Porphyria Educational Services
PORPHYRIA EDUCATIONAL SERVICES
BULLETIN
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.