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Alkaptonuria is an autosomal recessive inborn error of metabolism of the aromatic amino acids. Deficiency of the homogentisate1,2-dioxygenase leads to an increased blood and urinary concentration of homogentisc acid resulting in a slow accumulation of its oxidation products in the connective tissues (ochronosis). The most common clinical manifestation of ochronosis is arthropathy whereas cardiac involvement is very infrequent. We report the case of a patient with ochronotic involvement of the aortic valve who underwent a valve replacement. Some aspects of pathogenesis, and treatment are discussed.

Alkaptonuria is a rare inherited disorder of tyrosine metabolism, which results in deposition of homogentisic acid in the connective tissues. The accumulation of homogentisic acid in connective tissue causes the syndrome known as ochronosis, which is typically manifested by skin pigmentation, degenerative arthropathy and discolouration of urine. Cardiovascular involvement is a much less common complication of alkaptonuria but poses a greater risk to the patient's health. We present the case of a 65 year-old man with aortic stenosis and a previous diagnosis of alkaptonuria who underwent successful aortic valve replacement with a mechanical prosthesis., (Crown Copyright © 2013. Published by Elsevier B.V. All rights reserved.)