All the following statements about phenylketonuria are correct except?

(A) Phenylalanine cannot be converted into
tyrosine
(B) Urinary excretion of phenylpyruvate and
phenyllactate is increased
(C) It can be controlled by giving a lowphenylalanine
diet
(D) It leads to decreased synthesis of thyroid
hormones, catecholamines and melanin