Disorders In-Depth
The Acute Porphyrias
Four of the porphyrias cause acute neurological symptoms. They are not common and may be difficult to diagnose. It is estimated that about 1 in 10,000 Europeans or people of European ancestry carries a mutation in one of the genes for acute porphyria, although mutations have been found in all races and many other ethnicities.
Variegate Porphyria (VP)
VP is especially common in South Africa in individuals of Dutch ancestry, and has an incidence of approximately 3 per 1,000 in whites, but is less common than AIP in other countries. It is caused by a deficiency of the enzyme protoporphobilinogen oxidase (PPOX). Acute attacks are identical to those in AIP, and their management and prevention are the same as in AIP. Blistering skin lesions are much more common than in HCP and are not readily treated. Urine ALA and PBG are increased during attacks, but as in HCP, these may increase less and decrease more rapidly than in AIP. Plasma porphyrins are frequently increased in VP, in contrast to AIP and HCP, and the plasma of VP patients displays a distinctive fluorescence peak, which is diagnostic. Fecal porphyrins are also elevated and are predominantly coproporphyrin III and protoporphyrin. Long term complications are the same as in AIP.
