Medical Genetics Phenylalanine Phenylpyruvic acid Phenylketonuria Phenylalanine block hydroxylase rosine 3, 4-dihydroxyphenylalanine (DOPA) Melanin pigments Ty rosine Co2+H2o- transaminase Citric acid cycle p-hydroxyphenylpyruvic acid Fumaric+T- Acetoacetic id acid p-hydroxyphenylpyruvic Fumarylacetoacetic acid acid oxidase Homogentisic acid oxidase Homogentisic acid 2, 5-dihydroxyphenylacetic acid Maleylacetoacetic acid Phenyl ketonuria lug Cummings 1997)Medical Genetics