Intervertebral discs calcification due to ochronosis Patients with<unk>  are asymptomatic as children or young adults, but their urine may turn brown or even inky black if collected and left exposed to open air. Pigmentation may be noted in the cartilage of the ear and other cartilage, and the sclera and corneal limbus of the eye. After the age of 30, people begin to develop pain in the weight-bearing joints of the spine, hips, and knees. The pain can be severe to the point that interferes with activities of daily living and may affect the ability to work. Joint-replacement surgery (hip and shoulder) is often necessary at a relatively young age. In the longer term, the involvement of the spinal joints leads to reduced movement of the rib cage and can affect breathing. Bone mineral density may be affected, increasing the risk of bone fractures, and rupture of tendons and muscles may occur. Valvular heart disease, mainly calcification and regurgitation of the aortic and mitral valves, may occur, and in severe and progressive cases, valve replacement may be necessary. Irregularities in the heart rhythm and heart failure affect a significant proportion of people with<unk>  (40% and 10%, respectively). Hearing loss affects 40% of people. Also, a propensity to developing kidney stones exists, and eventually also gallstones and stones in the prostate and salivary glands (sialolithiasis) can occur.
Alkaptonuria
Hawkinsinuria
Orotic aciduria
Cystathioninuria
Aspartylglucosaminuria
Homocystinuria
Urocanic aciduria
Glycosuria