We stratified CJD cases depending on the codon 129 polymorphism of PRNP gene, but no differences in YKL-40 concentrations were detected between methionine/methionine (MM) (165 ng/mL, n = 49), methionine/valine (MV) (212 ng/mL, n = 10) and valine/valine (VV) (173 ng/mL, n = 13) cases (Fig. 2a). The gene discussed is PRNP; the disease is Creutzfeldt Jacob disease.