Others used a sensitive prion detection method, protein misfolding cyclic amplification (PMCA), to test milk from scrapie-exposed sheep and found the presence of scrapie prion protein (PrPsc) in milk of sheep carrying at least one VRQ allele [8] although it is not known whether this would lead to disease transmission in a sheep because of the sometimes poor association between PrPsc detection and infectivity [9,10]. The gene discussed is PRNP; the disease is scrapie.