QuestionSBA
QuestionChoice
No, this is not the correct answer. Patient's with homocystinurias are deficient in cysteine. Make sure you do not confuse this with phenlyketonuria.
10007884
e
Cysteine
QuestionChoice
No, this is not the correct answer.
10007883
d
Threonine
QuestionChoice
No, this is not the correct answer. Phenylalanine is in excess within the bloodstream with patient with PKU.
10007881
b
Phenylalanine
QuestionChoice
Yes, this is the correct answer. The enzyme deficiency in PKU prevents the conversion of phenylalanine to tyrosine. This leads to the excess of phenylalanine within the bloodstream and a deficiency of tyrosine. The excess of phenylalanine leads to the excess of phenylacetate and phenylacetate (phenylketones) within the urine. Tyrosine is vital in the synthetic pathway of adrenaline, noradrenaline, dopamine, melanin, and thyroid hormone synthesis (T3 & T3), hence it is relatively simple to predict the patient's signs and symptoms if they are deficient in tyrosine.
10007880
a
Tyrosine
QuestionChoice
No, this is not the correct answer.
10007882
c
Tryptophan
Concept
Chapter
2693
4627
Phenylketonuria
Topic
153
Paediatrics
14123
A genetic test is performed for a 3 day old neonate due to recent episodes of seizures and skin hypopigmentation. A diagnosis of phenylketonuria (PKU) is made.

The paediatrician explains PKU is associated with the deficiency of an enzyme known as phenylalanine hydroxylase, in turn leading to deficiency of an endogenous amino acid responsible for the synthesis of catecholamines and various other compounds.

Which of the following amino acids is the neonate most likely to be deficient in?
a