CP and Parkinson disease: In this regard, iron specific genetic variants in hemochromatosis (HFE; Guerreiro et al., 2006), transferrin (TF; Rhodes et al., 2014) and ceruplasmin (CP; Hochstrasser et al., 2005; Mariani et al., 2013) genes have been suggested to play a role in the etiology of PD thus offering additional biomarkers for PD.