alkaptonuria
what enzyme is absent? in which pathway?
findings

homogentisate oxidase
(catalyze the production of ¥maleylacetoacetic acid from homogentisic acid)

from ☆tyrosine to fumarate

debilitating arthralgias, bluish-black connective tissue(☆ear cartilage, sclerae), ☆urine turns black on prolonged exposure to air

biochemistry UWorld Amboss level4