It is hypothesized that the octapeptide repeat insertion leads to disease by rendering the corresponding mutant PrP protein more prone to adopting a prion‐associated conformation (Li et al., 2011). While large octapeptide repeat insertions lead to prion disease, small octapeptide repeat insertions have not been found to segregate in families with disease. The gene discussed is PRNP; the disease is prion disease.