ABSTRACT
The urine in patients with alkaptonuria contains excessive quantities of homogentisic acid, a metabolite of tyrosine, and Garrod proposed that this was due to decreased activity or absence of an enzyme responsible for the metabolism of homogentisic acid. This hypothesis was only proved correct in 1958 when La Du reported a deficiency of the enzyme homogentisic acid oxidase in patients with alkaptonuria.
