Browsing Pathways

2-Methyl-3-hydroxybutyryl CoA dehydrogenase deficiency (Hydroxyl-CoA dehydrogenase deficiency; MHBD) is a rare inborn disease of metabolism caused by a mutation in the HSD17B10 gene which codes for 3-hydroxyacyl-CoA dehydrogenase type-2. A deficiency in this enzyme results in accumulation of L-lactic acid in blood, spinal fluid, and urine; 2-ethylhydracrylic acid, 2-methyl-3-hydroxybutyric acid, and tiglylglycine in urine. Symptoms include cerebal atrophy, motor and mental retardation, overactivity and behavior issues, seizures and progressive neurological defects leading to early death. Treatment includes a high carbohydrate and low protein diet.

3-Hydroxy-3-methylglutaryl-CoA lyase deficiency (3-Hydroxy-3-methylglutaric acidemia; Leucine metabolism, defect in, HMG-CoA lyase deficiency) is an autosomal recessive disease caused by a mutation in the HMGCL gene which codes for hydroxymethylglutaryl-CoA lyase. A deficiency in this enzyme results in accumulation of 3-hydroxymethylglutaric acid, 3-hydroxyisovaleric acid, 3-methylcrotonylglycine and 3-methylglutaconic acid (cis and trans form), and methylglutaric acid in urine; and ammonia in blood. Symptoms include cardiomyopathy, dehydration, hypotonia, lactic acidosis, and pancreatitis. Treatment includes a low-fat, low-protein, high-carbohydrate diet.

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 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.

4-Hydroxybutyric Aciduria/Succinic Semialdehyde Dehydrogenase Deficiency (SSADH; Gamma-hydroxybutyric acidemia) inhibits the formation of succinate from GABA. This deficiency results in urinary excretion of 4-hydroxybutyric acid. In vivo proton MR also indicates elevated GABA levels as compared with an age-matched control. Symptoms include ataxia, chorea or athetosis, motor retardation, seizures, macrocephaly and delayed or abnormal speech development.

5-Oxoprolinuria (5-Oxoprolinase deficiency) is a result of a defect in the gamma-glutamyl cycle due to either 5-oxoprolinase or glutathione synthetase deficiency. In the case of glutathione synthetase deficiency, the glycine is not incorporated into gamma-glutamylcysteine. In the case of 5-oxoprolinase, however, pyroglutamic acid accumulates. Symptoms include anemia, mental retardation, metabolic acidosis, respiratory distress and urolithiasis.

Acute intermittent porphyria (AIP), also called Swedish porphyria, is a rare inborn error of metabolism (IEM) and autosomal dominant disorder of heme biosynthesis caused by a defective HMBS gene. The HMBS gene codes for the protein hydroxymethylbilane synthase (porphobilinogen deaminase) which catalyzes the synthesis of porphobilinogen into hydroxymethylbilane. This disorder is characterized by a large accumulation of 5-aminolevulinic acid or porphobilinogen in both urine and serum. Most patients are asymptomatic between attacks. Symptoms of the disorder include abdominal pain, constipation, vomiting, hypertension, muscle weakness, seizures, delirium, coma, and depression. Treatment involves undertaking a high-carbohydrate diet and, during severe attacks, a glucose 10% infusion. It is estimated that AIP affects 5.9 per 1 000 000 people.

Adenosine deaminiase deficiency (immunodeficiency) is an autosomal recessive disease caused by a muation in the ADA gene which codes for adenosine deaminase. A deficiency in this enzyme results in immunodeficiency and a decreased concentration of lymphocytes in blood. Symptoms include diarrhea, severe or recurrent infections, vomiting and early onset in children, infants and newborns. Treatment includes bone-marrow transplants and enzyme replacement therapy.