Browsing Pathways

Hereditary coproporphyria (HCP) is a rare inborn error of metabolism (IEM) which arises from a defective gene called CPOX. This gene is responsible for mitochondrial coproporphyrinogen-III oxidase. A defect in this enzyme results in accumulation of the porphyrin precursors porphobilinogen and 5-aminolevulinic acid; increase of fecal and urinary excreation of coproporphyrins. Symptoms for this condition vary substantially, with anything from reddish-purple urine, to bouts of acute abdominal and nerve pain, to episodes of photosensitive skin eruptions so extreme that the induced scratching often leads to permanent scarring. At the present time the condition has no cure. The following are some measures which are designed to help prevent and/or regulate the above and more symptoms: a diet which is high in carbohydrates and sugars, and a balanced lifestyle which abstains from alcohol and drug use.

Hereditary coproporphyria (HCP) is a rare inborn error of metabolism (IEM) which arises from a defective gene called CPOX. This gene is responsible for mitochondrial coproporphyrinogen-III oxidase. A defect in this enzyme results in accumulation of the porphyrin precursors porphobilinogen and 5-aminolevulinic acid; increase of fecal and urinary excreation of coproporphyrins. Symptoms for this condition vary substantially, with anything from reddish-purple urine, to bouts of acute abdominal and nerve pain, to episodes of photosensitive skin eruptions so extreme that the induced scratching often leads to permanent scarring. At the present time the condition has no cure. The following are some measures which are designed to help prevent and/or regulate the above and more symptoms: a diet which is high in carbohydrates and sugars, and a balanced lifestyle which abstains from alcohol and drug use.

Histidinemia (Histidine Ammonia-Lyase Deficiency; HAL Deficiency; Histidase Deficiency; HIS Deficiency) is an autosomal recessive disease caused by a mutation in the HAL gene which codes for hisitidine ammonia-lyase. A deficiency in this enzyme results in accumulation of L-histidine in serum, spinal fluid, and urine; histamine in plasma and urine; and imidazoleacetic acid, imidazolactic acid, and 1-methylhistamine in urine. Symptoms include organic acids in urine, mental retardation, and delayed speech development. Treatment includes a low-histamine diet.

Histidinemia (Histidine Ammonia-Lyase Deficiency; HAL Deficiency; Histidase Deficiency; HIS Deficiency) is an autosomal recessive disease caused by a mutation in the HAL gene which codes for hisitidine ammonia-lyase. A deficiency in this enzyme results in accumulation of L-histidine in serum, spinal fluid, and urine; histamine in plasma and urine; and imidazoleacetic acid, imidazolactic acid, and 1-methylhistamine in urine. Symptoms include organic acids in urine, mental retardation, and delayed speech development. Treatment includes a low-histamine diet.

Homocarnosinosis is caused by an inherited defect in serum carnosinase, which converts homocarnosine to GABA (gamma aminobutyric acid). A defect in serum carnosinase causes accumulation of the brain specific dipeptide homocarnosine (Hca), in the CSF and brain. Symptoms include hypotonia, mental retardation, retinitis pigmentosa and spastic diplegia/quadriplegia.

Homocarnosinosis is caused by an inherited defect in serum carnosinase, which converts homocarnosine to GABA (gamma aminobutyric acid). A defect in serum carnosinase causes accumulation of the brain specific dipeptide homocarnosine (Hca), in the CSF and brain. Symptoms include hypotonia, mental retardation, retinitis pigmentosa and spastic diplegia/quadriplegia.

Homocystinuria, Cystathionine beta-Synthase Deficiency, also known as homocystinuria, is a inherited disorder of amino acid methionine metabolism caused by a defective cystathionine beta-Synthase. Cystathionine beta-Synthase catalyzes the conversion of homocysteine and L-Serine into L-Cystathionine which is the substrate of cystathionine gamma-lyase. This disorder is characterized by a large accumulation of homocysteine in the cell. Symptoms of the disorder include thromboembolism, ectopia lentis and/or severe myopia, skeletal system deficiency and developmental delay. Treatment with homocystinuria aims at correct the biochemical abnormalities through disorder management (e.g. surveillance, circumstances to avoid, prevention of primary manifestations, etc.

Homocystinuria, Cystathionine beta-Synthase Deficiency, also known as homocystinuria, is a inherited disorder of amino acid methionine metabolism caused by a defective cystathionine beta-Synthase. Cystathionine beta-Synthase catalyzes the conversion of homocysteine and L-Serine into L-Cystathionine which is the substrate of cystathionine gamma-lyase. This disorder is characterized by a large accumulation of homocysteine in the cell. Symptoms of the disorder include thromboembolism, ectopia lentis and/or severe myopia, skeletal system deficiency and developmental delay. Treatment with homocystinuria aims at correct the biochemical abnormalities through disorder management (e.g. surveillance, circumstances to avoid, prevention of primary manifestations, etc.

Homocystinuria-megaloblastic anemia due to defect in cobalamin metabolism, cblG complementation type, also known as methionine synthase deficiency or methylcobalamin deficiency, cblG type, is a rare inborn error of metabolism (IEM) and autosomal recessive disorder of the methionine metabolim pathway. It is caused by a mutation in the MTR gene which encodes the enzyme methionine synthase. This enzyme is responsible for forming L-methionine and tetrahydrofolic acid from homocysteine and 5-methyltetrahydrofolic acid. When the enzyme is mutated, this leads to lower amounts of L-methionine in the cell, as well as increased levels of homocysteine. Methionine synthase deficiency is characterized by an increase in homocysteine levels in the body and excreted in the urine, as well as decreased levels of methionine in the blood. Symptoms include megaloblastic anemia, and can also include developmental delays, seisures and kidney failure. Treatment with vitamin B12, as well as folates and betaine is effective. It is estimated that methionine synthase deficiency affects less than 1 in 1,000,000 individuals.

Homocystinuria-megaloblastic anemia due to defect in cobalamin metabolism, cblG complementation type, also known as methionine synthase deficiency or methylcobalamin deficiency, cblG type, is a rare inborn error of metabolism (IEM) and autosomal recessive disorder of the methionine metabolim pathway. It is caused by a mutation in the MTR gene which encodes the enzyme methionine synthase. This enzyme is responsible for forming L-methionine and tetrahydrofolic acid from homocysteine and 5-methyltetrahydrofolic acid. When the enzyme is mutated, this leads to lower amounts of L-methionine in the cell, as well as increased levels of homocysteine. Methionine synthase deficiency is characterized by an increase in homocysteine levels in the body and excreted in the urine, as well as decreased levels of methionine in the blood. Symptoms include megaloblastic anemia, and can also include developmental delays, seisures and kidney failure. Treatment with vitamin B12, as well as folates and betaine is effective. It is estimated that methionine synthase deficiency affects less than 1 in 1,000,000 individuals.