Two patients with the G131V mutation have been published previously [22, 30]. In our transmission studies, which used tissue from the second patient, all the tg66 mice injected with G131V patient brain were negative for PK-resistant PrPSc by immunoblotting and PrP amyloid seeding activity by RT-QuIC assay, but all had detectable PrPSc by IHC. There reasons for these discrepancies are not known, but the lack of a confirming biochemical test for PrPSc or seeding activity, weakens the interpretation that transmission was truly positive. Perhaps the second passage in tg66 mice will be able to clarify these conclusions.