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donutsnduodenums
The kid has albinism, which is due to decreased tyrosinase activity. If he has a problem metabolizing Phenylalanine, he would be presenting with the PKU sx like intellectual disability, musty body odor, etc., in addition to his fair complexion.
+22
zelderonmorningstar
I see, so if it was PKU he wouldn’t just be presenting for a routine examination. It would be one of those “oh crap what’s wrong with my baby” ones.
+16
nbme4unme
Just a note that UWorld says phenylketonuria patients ALSO have albinism, it's just that the neuro sx and musty order are giveaways.
+4
pathogen7
Technically, albinism is a problem processing DOPA, and not tyrosine, no? I always associated "tyrosine processing defect" with ochronosis, which is why I didn't choose tyrosine. Guess I'm wrong.
+5
cmun777
@pathogen7 you're not wrong it is specifically DOPA but would any of the other answer choices make any sense over tyrosine?
+5
- PKU commonly results from deficiencies in the enzyme phenylalanine hydroxylase, which converts phenylalanine to tyrosine.
- Tyrosine, in turn, is required for synthesis of the catecholamines dopamine, norepinephrine, and epinephrine.
- Supplementation with tyrosine effectively bypasses the defective enzyme and allows for the normal synthesis of catecholamines
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submitted by ∗zelderonmorningstar(96)
Can someone explain why the answer couldn’t be phenylalanine?