Inheritance: autosomal dominant
Genetic locus: 18q21.3
Clinical features:
(1) skin urticaria and erythema
(2) neurovisceral signs and symptoms may occur rarely
(3) acute attacks can unlikely
(4) positive family history
(4) occasional patients may develop active liver disease
Laboratory findings (more pronounced during an acute attack):
(1) porphobilinogen and aminolevulinic acid are not increased in the urine
(2) coproporphyrinogen III and/or uroporphyrinogen are not increased in the urine
(3) protoporphyrin in the feces is variable (may be increased or decreased)
(4) erythrocytes show an increase in protoporphyrin
(5) presence of a mutation in ferrochelatase
