homocystinuria


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homocystinuria

 [ho″mo-sis″tin-u´re-ah]
an inborn error of metabolism of sulfur amino acids due to lack of the enzyme cystathionine synthase; it is characterized by homocystine in the urine and by mental retardation, hepatomegaly, ectopia lentis (displacement of the lens), and cardiovascular and skeletal disorders.

ho·mo·cys·ti·nu·ri·a

(hō'mō-sis'ti-nyū'rē-ă), [MIM*236200]
A metabolic disorder characterized by sparse blond hair, long limbs, pectus excavatum, dislocation of lens, failure to thrive, mental retardation, psychiatric disturbances, and thromboembolic episodes; some patients have alleviation of symptoms with pyridoxine whereas others are not responsive; associated with increased urinary excretion of homocystine and methionine. Autosomal recessive inheritance, but carriers have an increased risk of occlusive vascular disease; caused by mutation in the cysthathione beta-synthase gene (CBS) on chromosome 21q. In addition, there are seven other causes of homocystinuria: defect in vitamin B12 metabolism [MIM*277400]; deficiency of N-methylene-tetrahydrofolate reductase [MIM*236250]; selective intestinal malabsorption of vitamin B12 [MIM*261100]; vitamin B12 responsive homocystinuria, cblE type [MIM*236270]; methylcobalamin deficiency, cblG type [MIM*250940], vitamin B12 metabolic defect type 2 [MIM*277410]; and transcobalamin II deficiency [MIM*275350].

homocystinuria

/ho·mo·cys·tin·uria/ (-sis″tin-u´re-ah) excessive homocystine in the urine, having various causes, some genetic; symptoms include developmental delay, failure to thrive, neurological abnormalities, and others depending on the cause. Sometimes the term refers specifically to the disorder due to lack of the enzyme cystathionine β-synthase.

homocystinuria

(hō′mə-sĭs′tə-no͝or′ē-ə)
n.
Any of several genetic disorders of amino acid metabolism that result in elevated levels of homocystine in the urine and are characterized by varied symptoms including dislocation of the crystalline lens of the eye, cardiovascular and skeletal deformities, and intellectual disability.

homocystinuria

[hō′mōsis′tinoo͡r′ē·ə]
Etymology: Gk, homos + (cystine); Gk, ouron, urine
a rare biochemical abnormality characterized by the abnormal presence of homocystine, an amino acid, in the blood and urine, which is caused by any of several enzyme deficiencies in the metabolic pathway of methionine to cystine. The disease is inherited as an autosomal-recessive trait. Its clinical signs are similar to those of Marfan's syndrome, including mental retardation, osteoporosis leading to skeletal abnormalities, dislocated lenses, and thromboembolism. Treatment may include a diet low in methionine and supplementation with large doses of vitamin B6. Long-term results of treatment are not available. homocystinuric, adj.
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Homocystinuria: lens dislocation

homocystinuria

Metabolic disease An AR condition due to a defect of cystathionine β—synthase , characterized by ↑ (> 300 µmol/L) homocysteine in serum Clinical Overgrowth of long bones, mental retardation, osteoporosis, ectopia lentis, failure to thrive, sparse blond hair, genu valgum, thromboembolism, fatty liver; most die before age 30 of arterial and venous occlusive disease; lesser ↑ of homocysteine is seen in heterozygotes, in those with ↓ folic acid, vitamin B12, in renal failure and after heart transplants Lab ↑ homocysteine in urine Management Pyridoxine or vitamin B6.

homocystinuria

The abnormal presence of homocystine in the urine. This may be caused by vitamin B12 deficiency, a B12 metabolic defect, drugs or urinary infection but is usually due to an autosomal recessive enzyme-defect disorder. The hereditary form features sparse blond hair, OSTEOPOROSIS with overgrowth of long bones, a hollowed chest, dislocation of the lenses of the eyes and mental retardation.

homocystinuria

An autosomal recessive inherited disorder caused by a cystathionine beta synthase deficiency, which leads to an accumulation of the amino acid methionine and homocysteine. The first signs are ocular; a dislocated lens which may cause diplopia or glaucoma, myopia and occasionally retinal detachment. Systemic signs are blond hair, intellectual impairment and some of the features of Marfan's syndrome (e.g. tall, thin build).

ho·mo·cys·ti·nu·ri·a

(hō'mō-sis'ti-nyū'rē-ă) [MIM*236200]
Metabolic disorder characterized by sparse blond hair, long limbs, pectus excavatum, dislocation of lens, failure to thrive, mental retardation, psychiatric disturbances, and thromboembolic episodes.
References in periodicals archive ?
Tawfeg Ben-Omran,who is also a Senior Consultant, Pediatrics at HMC, says early detection of rare diseases like Homocystinuria helps eliminate potential complications and ultimately improve long-term health outcomes for patients.
Homocystinuria is the term used for several rare genetic disorders (diseases passed down through families) that cause levels of homocysteine to build up in blood and urine.
Mutation spectrum of MMACHC in Chinese patients with combined methylmalonic aciduria and homocystinuria.
Methylmalonic aciduria and homocystinuria type C protein (MMACHC) may be involved in GSH-dependent MS reactivation.
Comment: Individuals with the rare genetic disease homocystinuria have markedly elevated plasma homocysteine levels and develop osteoporosis at an early age.
Late-onset combined homocystinuria and methylmalonic aciduria (cblC) and neuropsychiatric disturbance.
tHcy is used as a marker for vitamin deficiency, cardiovascular diseases, type 2 diabetes, homocystinuria and other diseases.
Homocystinuria is an autosomal recessive condition affecting the metabolism of the amino acid, methionine, which in turn leads to a build-up of the amino acid homocysteine in blood and urine.
Cystathionine beta-synthase mutations in homocystinuria.
The aforementioned risk factors, including also genetic predisposition to low HDL-ch (<35 mg/dl), as well as free radical oxidation of LDL-ch and lipoprotein Lp(a) fractions, hyperbetalipoproteinemia, homocystinuria, oxidative modification of LDL-ch, together with the so-called uninhibited stimulated inflammatory response of leukocytes/endothelial cells, induce the cascade of atherosclerotic processes [2,3,10,23-25].
A syndrome of methylmalonic aciduria, homocystinuria, megaloblastic anemia and neurologic abnormalities in a vitamin [B.
Catatonia was first described by Karl Kahlbaum in 1874 and has as an aetiology neurological disorders (encephalopaties, tumours, degenerative, central pontine myelinolysis, locked-in syndrome), psychiatry (hysteria, neuroleptic malignant syndrome, schizophrenia, psychosis, drug withdrawl), infectious diseases (AIDS, malaria, neurosyphilis), metabolic ones (Addison's, diabetic ketoacidosis, hepatic or renal failure, poisoning), but also inherited neurometabolic disorders such as homocystinuria, coproporphyria, Tay-Sachs disease.