Browsing Pathways

3-Hydroxyisobutyric aciduria, also called HIBA, is an extremely rare inherited inborn error of metabolism (IEM) of valine metabolism. Only 12-13 patients have been identified with this condition. It is an autosomal recessive disorder that may be caused, in some cases, by a defective aldehyde dehydrogenase 6 family member A1 (ALDH6A1) gene which codes for methylmalonate semialdehyde dehydrogenase (MMSDH). MMSDH is a mitochondrial methylmalonate semialdehyde dehydrogenase that plays a role in the valine and pyrimidine catabolism. This protein catalyzes the irreversible oxidative decarboxylation of malonate and methylmalonate semialdehydes to acetyl- and propionyl-CoA. Another possible cause of the disorder is a mutation in 3-hydroxyisobutyrate dehydrogenase, a mitochondrial enzyme which catalyzes the conversion of 3-hydroxyisobutyrate into methylmalonic semialdehyde, or in the conversion of the semialdehyde to propionyl-CoA. Individuals with this disorder have very high levels of 3-hydroxyisobutyric acid secreted in their urine. Other indications of organic acidemia are also present. Signs and symptoms of 3-hydroxyisobutyric aciduria include developmental delay, dysmorphic facial features, and brain abnormalities. The excretion of 3-hydroxyisobutyric acid in the urine can range from 170 to 390 mmol/mol of creatinine. Concentrations of free carnitine are also low, and esterified carnitine can be elevated in patients. Protein-restricted diets and carnitine supplementation have been tried with varying degrees of success.

3-Hydroxyisobutyric aciduria, also called HIBA, is an extremely rare inherited inborn error of metabolism (IEM) of valine metabolism. Only 12-13 patients have been identified with this condition. It is an autosomal recessive disorder that may be caused, in some cases, by a defective aldehyde dehydrogenase 6 family member A1 (ALDH6A1) gene which codes for methylmalonate semialdehyde dehydrogenase (MMSDH). MMSDH is a mitochondrial methylmalonate semialdehyde dehydrogenase that plays a role in the valine and pyrimidine catabolism. This protein catalyzes the irreversible oxidative decarboxylation of malonate and methylmalonate semialdehydes to acetyl- and propionyl-CoA. Another possible cause of the disorder is a mutation in 3-hydroxyisobutyrate dehydrogenase, a mitochondrial enzyme which catalyzes the conversion of 3-hydroxyisobutyrate into methylmalonic semialdehyde, or in the conversion of the semialdehyde to propionyl-CoA. Individuals with this disorder have very high levels of 3-hydroxyisobutyric acid secreted in their urine. Other indications of organic acidemia are also present. Signs and symptoms of 3-hydroxyisobutyric aciduria include developmental delay, dysmorphic facial features, and brain abnormalities. The excretion of 3-hydroxyisobutyric acid in the urine can range from 170 to 390 mmol/mol of creatinine. Concentrations of free carnitine are also low, and esterified carnitine can be elevated in patients. Protein-restricted diets and carnitine supplementation have been tried with varying degrees of success.

3-Methylcrotonyl-Coenzyme A Carboxylase Deficiency Type I also called 3-MCC Deficiency is a rare inborn error of metabolism (IEM) and is the result of defective pair of genes. More specifically defects in genes MCCC1 and MCCC2 cause 3-MCC Deficiency. 3-MCC has a very important role in protein metabolism in the body. In particular, the said enzyme is pivotal in one of the many steps which constitute the breakdown of leucine. Mutations in the aforementioned genes leads to a reduction in the activity of 3-MCC. As would naturally be expected, this causes the body to be unable to uptake and breakdown leucine properly. Consequently, this leads to the build up of toxic byproducts which are not processed as the breakdown of leucine is left incomplete. If these toxic byproducts manifest themselves in sufficiently high levels they can be very harmful, damaging the brain and nervous system. Symptoms include recurring episodes of vomiting and diarrhea, lethargy, hypotonia, seizures, and coma.

3-Methylcrotonyl-Coenzyme A Carboxylase Deficiency Type I also called 3-MCC Deficiency is a rare inborn error of metabolism (IEM) and is the result of defective pair of genes. More specifically defects in genes MCCC1 and MCCC2 cause 3-MCC Deficiency. 3-MCC has a very important role in protein metabolism in the body. In particular, the said enzyme is pivotal in one of the many steps which constitute the breakdown of leucine. Mutations in the aforementioned genes leads to a reduction in the activity of 3-MCC. As would naturally be expected, this causes the body to be unable to uptake and breakdown leucine properly. Consequently, this leads to the build up of toxic byproducts which are not processed as the breakdown of leucine is left incomplete. If these toxic byproducts manifest themselves in sufficiently high levels they can be very harmful, damaging the brain and nervous system. Symptoms include recurring episodes of vomiting and diarrhea, lethargy, hypotonia, seizures, and coma.

3-Methylglutaconic aciduria type 1 (3-Methylglutaconicaciduria; Aciduria, 3-methylglutaconic type I) is an autosomal recessive disease caused by a mutation in the AUH gene which codes for methylglutaconyl-CoA hydratase. A deficiency in this enzyme results in accumulation of 3-hydroxyisovaleric acid, 3-methylglutaconic acid, and methylglutaric acid in urine. Symptoms include hypoglycemia, low birth weight, coma, seizures, and mental retardation. Treatment includes a low protein diet.

3-Methylglutaconic aciduria type 1 (3-Methylglutaconicaciduria; Aciduria, 3-methylglutaconic type I) is an autosomal recessive disease caused by a mutation in the AUH gene which codes for methylglutaconyl-CoA hydratase. A deficiency in this enzyme results in accumulation of 3-hydroxyisovaleric acid, 3-methylglutaconic acid, and methylglutaric acid in urine. Symptoms include hypoglycemia, low birth weight, coma, seizures, and mental retardation. Treatment includes a low protein diet.

3-Methylglutaconic aciduria type 3 (Costeff syndrome; Optic atrophy plus syndrome) is an autosomal recessive disease caused by a deficiency in the OPA3 code which does for optic atrophy 3 protein. A deficiency of this enzyme results in accumulation of 3-methylglutaconic acid and methylglutaric acid. Symptoms include ataxia, dysarthria, optic atrophy, and neurological deterioration.

3-Methylglutaconic aciduria type 3 (Costeff syndrome; Optic atrophy plus syndrome) is an autosomal recessive disease caused by a deficiency in the OPA3 code which does for optic atrophy 3 protein. A deficiency of this enzyme results in accumulation of 3-methylglutaconic acid and methylglutaric acid. Symptoms include ataxia, dysarthria, optic atrophy, and neurological deterioration.

3-Methylglutaconic Aciduria Type IV, also called MGA, Type IV and MGA4, is a rare inborn error of metabolism (IEM) and autosomal recessive disorder and caused by a defective methylglutaconyl-CoA hydratase. Methylglutaconyl-CoA hydratase catalyzes the conversion of 3-Methylglutaconyl-CoA into 3-Hydroxy-3-methylglutaryl-CoA which is the substrate of hydroxymethylglutaryl-CoA lyase. This disorder is characterized by increased urinary excretion of 3-methylglutaconic acid. Symptoms of the disorder include poor growth and neurological degression. Currently, there is no effective treatment for 3-MGA type IV.

3-Methylglutaconic Aciduria Type IV, also called MGA, Type IV and MGA4, is a rare inborn error of metabolism (IEM) and autosomal recessive disorder and caused by a defective methylglutaconyl-CoA hydratase. Methylglutaconyl-CoA hydratase catalyzes the conversion of 3-Methylglutaconyl-CoA into 3-Hydroxy-3-methylglutaryl-CoA which is the substrate of hydroxymethylglutaryl-CoA lyase. This disorder is characterized by increased urinary excretion of 3-methylglutaconic acid. Symptoms of the disorder include poor growth and neurological degression. Currently, there is no effective treatment for 3-MGA type IV.