Transgenic mice expressing human PrP 129 valine, but not mouse PrP (129VV Tg152 mice), lack a transmission barrier to classical (sporadic and iatrogenic) CJD prions, regardless of the codon 129 genotype of the inoculum (Collinge et al.1995, 1996; Hill et al. 1997; Wadsworth et al. 2008; figure 2). The gene discussed is PRNP; the disease is Creutzfeldt Jacob disease.