Alkaptonuric ochronosis: a clinical study from Ardabil, Iran

Abstract

Objective: Ochronosis is a term used to describe pigment deposition that occurs in the connective tissues of patients with alkaptonuria, an autosomal recessive disorder that results from a deficiency of homogentisic acid oxidase. Brown or blue-gray discoloration of the skin may be seen on the axillary and inguinal areas, face, palms or soles. In addition, blue-black discoloration can be apparent on skin overlying cartilage in which the pigment is deposited, such as the ears. The sclerae are also typically involved. The cheapest screening test to perform prior to expensive lab tests is the urine oxidation test: having it standing in light for a period of 24 h when suspicion has risen.

Methods: Retrospective analysis of patients with ochronotic arthropathy seen between September 2011 to September 2013 was carried out.

Results: Seven patients (four male, three female) with ochronotic arthropathy were seen, their mean age was 46.1 years. All patients had bluish-black pigmentations of the ear cartilage and sclera. Spondylosis was seen in all, whereas peripheral arthritis was present in five patients. Moderate aortic insufficiency and calcification of the aortic valve was detected in one male patient. Urine screening for homogentisic acid was positive in all seven patients.

Conclusion: Alkaptonuria is a rare autosomal recessive disorder of the metabolism caused by deficiency of homogentisic acid oxidase. It is suggested that more widespread screening should be undertaken in order to assess the true incidence of the disorder.

Keywords: alkaptonuria; homogentisic acid; ochronosis; spondylosis.