Porphyria Educational Services
PORPHYRIA EDUCATIONAL SERVICES
Vol. 2 No. 21 May 21, 2000
FOCUS: VARIEGATE PORPHYRIA [VP]
Variegate Porphyria is often called VP. It is also known by at least three other main names: Porphyria Variegata; Protocoproporphyria; and South African Genetic Porphyria.
VP is an autosomal dominant disorder resulting from a deficiency in protoporphyrinogen oxidase.
VP is one of the three main acute hepatic porphyrias.
Variegate porphyria [VP] is prevalent in South Africa. Most of the VP cases in South Africa have been traced to a couple who immigrated from Holland in the late 1600s, one of whom carried the trait. The majority of VP patients in South Africa are descended from this person and therefore have the same specific mutation.
VP also occurs in many other races. Heterozygotes have an approximate 50% deficiency of protoporphyrinogen oxidase. Many VP
carriers almost never develop symptoms.
A few cases with homozygous deficiencies in protoporphyrinogen oxidase have been described.
Because protoporphyrinogen oxidase is the last of the heme pathway enzymes to be cloned and sequenced, there many different mutations which have recently been identified in unrelated families. As one can speculate, a single mutation is especially common in South Africa.
The symptoms and signs of VP are the same as those for acute intermittent porphyria, except that some patients develop photosensitivity. The skin lesions of VP are indistinguishable from those of porphyria cutanea tarda.
The same triggers that are detrimental in other acute porphyrias can provoke attacks of VP. Skin manifestations often occur apart from the neurovisceral symptoms, and they occur less frequently in cold climates than in hot climates where sunlight is more intense.
In VP patients the ALA and PBG levels are increased, especially during acute attacks.
VP should be considered in the differential diagnosis of acute porphyrias, especially if PBG deaminase activity is normal
Urinary coproporphyrin is markedly and generally persistently increased in VP. Whereas a marked, isolated increase in fecal coproporphyrin is distinctive for hereditary coproporphyria, coproporphyrin and protoporphyrin are about equally increased in VP.
In adults, including latent cases,the fluorescence spectrum of plasma porphyrins is characteristic and very useful for rapidly distinguishing VP from the other porphyrias. This test is probably the most sensitive way to detect VP.
Treatment of acute attacks of VP is the same as that for acute intermittent porphyria. In addiiton VP patients must protect the skin from sunlight. ar Cholestyramine may sometimes decrease photosensitivity.
In VP the use of phlebotomies and chloroquine are not effective.