PDC and anemia (phenotype): Hydroxylated prolyl HIF (hyHIF)-α is upregulated in many tumour cells.26 Under cellular circumstances when there is accumulation of hyHIF-α (e.g. due to mutations to the gene encoding for pVHL as occurs in the VHL disease),27,28 or if iron (e.g. in anaemia) or 2OG availability is limiting (e.g. potentially due to mutations in the genes encoding for isocitrate dehydrogenase),29,30 cellular formation of the PHD·Fe·hyHIF-α or PHD·hyHIF-α complexes may become substantial, with consequent potential limitation of the HIF-mediated hypoxic response.