alkaptonuria


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alkaptonuria

 [al-kap″to-nu´re-ah]
an autosomal recessive aminoacidopathy characterized by accumulation of homogentisic acid. It is manifested by elevated concentrations of homogentisic acid in the urine (which darkens on standing or with alkalinization), a peculiar discoloration of body tissues known as ochronosis, and arthritis.

al·cap·ton·u·ri·a

, alkaptonuria (al-kap-ton-yū'rē-ă), [MIM*203500]
Excretion of homogentisic acid (alkapton) in the urine resulting from congenital lack of the enzyme homogentisate 1,2-dioxygenase, which mediates an essential step in the catabolism of phenylalanine and tyrosine; urine turns dark if it is allowed to stand or is alkalinized (a result of formation of polymerization products of homogentisic acid); frequently occurs throughout relatively long periods or may appear at irregular intervals; arthritis and ochronosis are late complications; autosomal recessive inheritance; caused by mutation in the homogentisate 1,2-dioxygenase gene (HGD) on chromosome 3q.
[alkapton + G. ouron, urine]

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

alkaptonuria

or

alcaptonuria

(ăl-kăp′tə-no͝or′ē-ə)
n.
An inherited disorder that affects phenylalanine and tyrosine metabolism and leads to the excretion of homogentisic acid in the urine.

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 phenylalanine. 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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Alkaptonuria

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.

al·cap·to·nu·ri·a

, alkaptonuria (al-kap'tŏ-nyūr'ē-ă)
Excretion of homogentisic acid (alkapton) in the urine due to congenital lack of the enzyme homogentisate 1,2-dioxygenase; urine turns dark if allowed to stand; may recur and subside at irregular intervals; arthritis and ochronosis are late complications.
[alkapton + G. ouron, urine]

alkaptonuria

A genetic disease in which a gene mutation on chromosome 3 results in a defective enzyme that leads to the accumulation of a coloured polymer molecule homogentisic acid. This binds to the COLLAGEN of cartilage, making it brittle and easily worn away. The result is a form of OSTEOARTHRITIS. In alkaptonuria, the urine turns black on exposure to light or alkali.

alkaptonuria

see GARROD,A.E.

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.

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.
References in periodicals archive ?
Alkaptonuria causes progressive ochronotic arthropathy of the large weightbearing joints (knees, hips, shoulders, vertebrae).
Homozygosity mapping of the gene for alkaptonuria to chromosome 3q2.
The announcement of the Liverpool centre comes 110 years after alkaptonuria was first discovered by Sir Archibald Garrod.
His daughters Natalie, 16, and Laura, 11, have not inherited alkaptonuria, but both carry the faulty gene and could pass it to their children.
Now he receives dozens of em ails from patients with alkaptonuria and doctors from around the world.
Homogentisate 1,2 dioxygenase is expressed in human osteoarticular cells: implications in alkaptonuria.
Alkaptonuria is a rare metabolic disorder in the phenylalanine and tyrosine catabolic pathway which is characterized by the excessive excretion of homogentisic acid in the urine, ochronosis, and debilitating arthritis of the spine and large joints.
Teams will work on varied challenges, including: a new 'bioartificial' liver support system to treat acute liver failure; powerful data processing operations to develop novel diagnostic tools, biomarkers and screening strategies for therapeutic agents against rare kidney diseases; and the clinical development of a drug to treat alkaptonuria, a genetic disorder which leads to a severe and early-onset form of arthritis, heart disease and disability for which there is currently no effective treatment.
In total, more than $500,000 worth of research services will be awarded to study 26 different rare diseases, ranging from Alkaptonuria to X-linked intellectual disability (XLID).
He was eventually diagnosed with black bone disease, or alkaptonuria, commonly referred to as AKU.
Researchers have identified more than 100 new cases of the disease, called alkaptonuria (AKU) in a small community in Vellore, India, bringing the total number of patients there to 130.
Donations can be made in lieu of flowers, in aid of the Alkaptonuria (AKU) Society c/o J Bardgett & Sons, 571 Westgate Road, Newcastle upon Tyne, NE4 9PQ.