The sanctity of porphyria rareness permeates all that APF is about. Yet pinning down just how prevalent the acute porphyrias really are in the US has never been an easy task. APF’s website states, “taken together, all forms of Porphyria afflict fewer than 200,000 people in the United States.” “16 Shocking Porphyria Statistics” (APF-sponsored) claims, “[t]he exact prevalence of porphyria is unknown, but it likely ranges from 1 in 500 to 1 in 50,000 people worldwide.” Alnylam announced in 2013, “[a]pproximately 5,000 patients in the U.S. and Europe suffer AIP attacks annually….” For whatever reason, US porphyria experts routinely quote European (or “worldwide”) prevalence of AIP (only one of the acute porphyrias)—or lump all of the porphyrias together. Desnick delivered a Powerpoint presentation (undated, but likely in 2013) featuring a slide that cited, “Estimated Prevalence of AIP” [for] Sweden (4-5 patients/100,000), Finland (2-3 patients/100,000), UK & Western Europe (2-5 patients/100,000) and US (2-5 patients/100,000)”/American Porphyria Foundation Patient Registry: 9200 Registered Members, ~3,000 Acute Hepatic Patients, of these the following Are Biochemically/Mutation Confirmed: AIP: 1771, HCP: 420, and VP: 352 Total=2,543. Desiree Lyon told Alnylam Roundtable participants in 2015, “we have 8,700 members with over half of them as patients [incl. all types of porphyria].”
Fast forward to 2018. Based on a study undertaken to evaluate the prevalence, penetrance and heritability of AIP, experts from the French reference center for porphyria (CFP) concluded, “[t]he minimal estimated prevalence of AIP in the general population was 1/1299. Thus, 50 000 subjects would be expected to carry the AIP genetic trait in France.” Six months after the French released that information, an unidentified Alnylam Roundtable advised roundtable participant told the group, “[a French paper reported] that 1 in…1,675 people in France have the gene for porphyria. And one thing to realize is that even if they’re all latent, every single one of those is potentially a porphyria patient because all they need is one dose of sulfonamide antibiotics like I had and their porphyria is woken up.” Not surprisingly, that info tidbit was essentially brushed off.
Fourteen months before Givosiran (aka Givlaari) received FDA approval, an Alnylam executive assured investment analysts, “let me emphasize that porphyria will remain an ultra-rare disease…we’ve been working with the porphyria network….” Ten months later Alnylam executives told investment analysts that givosiran…”would be an attractive ultra-rare orphan disease opportunity with over $500 million in global peak revenue potential.”