Alkaptonuria
A rare autosomal recessive condition that results in the accumulation of homogentisic acid in the blood and tissues. The classic finding is darkening of the urine when it is left exposed to open air, but other physical manifestations include hyperpigmentation of cartilaginous structures like the ear, as well as the sclera and corneal limbus of the eye.
Patient 1:
This patient is an old man with alkaptonuria (ochronosis). He was admitted with endocarditis, and was incidentally found to have these greyish discolorations on his eyes, ears and hands. His urine also became darker on standing. Alkaptonuria (ochronosis) was the first human disorder that was recognized to follow the Mendelian pattern of autosomal recessive inheritance. Archibald Garrod introduced the term “inborn error of metabolism” to describe this rare disease.
