this disease (hereditary), which is characterized by the excretion of urine, a consequence of the acid and disorder of tyrosine metabolism. The disease is caused by loss of function of the oxidase a consequence, acid.
Alkaptonuria develops due to a mutation of the gene that encodes the synthesis of the oxidase a consequence, acid. The disease is characterized by autosomal-recessive type of inheritance and often affects men.
A consequence acid is an intermediate breakdown product of phenylalanine and tyrosine and is translated in maleylacetoacetate acid, which are formed from acetoacetic and fumaric acid (to enter into other biochemical cycles).
This process because of a defect of the enzyme is inhibited and a consequence acid is converted to benzophenone or alkapton (hinnawy polyphenol) that are excreted by the kidneys. A number of alkapton is deposited in connective tissues, which makes them more brittle and darkening. Most often pigmentation of the ear cartilage and sclera.
Alkaptonuria is transmitted in an autosomal recessive manner (genetically). So, parents with autosomal recessive disease, carriers of the mutation of genes (one copy), but often they have no symptoms.
An early symptom alkaptonuria is the urine of a child, which quickly darkens after standing in air or heating. Later, you may receive
with the complication
. And after 30 years usually appear signs of musculoskeletal lesions of the joints of the lower extremities (large) of the hip or knee, less shoulder joints
- pain of a mechanical nature
- the progress of destructive changes in the cartilage of joints (fast enough)
- excess deposition of consequence of acid in the tendons, ligaments, membranes and tendons, which often lead to calcification and development of inflammatory changes of a local character
- affected the spine
- pain in the lumbar spine, rarely in the thoracic and cervical. X-rays revealed calcification of the intervertebral discs (hallmark alkaptonuria) and changes characteristic of osteoarthritis (common). Possible involvement of major joints (simultaneous) of the spine and its isolated lesions
- in the developed stage of the disease, most patients with alkaptonuria found in the affected tissues of the ears (cartilage). The color of the auricles may be gray or blue
- sometimes changing the color of the skin of the palms, underarms, and nasolabial folds
- often there is pigmentation of the sclera that is associated with the fact that they are deposited deposits a consequence of acid (this characteristic plays an important role in the diagnosis of disease)
- about a fifth of patients with alkaptonuria suffer from changes in the aortic (or mitral) valve, which is characterized by calcification of the annulus, the valves and aorta (ascending). In this case it often requires valve replacement
- calcification of the coronary arteries
- asymptomatic calculous prostatitis.
To diagnose alkaptonuria, doctors use the most effective in this respect, the method is a method of quantitative determination benzobisoxazole and a consequence of acids in the urine. Used for this purpose is liquid chromatography, or enzymatic spectrophotometry. There is a simple method of diagnosis of the disease, which is considered less accurate assessment of urine color after stay in the air for 12-24 hours (the urine becomes brown or black due to oxidation of alkapton). Such changes occur only at alkaline pH of urine, it is necessary to alkalize in acid reaction of urine.
In addition, the presence of pigmentation of the cartilage that normally comes up in arthroscopy of the heart valves (if prosthetic) or the synovial membrane by microscopic examination, can also be diagnosed with alkaptonuria.
Treatment alkaptonuria with hypovitaminosis With is the appointment of ascorbic acid (large doses). In General, the radical treatment of the disease there.