Patient with phenylketonuria

[IMG SURVIVOR]

You see a kid with all the characteristics of phenylketonuria, but phen. hydoxylase is normal, explain what happend?

[Niacin_05]

Maybe lack of tyrosine in diet? or lack of DHB?

[Unregistered1986]

Maybe lack of tyrosine in diet? or lack of DHB?

What is DHB?

I was thinking it was deficiency of BH4 (cofactor for Phen. hydrolase)