Wednesday, July 11, 2012

Porphyria Variegata

This was a question that was based on clues.  First clue:  I told you it wasn't EBA or PCT.  That clue alone should have made you think in terms of a bullous disease that was, as pictured, on the dorsum of the hands.  Second clue:  I told you the patient had both a psychiatric disease as well as GI pain.  Given only those clues, even had you been blind to the picture, should have made you try to figure out whether it was Porphyria Variegata or Hereditary Coproporphyria.  

I gave credit for both, because in my mind they are clinically indistinguishable.  Only the lab tests will tell the truth, and I will leave that for you to discover on your own.  Suffice it to ay, though, that if you don't think of it, you won't diagnose it. Variegate porphyria is a genetic disease which is incredibly common among white South Africans, which results from a mutation in the seventh step in heme production.  The condition, which is inherited in autosomal dominant fashion, is found in 1/300 white South Africans.  It is characterized by the blistering and skin fragility as in PCT, as well as the symptoms of Acute Intermittent Porphyria, i.e. psychiatric symptoms, as well as abdominal pain, vomiting, diarrhea, and seizures.  It is caused by a mutation in the PPOX gene, which makes the enzyme protoporphyrinogen oxidase. Although this is VP, the same exact symptoms can be caused by hereditary coproporphyria, which is caused by an autosomal dominant defect in the CPOX gene.

p.s. As I told one of our playas, this was PV; the patient was South African.  

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