alkaptonuria


alkaptonuria
/al kap'teuh noor"ee euh, -nyoor"-/, n. Pathol.
excessive excretion of homogentisic acid in the urine, caused by a hereditary abnormality of the metabolism of tyrosine and phenylalanine.
[1885-90; ALKAPTON + -URIA]

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      rather rare (one in 200,000 births) inherited disorder of protein metabolism characterized by an inability of the body to metabolize the amino acids tyrosine and phenylalanine. In the normal metabolic pathway of tyrosine, homogentisic acid is converted to maleylacetoacetate in the liver by the enzyme homogentisate 1,2-dioxygenase. This enzyme is not active in individuals who have alkaptonuria. Except for a blackening of the urine due to the buildup and oxidation of homogentisic acid, this disorder has no clinical manifestations until the affected person is in his twenties or thirties, when deposits of ochre pigments begin to appear in various fibrous connective tissues of the body. The pigment, bound to collagen fibres in the deeper layers of joint cartilage and intervertebral disks (the fibrous pads between adjacent bones of the spine), causes these tissues to lose their normal resiliency and become brittle. The erosion of the abnormal cartilage leads to a progressive degenerative disease of the joints, which usually becomes manifest by the fourth decade of life. Usually, the intervertebral disks become thinned and calcified first, and later the knees, shoulders, and hips are affected.

      Alkaptonuria is compatible with normal life expectancy. In some cases arteriosclerosis has been described; however, it is not known whether this is a manifestation of the disease or coincidental. No effective treatment is available for the underlying metabolic disorder.

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Universalium. 2010.

Look at other dictionaries:

  • alkaptonuria — alkaptonuria. См. алкаптонурия. (Источник: «Англо русский толковый словарь генетических терминов». Арефьев В.А., Лисовенко Л.А., Москва: Изд во ВНИРО, 1995 г.) …   Молекулярная биология и генетика. Толковый словарь.

  • Alkaptonuria — Infobox Disease Name = PAGENAME Caption = Homogentisic acid Width = 180 DiseasesDB = 409 ICD10 = ICD10|E|70|2|e|70 ICD9 = ICD9|270.2 ICDO = OMIM = 203500 MedlinePlus = eMedicineSubj = ped eMedicineTopic = 64 MeshID = D000474 Alkaptonuria (black… …   Wikipedia

  • Alkaptonuria — aminorūgščių statusas T sritis embriologija atitikmenys: lot. Acidi aminoici; Alkaptonuria ryšiai: platesnis terminas – medžiagų apykaitos nepakankamumas sinonimas – alkaptonurija …   Medicininės histologijos ir embriologijos vardynas

  • alkaptonuria — Congenital absence of homogentisic acid oxidase, an enzyme that breaks down tyrosine and phenylalanine. Accumulation of homogentisic acid in homozygotes causes brown pigmentation of skin and eyes and damage to joints; urine blackens on standing …   Dictionary of molecular biology

  • alkaptonuria — noun A rare inherited genetic disorder of phenylalanine and tyrosine metabolism, causing the accumulation and eventual excretion of alkapton …   Wiktionary

  • alkaptonuria — al·kap·ton·uria or al·cap·ton·uria (.)al .kap tə n(y)u̇rē ə n a rare recessive metabolic anomaly in humans marked by inability to complete the degradation of tyrosine and phenylalanine resulting in the presence of alkapton in the urine * * * n.… …   Medical dictionary

  • alkaptonuria — n. disease characterized by alkapton in the urine …   English contemporary dictionary

  • alkaptonuria — al·kap·ton·u·ria …   English syllables

  • alkaptonuria — n.; see alcaptonuria …   The new mediacal dictionary

  • alkaptonuria — /ælˌkæptəˈnjuriə/ (say al.kaptuh nyoohreeuh) noun a congenital malfunctioning of certain biochemical processes in the body affecting proteins, which results in severe mental impairment …   Australian English dictionary


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