Coproporphyrinogen oxidase (CPO) converts coproporphyrinogen III to protoporphyrinogen IX. A patient with hereditary coproporphyria (HCP) has a defect in this enzyme.


Inheritance: autosomal dominant


Genetic locus: 3q12


Clinical features:

(1) bullae and skin fragility

(2) neurovisceral signs and symptoms

(3) acute attacks can occur

(4) positive family history


Laboratory findings (more pronounced during an acute attack):

(1) porphobilinogen and aminolevulinic acid are increased in the urine with greater amounts of porphobilinogen

(2) coproporphyrinogen III is increased in the urine

(3) coproporphyrinogen III is increased in the feces

(4) erythrocytes do not show an increase in porphyrins

(5) presence of a mutation in coproporphyrinogen oxidase


To read more or access our algorithms and calculators, please log in or register.