In comparison, in sporadic prion disease in patients with MM genotype at codon 129 of the PRNP gene, the average 50% seeding dose (SD), assessed with RT‐QuIC assay, corresponds to approximately 1010 /g brain, or 1 SD50 unit equivalent to 0.06–0.27 fg of PrPSc146. This evidence concerns the gene PRNP and prion disease.