Porphyrias

From a Lancet review:

Hereditary porphyrias represent a group of 8 metabolic disorders of the haem biosynthesis. They are characterised by acute neurovisceral symptoms, skin lesions, or both.

Every porphyria is caused by abnormal function of a separate enzymatic step, resulting in a specific accumulation of haem precursors:

- 7 porphyrias are the result of a partial enzyme deficiency
- a gain of function mechanism is present in one new porphyria

Acute porphyrias present with acute attacks - severe abdominal pain, nausea, constipation, confusion, and seizure - and can be life-threatening.

Cutaneous porphyrias present with painful photosensitivity, skin fragility and blisters.

Porphyrias are still underdiagnosed. Screening of families to identify presymptomatic carriers and avoidance of precipitants is important.

References:
Porphyrias. The Lancet, Volume 375, Issue 9718, Pages 924 - 937, 13 March 2010.

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