Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0003864 (arthritis)
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Alkaptonuria, a rare autosomal-recessive disorder caused by mutations in the HGD gene and a deficiency of homogentisate 1,2-dioxygenase, is characterized by accumulation of homogentisic acid (HGA), ochronosis, and destruction of connective tissue resulting in joint disease. Certain medications have been reported to cause cutaneous hyperpigmentation resembling that of alkaptonuria. We present 5 such cases. Eighty-eight patients with a possible diagnosis of alkaptonuria were examined at the National Institutes of Health Clinical Center between June 2000 and March 2004. The diagnosis of alkaptonuria was confirmed or ruled out by measurement of HGA in the urine. Five patients with findings consistent with ochronosis, including pigmentary changes of the ear and mild degenerative disease of the spine and large joints, were diagnosed clinically as having alkaptonuria, but the diagnosis was withdrawn based on normal urine HGA levels. All 5 patients were women who had taken minocycline for dermatologic or rheumatologic disorders for extended periods. Minocycline-induced hyperpigmentation should be considered in the differential diagnosis of ochronosis. This could be of increased significance now that minocycline and other tetracyclines have been proposed as therapeutic options for rheumatoid arthritis, bringing a new population of patients with ochronosis and arthritis to medical attention with the potential, but incorrect, diagnosis of alkaptonuria.
Arthritis Rheum 2004 Nov
PMID:Minocycline-induced hyperpigmentation masquerading as alkaptonuria in individuals with joint pain. 1552 43

Alkaptonuria is an autosomal recessive disease with late complications (arthritis and ochronosis). Excretion of alkapton (homogentisic acid) in the urine is due to congenital lack of the enzyme homogentisate 1,2-dioxygenase, which mediates the essential step in the catabolism of phenylalanine and tyrosine. Urine excretion of homogentisic acid is very high, urine turns dark if allowed to stand or is alkalinized (a result of formation of polymerization products of alkapton). The presence of alkapton in urine has high lithogenic effect. We report 71 years old man suffering from alkaptonuria with present severe late complications. In this man black coloured urinary calculus was extracted from the urethra. This calculus was formed of organic amorphous part and crystallized part analyzed by X-ray diffraction and infrared spectroscopy identifying weddelite and whitlockite (1:1), and trace amounts of carbonate apatite.
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PMID:[Formation of the urinary stones in alkaptonuria patients]. 1872 31

Alkaptonuria is a rare disorder of metabolism caused by deficiency of homogentisic acid oxidase enzyme and characterized by triad of homogentisic aciduria (dark urine), relentlessly progressive arthritis and ochronosis. We have documented a case with typical features of alkaptonuria along with intramedullary calcification which has not been reported in the literature before.
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PMID:Alkaptonuria and intramedullary calcification. 1884 13

Alkaptonuria is a rare metabolic disorder characterized by a deficiency of the homogentisic acid oxidase enzyme. The result is accumulation of homogentisic acid in collagenous structures throughout the body, especially in fibrous and cartilaginous tissue. This leads to gradual development of a phenomenon known as ochronosis. Characteristic features of ochronosis are urine darkening, progressive scleral pigmentation, subcutaneous cartilage pigmentation (for example, ear cartilage and nails) and degenerative ochronotic arthropathy resembling osteoarthritis. In addition, cardiovascular and genitourinary systems are also affected. Alkaptonuric ochronosis is particularly interesting because it can be detected based only on clinical signs and medical history. Herein we present a patient with typical signs and symptoms such as darkening of urine, pigmented sclerae, nails and ear cartilage, manifesting arthritis in his fifth decade. Additional clinical examination indicated alkaptonuria, which was unrecognized in childhood.
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PMID:Unrecognized ochronosis--a case report. 1894 7

Alkaptonuria is a rare disease in which the body does not have enough of an enzyme called homogentisic acid oxidase. Osteoarthritis is the most common degenerative joint disease. Ochronotic arthritis which resulting from the deposition of oxidized homogentisic acid within the connective tissues of peripheral joints has clinical feature that resembles those of osteoarthritis, but it has a unique manifestation. We reported a case of a patient of ochronotic arthritis, arthroscopic findings showed large areas of darkly pigmented full-thickness cartilage defects in the right knee, the whole meniscal parenchymatous tissue was also darkly pigmented. Histological investigation proved to be ochronosis.
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PMID:Osteoarthritis? Ochronotic arthritis! A case study and review of the literature. 1938 13

Alkaptonuria (AKU) is a rare autosomal recessive metabolic disorder, characterized by accumulation of homogentisic acid, leading to darkened urine, pigmentation of connective tissue (ochronosis), joint and spine arthritis, and destruction of cardiac valves. AKU is due to mutations in the homogentisate dioxygenase gene (HGD) that converts homogentisic acid to maleylacetoacetic acid in the tyrosine catabolic pathway. Here we report a comprehensive mutation analysis of 93 patients enrolled in our study, as well as an extensive update of all previously published HGD mutations associated with AKU. Within our patient cohort, we identified 52 HGD variants, of which 22 were novel. This yields a total of 91 identified HGD variations associated with AKU to date, including 62 missense, 13 splice site, 10 frameshift, 5 nonsense, and 1 no-stop mutation. Most HGD variants reside in exons 3, 6, 8, and 13. We assessed the potential effect of all missense variations on protein function, using five bioinformatic tools specifically designed for interpretation of missense variants (SIFT, POLYPHEN, PANTHER, PMUT, and SNAP). We also analyzed the potential effect of splice-site variants using two different tools (BDGP and NetGene2). This study provides valuable resources for molecular analysis of alkaptonuria and expands our knowledge of the molecular basis of this disease.
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PMID:Mutation spectrum of homogentisic acid oxidase (HGD) in alkaptonuria. 1986 42

Endogenous ochronosis or alkaptonuria is a rare, autosomal recessive disease of tyrosine metabolism that is caused by a deficiency of the enzyme homogentisic acid oxidase. The disease results in the accumulation and deposition of homogentisic acid in the cartilage, eyelids, forehead, cheeks, axillae, genital region, buccal mucosa, larynx, tympanic membranes, and tendons. The disease generally presents in adults with arthritis and skin abnormalities; occasionally, involvement of other organs may be seen. A 49-year-old man was referred to our clinic with verrucous lesions on his hands. On physical examination, caviar-like ochronotic papules were found around his eyes and the helix cartilage of his ears, and on the dorsa of both hands. There were brown macules on the sclera (Osler's sign). The patient had arthritis and nephrolithiasis, and a sample of his urine darkened upon standing. Histopathological examination showed deposition of ochronotic pigment. High-dose ascorbic acid was given, and the patient showed improvement on follow-up examination 6 months later.
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PMID:Endogenous ochronosis. 2005 50

Alkaptonuria is a rare autosomal recessive metabolic disorder characterized by a deficiency of homogentisate 1,2-dioxygenase (HGO) in the liver. This results in excretion of large quantities of homogentisic acid (HGA) (also called alkapton) in the urine and a slowly progressive deposition of homogentisic acid and its oxidative product in connective tissues. Clinical characteristic features of alkaptonuria are darkening of urine, bluish-dark pigmentation of connective tissues (ochronosis) and arthritis of large joints and spine. Cardiovascular and genitourinary systems may also be affected. In this report, we present the initial results of screening family members with history of alkaptonuria in southern region of Jordan. We present 9 cases of alkaptonuria (two males and seven females) in one Jordanian family. The history, signs and symptoms, diagnostic techniques and treatment options of alkaptonuria are reviewed in this article.
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PMID:Nine cases of Alkaptonuria in one family in southern Jordan. 2112 75

Alkaptonuria is a rare hereditary metabolic disease of autosomal recessive inheritance, resulting from deficiency of the enzyme homogentisic acid oxidase. The term "alkaptonuria" was first used in 1859 by Boedeker to describe a patient's urinary reducing compound, and in 1866, Virchow coined the term "ochronosis" due to typical yellow pigmentation. Deposition of this pigment in articular cartilage leads to ochronotic arthropathy, the most incapacitating complication of alkaptonuria. We report a rare case of shoulder ochronotic arthritis, treated with total shoulder arthroplasty, achieving a successful long-term clinical and radiological outcomes.
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PMID:Shoulder arthroplasty in alkaptonuric arthropathy: a clinical case report and literature review. 2244 74

Alkaptonuria, a metabolic disorder characterized by a triad of homogentisic aciduria, arthritis and ochronosis is one of the first conditions in the charter of group of inborn errors of metabolism proposed to have Mendelian recessive inheritance. It is due to the deficiency of the enzyme homogentisic acid oxidase which catalyzes the conversion of homogentisic acid to maleylacetoacetic acid in the catabolism of tyrosine. Homogentisic acid thus accumulates in cells and body fluids and its oxidized polymers bind to collagen, leading to progressive deposition of grey to bluish black pigment resulting in degenerative changes in cartilage, intervertebral disc and other connective tissues, leading to arthritis which is the only disabling effect in an affected older individual. However the diagnosis can be made in neonates when blackish stain is noticed in an unwashed diaper. Alkaptonuria is treated symptomatically, surgical intervention necessitates in advanced stages, treatment with ascorbic acid (Vitamin C) and dietary restrictions of food containing phenylalanine and tyrosine have proved to be successful in alleviating the symptoms.
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PMID:Alkaptonuric ochronosis: Report of a case and brief review. 2310 6


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