Alkaptonuria, also known as Ochronosis, is an inherited disorder caused by the lack of an enzyme called homogentisate 1,2-dioxygenase (HGO). It is characterized by the accumulation of homogentisic acid (HGA) in the body, leading to the classic “ochronotic” phenotype, which includes dark urine, grayish pigmentation of the skin and cartilage, and arthropathy.
The findings of alkaptonuria typically appear in the early years of life. The affected individual will have dark urine that becomes darker over time, indicating the accumulation of homogentisic acid. The skin of the individual may become grayish in color due to the deposition of the HGA pigment in the skin, and the cartilage in the ear and nose may become ochre-colored. In addition, the individual may experience joint pain and stiffness due to the deposition of HGA in the joints, leading to arthropathy.
In terms of diagnosis, the presence of dark urine and the ochre-colored cartilage on physical examination, along with a family history of alkaptonuria, are indicative of this condition. Furthermore, urine and blood tests can be used to measure the levels of homogentisic acid and confirm the diagnosis.
In terms of treatment, alkaptonuria cannot be cured, but the symptoms can be managed with dietary modifications and the use of medications such as acetaminophen and NSAIDs. Surgery can also be used to remove the ochre-colored cartilage. Additionally, the use of antioxidants, such as vitamin C, may help reduce the damage caused by the accumulation of homogentisic acid. Finally, genetic counseling is recommended for affected individuals and their families, as the condition is inherited in an autosomal recessive pattern.