What causes the deficits found in children with phenylketonuria (PKU)? 1. They are unable to synthesize melanin, thyroxine and catecholamines. 2. They are unable to synthesize renin, erythropoietin and antidiuretic hormone. 3. They are unable to synthesize aldosterone, cortisol and androgens. 4. They are unable to synthesize neurotransmitters gamma aminobutyric acid (GABA) and acetylcholine.

1. They are unable to synthesize melanin, thyroxine and catecholamines

Explanation:

Phenylketonuria (PKU), is defined as an inherited disorder that causes error of metabolism due to the inability of body to break down phenylalanine into tyrosine.

It occurs due to the defective gene unable to produce phenylalanine  hydroxylase enzymes that convert phenylalanine into tyrosine. Body utilize tyrosine for the biosynthesis of many other proteins such as melanin, thyroxine and catecholamines and perform many other brain function.

Hence, the correct option is  1.