Monday, June 18, 2012

Deficiency of Uroporphyrinogen Decarboxylase

Uroporphyrinogen decarboxylase, the enzyme deficiency of which leads to porphyria cutanea tarda, is the most common of the heme-synthesis enzyme deficiencies.  Of course, it is characterized by many cutaneous manifestations, including scarring and blistering and skin fragility of the hands, hypertrichosis of the bitemporal area, subungual onycholysis, and as you can see above, extensive photoaging and textural differences on the nasal bridge.  This finding is also common for those who have Erythropoietic Protoporphyria, and so if anyone had said Ferrochelatase as the answer, I would have given them credit.

As we have discussed previously with PCT, it is important that patients who display the findings of PCT get a full workup for liver disease and hemochromatosis, either familial or alcohol induced.The mechanism of alcohol induction is thus:  the enzyme is present in large concentration in the hepatocytes, and when large amounts of ethanol are ingested, it causes oxidative damage to the hepatocytes, which in turn damages the cytosolic enzymes within.  This patient, however, had estrogen-induced PCT, which is a story for another day.

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