from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. A rare inherited genetic disorder of phenylalanine and tyrosine metabolism, causing the accumulation and eventual excretion of alkapton.
from The Century Dictionary and Cyclopedia
- n. The presence of alkapton in the urine when voided: a rare metabolic anomaly. Also alcaptonuria.
from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
- n. a rare recessive metabolic anomaly marked by ochronosis and the presence of alkapton in the urine
Smith, now 46, was born with alkaptonuria, a rare genetic disorder that led to severe arthritis in his early 40s.
In urine, as in tissues, HGA oxidizes to benzoquinones, which in turn form melanin-like polymers. 1 Accumulation of HGA and its metabolites in tissues causes ochronosis, with darkening of cartilaginous tissues and bone, arthritis and joint destruction, formation of renal stones and deterioration of cardiac valves. 2Clinically, alkaptonuria resembles ankylosing spondylitis in its predilection to damage to the spine and large joints but differs in sparing the sacroiliac joint.
Large blisters, like these, are called bullae alkaptonuria, ochronosis X-ray lower lumbo-sacral spine and sacro-iliac joints showing normal sacro-iliac joints and calcification of intervertebral discs alkaptonuria, ochronosis grossly calcified intervertebal discs alkaptonuria, ochronosis early ankylosis of spine alkaptonuria, ochronosis bluish spots on his sclera alkaptonuria, ochronosis Bluish discoloration os ear cartillage hypertrophic osteoarthropathy Note diffuse periosteal new bone formation of the distal radius and ulna.
The estimated current incidence of alkaptonuria is 1 case in 250,000 to 1 million live births. 1 CASE REPORTA 35 years old male came to our clinic with joint pains for 2 years starting from right wrist joint, later moving to right knee, right ankle and then to left wrist, knee and ankle.
We present the case of a 68-year-old Caucasian man with alkaptonuria-associated degenerative valvular defects with aortic, mitral and tricuspid valve insufficiency.
Pigmentation of the sclera and ear cartilage occurred only after the age of 30 years and is extremely variable in severity. 3 Tendon and ligament ruptures occur with minimal provocation, and kidney stones probably form because of the extremely high levels of urinary HGA excretion (renal clearance rates of 400 to 500 ml per minute). 4�Diagnosis depends on typical radiological findings and demonstration of reducing substance-homogentisic acid in the urine. 4 Several therapeutic approaches have been used in patients with alkaptonuria. 5 High-dose vitamin C decreases urinary benzoquinone acetic acid but has no effect on HGA excretion and no credible studies have shown that treatment with vitamin C is clinically effective. 6 The main therapeutic step is direct pharmacologic reduction of HGA production with nitisinone, a triketone herbicide that inhibits