alkaptonuria (redirected from Black Urine Disease)

alkaptonuria /al·kap·ton·uria/ (al-kap″to-nu´re-ah) an autosomal recessive aminoacidopathy with accumulation of homogentisic acid in urine (causing urine to darken on standing), ochronosis, and arthritis.alkaptonu´ric

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al·kap·to·nu·ri·a or al·cap·to·nu·ri·a (l-kpt-nr-)

n.

An inherited disorder that affects phenylalanine and tyrosine metabolism and leads to the excretion of homogentisic acid in the urine. Also called homogentisuria.

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alkaptonuria

[alkap′tōnoo͡r′ē·ə]

Etymology: Ar, al + galiy + Gk, haptein to possess, ouron urine

a rare inherited disorder marked by the excretion of large amounts of homogentisic acid in the urine, which is the result of the incomplete metabolism of the amino acids tyrosine and phenylal. The presence of the acid is indicated by darkening of urine when exposed to air or by brown or blue discoloration of the ears or eyes. Other indications are restricted joint mobility, kidney stones, and vascular hypertension. See also ochronosis. alkaptonuric, adj.

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alcaptonuria, alkaptonuria

excretion in the urine of homogentisic acid and its oxidation products as a result of a genetic disorder of phenylalanine-tyrosine metabolism in humans and orang-utans.

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alkaptonuria 

A rare, hereditary, metabolic disorder characterized by dark urine. It is caused by mutation in the homogentisate 1, 2-dioxygenase gene (HGD), which produces an error in the metabolism of the amino acids tyrosine and phenylalanine, which normally break down by oxidation to homogentisic acid. However, in this condition homogentisic acid is not broken down but stored in tissues, especially cartilage, which it turns bluish-black, and excreted in the urine. Ocular signs are pigmentation of the sclera, most markedly near the insertions of the recti muscles, and of the cornea and conjunctiva.

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alkaptonuria

Black pain disease, black urine disease, alcaptonuria, alcaptonuric ochronosis An AR defect in tyrosine and phenylalanine metabolism, more common in ♂, due to homogentisic acid oxidase–HAO deficiency; metabolic pathway of phenylalanine and tyrosine → ring opening of homogentisic acid → malylacetoacetic acid; alkaptonuria is first recognized by the mother who cannot clean the children's diaper as the urine oxidizes to a pitch black color upon exposure to air Clinical Arthritis due to homogentisic acid deposition in cartilage, tendons, as well as in the sclera, viscera, skin; when severe, pigment deposition can compromise cardiac, renal, or pulmonary function, and spill into the urine as a melanin-like substance. Cf Blue diaper syndrome.