Orphanet Prevalence of Rare Diseases 2013, Number 1

This report lists the estimated prevalence of five porphyrias as follows:

Acute intermittent porphyria: 0.54/100,000
Congenital erythropoietic porphyria: Less than 200 cases
Erythropoietic protoporphyria: .9/100,000
Hepatoerythropoietic porphyria: Less than 40 cases
Porphyria cutanea tarda: 4/100,000
http://www.orpha.net/orphacom/cahiers/docs/GB/Prevalence_of_rare_diseases_by_alphabetical_list.pdf