Phenylketonuria....?

Why is it called Phenylketonuria?

The name of this disease actually come from Phenylalanine & one of the dominant metabolites which contains a ketone group (phenylpyruvate, an alpha-keto acid) circled in red in the pic above.

Introduction to Phenylketonuria. Retrived July 1, 2012, from http://www.uic.edu/classes/phar/phar332/Clinical_Cases/aa%20metab%20cases/PKU%20Cases/PKU%20biochem%20intro.htm