homocystinuria


Also found in: Encyclopedia, Wikipedia.

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

(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

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 ?
Determination of total homocysteine in dried blood spots using high performance liquid chromatography for homocystinuria newborn screening.
The target populations include patients, in particular children and young adults, with symptoms of homocystinuria, including thromboembolism, lens dislocation, progressive myopia, osteoporosis, marfan-like appearance, unexplained mental retardation, psychiatric disorders, or megaloblastic anemia, as well as siblings or children of patients with homocystinuria.
Some patients with schizophrenia or with the rare genetic disease, homocystinuria, seem to need vitamin B6 in dosages well above 500 mg per day in order to obtain the maximum benefit.
Psychiatric manifestations of homocystinuria due to cystathionine beta-synthase deficiency: prevalence, natural history, and relationship to neurologic impairment and vitamin B6-responsiveness.
Hyperhomocysteinemia May occur isolated, but is also a feature of inherited metabolic disorders, including homocystinuria, due to mutation in the CBS gene, and N(5,10)-methylenetetrahydrofolate reductase deficiency, caused by mutation in the MTHFR gene (607093); homocysteinemia/ homocystinuria and megaloblastic anemia can result from defects in vitamin B12 (cobalamin; cbl) metabolism.
Initially her project, titled as Philippine NBS Project, was testing only six metabolic conditions, such as hypothyroidism, congenital adrenal hyperplasia, galactosemia, phenylketonuria, homocystinuria and glucose-6-phosphate dehydorgenase deficiency.
Gallstones in a patient with homocystinuria. Indian J Gastroenterol 2009;28(4):157-8.
A syndrome of methylmalonic aciduria, homocystinuria, megaloblastic anemia and neurologic abnormalities in a vitamin B12-deficient breast-fed infant of a strict vegetarian.
Hamad Medical Corporation's (HMC) Head of Clinical and Metabolic Genetics says early detection is the key to successfully managing rare conditions like Homocystinuria, a serious genetic disease characterised by long-term complications.
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.
Typical examples include phenylketonuria (PKU), maple syrup urine disease (MSUD), or classical homocystinuria (HCU, cystathionine-[beta]-synthase deficiency).
One case report of homocystinuria with moyamoya was also described in the literature [5].