A Case of Alkaptonuria Diagnosed in Late Adulthood

Background: Alkaptonuria (AKU), also known as black urine disease, ochronosis as well, is a rare Mendelian autosomal recessive disorder, located on chromosome 3q21-q23, caused by deficiency of the homogentisate 1,2 dioxygenase (HGO), an enzyme which normally catalyses the conversion of homogentisic acid (HGA) into maleylacetoacetic acid, in the tyrosine degradation pathway. It results in accumulation and deposition of homogentisic acid in cartilage, eyelids, forehead, hand, axillae, genital regions, nail beds, buccal mucosa, larynx, tympanic eardrum, and the tendons. This condition leads to a severe and crippling arthropathy. We present a case of AKU in a 53 year old woman in Mashhad, Iran.

Case Presentation: In this paper, we report a case of 53-year-old woman who presented with AKU and ochronotic pigment deposited in articular cartilage, sclera, cartilage of the ear, hands and degenerative arthropathy in Ghaem Hospital, in Mashhad, Iran. The features include arthritis of the spine and in larger peripheral joints. The problem began about 9 years ago with a history of darkening of urine and discoloration of sclera, ears and hands. In imaging studies, there were degenerative changes in spine. She also underwent hand biopsy which showed Ochronotic pigmentation.

Conclusion: This case report that shows AKU must be considered in the evaluation of low back pain of patients’ bluish discoloration, ochronotic pigment deposited in cartilage tissues, sclera and hands. Therapeutic options include protein restriction, administration of high dose vitamin C.