Ochronosis is the bluish-black or grey-blue discoloration of the skin, especially the ear cartilage, the ocular (eye) tissue, and other body locations. It can occurs in individuals with alkaptonuria, an inherited metabolic disorder; or because of exposure to various substances. Ochronosis associated with alkaptonuria is caused by a genetic change in the HGD gene, which results in the accumulation and deposition of homogentisic acid (HGA) in cartilage. The affected tissue becomes weak and brittle with time, leading to chronic inflammation, joint pain, and osteoarthritis. Alkaptonuria is inherited in an autosomal recessive manner. Alkaptonuria can be diagnosed based on the symptoms, laboratory testing, and genetic testing. When Ochronosis is due to exposure to substances (called exogenous Ochronosis), the condition is not inherited. Exogenous Ochronosis is associated with malarial drugs, skin-lightening creams and over-exposure to the sun. Other than the skin findings, there are no other health affects. Exogenous Ochronosis may be hard to diagnose.