydroxyisobutyric acids in urine organic acids. [6] Methylmalonate semialdehyde dehydrogenase deficiency is caused by mutations in this gene and the resulting protein. [7]
The ALDH6A1 gene is mapped onto 14q24.3, between markers D14S71 and D14S986, and has an exon count of 12. [8] [6] The mRNA expression levels of this gene are highest in the kidney and liver, although mRNA levels have been found in many other tissues. The mature protein that this gene translates in humans is 503 amino acids long, which is similar to other enzymes of this family, which all comprise around 500 amino acids. This enzyme localizes to the mitochondria. Unlike other mitochondrial entry sequences, this does not contain as many arginine residues, and is in fact slightly longer. [7]
MMSDH has esterase activity, which is characteristic of the enzymes in the Aldehyde Dehydrogenase family. It is more specifically involved in the valine and thymine catabolism pathways. When the enzyme acts on valine, (S)-3-hydroxyisobutyric acid is generated as an intermediate; this then undergoes oxidation by the enzyme 3-hydroxyisobutyrate dehydrogenase to form (S)-methylmalonic semialdehyde (MMSA). In thymine catabolism, the enzymatic reaction produces (R)-aminoisobutyric acid (AIBA), which is then deaminated to (R)-methylmalonic semialdehyde. These two enantiomers of MMSA are substrates for MMSDH, which catalyzes their oxidative decarboxylation to propionyl-CoA. [9] Both NAD+ and CoA act as cofactors with the enzyme, although they work in opposite directions; NAD+ works to protect the enzyme against proteolysis, but CoA esters diminish that effect. [10]
Mutations in the ALDH6A1 gene are associated with methylmalonate semialdehyde dehydrogenase deficiency, a rare autosomal recessive inborn error of metabolism with a highly variable phenotype. The disease is passed through autosomal recessive genetics. There have been many individual and familial case studies of this deficiency and the mutations that cause it. Some patients with this disease may be asymptomatic, whereas others show global developmental delay, nonspecific dysmorphic features, and delayed myelination on brain imaging. Meanwhile, some cases have been only identified through elevated levels of various acidic metabolites in the urine, notably 3-hydroxyisobutyric acid. [7] [11] This can result from an identified a homozygous 1336G-A transition in the gene, resulting in a change in the 446th residue from glycine to arginine. [12] Another case study, a child from consanguineous patients, presented as significant hypotonia in infancy, poor feeding, and dysmorphic facial features, including narrowed, downslanting palpebral fissures, short convex nose with depressed nasal bridge, microphthalmia, cataracts, and adducted thumbs. Brain imaging showed delayed myelination and thinning of the corpus callosum. Laboratory studies showed 3-hydroxyisobutyric aciduria and mild lactic acidosis. [13] Many case studies since then have presented similar symptoms, although the symptoms may be milder. [14] The mutations identified are generally heterozygous missense mutations: S262Y, P62S, Y172H and R535C. [7]
Methylmalonic acidemia, also called methylmalonic aciduria, is an autosomal recessive metabolic disorder that disrupts normal amino acid metabolism. It is a classical type of organic acidemia. The result of this condition is the inability to properly digest specific fats and proteins, which in turn leads to a buildup of a toxic level of methylmalonic acid in the blood.
Propionic acidemia, also known as propionic aciduria or propionyl-CoA carboxylase deficiency, is a rare autosomal recessive metabolic disorder, classified as a branched-chain organic acidemia.
Isovaleric acidemia is a rare autosomal recessive metabolic disorder which disrupts or prevents normal metabolism of the branched-chain amino acid leucine. It is a classical type of organic acidemia.
2-hydroxyglutaric aciduria is a rare neurometabolic disorder characterized by the significantly elevated levels of hydroxyglutaric acid in one's urine. It is either autosomal recessive or autosomal dominant.
Aldehyde dehydrogenases are a group of enzymes that catalyse the oxidation of aldehydes. They convert aldehydes to carboxylic acids. The oxygen comes from a water molecule. To date, nineteen ALDH genes have been identified within the human genome. These genes participate in a wide variety of biological processes including the detoxification of exogenously and endogenously generated aldehydes.
Succinic semialdehyde dehydrogenase deficiency (SSADHD) is a rare autosomal recessive disorder of the degradation pathway of the inhibitory neurotransmitter γ-aminobutyric acid, or GABA. The disorder has been identified in approximately 350 families, with a significant proportion being consanguineous families. The first case was identified in 1981 and published in a Dutch clinical chemistry journal that highlighted a number of neurological conditions such as delayed intellectual, motor, speech, and language as the most common manifestations. Later cases reported in the early 1990s began to show that hypotonia, hyporeflexia, seizures, and a nonprogressive ataxia were frequent clinical features as well.
Methylmalonyl-CoA mutase (EC 5.4.99.2, MCM), mitochondrial, also known as methylmalonyl-CoA isomerase, is a protein that in humans is encoded by the MUT gene. This vitamin B12-dependent enzyme catalyzes the isomerization of methylmalonyl-CoA to succinyl-CoA in humans. Mutations in MUT gene may lead to various types of methylmalonic aciduria.
Fatty aldehyde dehydrogenase is an aldehyde dehydrogenase enzyme that in human is encoded in the ALDH3A2 gene on chromosome 17. Aldehyde dehydrogenase enzymes function to remove toxic aldehydes that are generated by the metabolism of alcohol and by lipid peroxidation.
Aldehyde dehydrogenase, mitochondrial is an enzyme that in humans is encoded by the ALDH2 gene located on chromosome 12. This protein belongs to the aldehyde dehydrogenase family of enzymes. Aldehyde dehydrogenase is the second enzyme of the major oxidative pathway of alcohol metabolism. Two major liver isoforms of aldehyde dehydrogenase, cytosolic and mitochondrial, can be distinguished by their electrophoretic mobilities, kinetic properties, and subcellular localizations.
ACADSB is a human gene that encodes short/branched chain specific acyl-CoA dehydrogenase (SBCAD), an enzyme in the acyl CoA dehydrogenase family.
Organic acidemia, is a term used to classify a group of metabolic disorders which disrupt normal amino acid metabolism, particularly branched-chain amino acids, causing a buildup of acids which are usually not present.
Aldehyde dehydrogenase, dimeric NADP-preferring is an enzyme that in humans is encoded by the ALDH3A1 gene.
Succinate-semialdehyde dehydrogenase, mitochondrial is an enzyme that in humans is encoded by the ALDH5A1 gene.
Delta-1-pyrroline-5-carboxylate synthetase (P5CS) is an enzyme that in humans is encoded by the ALDH18A1 gene. This gene is a member of the aldehyde dehydrogenase family and encodes a bifunctional ATP- and NADPH-dependent mitochondrial enzyme with both gamma-glutamyl kinase and gamma-glutamyl phosphate reductase activities. The encoded protein catalyzes the reduction of glutamate to delta1-pyrroline-5-carboxylate, a critical step in the de novo biosynthesis of proline, ornithine and arginine. Mutations in this gene lead to hyperammonemia, hypoornithinemia, hypocitrullinemia, hypoargininemia and hypoprolinemia and may be associated with neurodegeneration, cataracts and connective tissue diseases. Alternatively spliced transcript variants, encoding different isoforms, have been described for this gene. As reported by Bruno Reversade and colleagues, ALDH18A1 deficiency or dominant-negative mutations in P5CS in humans causes a progeroid disease known as De Barsy Syndrome.
L-2-hydroxyglutarate dehydrogenase, mitochondrial is an enzyme that in humans is encoded by the L2HGDH gene, also known as C14orf160, on chromosome 14.
Alpha-aminoadipic semialdehyde synthase is an enzyme encoded by the AASS gene in humans and is involved in their major lysine degradation pathway. It is similar to the separate enzymes coded for by the LYS1 and LYS9 genes in yeast, and related to, although not similar in structure, the bifunctional enzyme found in plants. In humans, mutations in the AASS gene, and the corresponding alpha-aminoadipic semialdehyde synthase enzyme are associated with familial hyperlysinemia. This condition is inherited in an autosomal recessive pattern and is not considered a particularly negative condition, thus making it a rare disease.
Aldehyde dehydrogenase 8 family, member A1 also known as ALDH8A1 is an enzyme that in humans is encoded by the ALDH8A1 gene.
Aldehyde dehydrogenase 7 family, member A1, also known as ALDH7A1 or antiquitin, is an enzyme that in humans is encoded by the ALDH7A1 gene. The protein encoded by this gene is a member of subfamily 7 in the aldehyde dehydrogenase gene family. These enzymes are thought to play a major role in the detoxification of aldehydes generated by alcohol metabolism and lipid peroxidation. This particular member has homology to a previously described protein from the green garden pea, the 26g pea turgor protein. It is also involved in lysine catabolism that is known to occur in the mitochondrial matrix. Recent reports show that this protein is found both in the cytosol and the mitochondria, and the two forms likely arise from the use of alternative translation initiation sites. An additional variant encoding a different isoform has also been found for this gene. Mutations in this gene are associated with pyridoxine-dependent epilepsy. Several related pseudogenes have also been identified.
Acyl-CoA synthetase family member 3 is an enzyme that in humans is encoded by the ACSF3 gene.
Combined malonic and methylmalonic aciduria (CMAMMA), also called combined malonic and methylmalonic acidemia is an inherited metabolic disease characterized by elevated levels of malonic acid and methylmalonic acid. Some researchers have hypothesized that CMAMMA might be one of the most common forms of methylmalonic acidemia, and possibly one of the most common inborn errors of metabolism. Due to being infrequently diagnosed, it most often goes undetected.