Browsing Pathways

Gout, also called Kelley-Seegmiller syndrome, is a condition that is hereditary and causes an excess in the production of uric acid in the body. It is caused by a deficiency of the enzyme hypoxanthine-guanine phosphoribosyltransferase. When working properly, this enzyme works to restore purines. These purines are salvaged from degraded DNA and are used towards purine synthesis. When uric acid builds up as it is being overproduced, needle-like crystals are formed and can provoke sudden attacks of pain in the joints, the big toe and in other places around the body. Unlike Lesch-Nyhan syndrome, this condition does not present neurological conditions and can be treated with medication.

Guanidinoacetate Methyltransferase Deficiency (Creatine-Deficiency-Syndrome) is a rare autosomal recessive disease caused by a mutation in the GAMT gene which codes for guanidinoacetate N-methyltransferase. A deficiency in this enzyme results in accumulation of 3-methylglutaconic acid in urine; guanidoacetic acid in urine and serum. Decreased concentrations of creatine are found in serum and urine; and creatinine in plasma, spinal fluid, and urine. Symptoms, which present at birth, include failure to thrive, mental and motor retardation, hyoptonia, and seizures. Treatment includes arginine-restricted diet, sodium benzoate, and L-ornithine hydrochlorate.

Hawkinsinuria (4-Hydroxyphenylpyruvate Hydroxylase Deficiency) is an autosomal dominant disease caused by a mutation in the HPD gene which codes for 4-hydroxyphenylpyruvate dioxygenase. A deficiency in this enzyme results in accumulation of hawkinsin in urine and plasma; cis-4-hydroxycyclohexylacetic acid, trans-4-hydroxycyclohexylaceid, vanillactic acid, 4-hydroxyphenylpyruvic acid, pyroglutamic acid in urine; and L-tyrosine in plasma. Symptoms include ketosis, metabolic acidosis, swimming-pool odor, and mental retardation. Treatment includes a low-protein diet and vitamin C.

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.

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.

Zellweger syndrome, also known as cerebrohepatorenal syndrome, is an autosomal recessive peroxisome biogenesis disorder that is part of the family of Zellweger spectrum disorders. It is caused by a defect in one of 12 or more of the PEX genes (PEX1, 2, 3, 5, 6, 10, 12, 13, 14, 16, 19 and 26) that produce proteins called peroxins. Peroxins are used in the formation of peroxisomes, and can be involved in recognition of proteins targeted for the peroxisome, as well as their transport into the peroxisome. Peroxisomes typically break down both very long chain and branched fatty acids, but if they aren't present, these fatty acids build up in the blood and body, harming organs such as the brain and liver. Additionally, due to the fact that some processes, such as plasmalogen biosynthesis, occur in or using peroxisomes, and can lead to deficiencies in plasmalogens. These are important in brain and lung function, leading to other symptoms. Zellweger syndrome is characterized by an increase in levels of very long chain fatty acids in the blood plasma, as well as more visible physical symptoms, such as an abnormally large or small head at birth, characteristic facial features and poor muscle tone, which can lead to an inability of infants to feed. Other symptoms include an enlarged liver, skeletal abnormalities and low CNS function. Infants very rarely live longer than one year, and the only treatment is for symptoms the patient is experiencing, not for the syndrome itself.

Hyperinsulinism-hyperammonemia syndrome (HHS; Glutamate dehydrogenase 1; GLUD1), an inherited condition, is caused by a defect in the GLUD1 gene which codes for mitochondrial glutamate dehydrogenase 1. It is a mitochondrial matrix enzyme, with a key role in the nitrogen and glutamate (Glu) metabolism and the energy homeostasis. An excessive activity of this enzyme results in high insulin and ammonia levels in blood; decrease level of glucose in blood. Symptoms and signs include shakiness, weakness, seizure, rapid pulse and confusion. Maintain normoglycemia is essencial to prevent neurologic damage. Some medications can be used to suppress insulin secretion.

The rare genetic disorder, Xanthinuria (also referred to as xanthine oxidase deficiency) results from a deficiency of the enzyme xanthine oxidase. This enzyme deficiency causes the accumulation of: xanthine in the plasma, uric acid in serum or hypoxanthine, uric acid and xanthine in the urine. The disorder has symptoms including arthralgia, hematuria, mental retardation, stomatisis, and urolithiasis.

Hypermethioninemia is a rare error of metabolism (IEM) which arises when there is a disfunction in the gene called AHCY. This gene is responsible for Adenosylhomocysteinase, an enzyme which takes S-adenosyl homocysteine as input, and produces homocysteine as its output. This outputted compound through the its respective pathway may be turned back into cysteine methionine. A dysfunctional defect Adenosylhomocysteinase can lead to the build of of these two compounds in the blood. Of particular interest is that individuals who are affected by hypermethioninemia present a wide spectrum of symptoms. This ranges anywhere from the complete absence of symptoms, to mental retardation, muscle weakness, liver problems, and unusual facial features.