PTPN22 and rheumatoid arthritis: Good examples of known shared risk loci in IMDs are PTPN22, IL23R and TNFAIP3, which have allowed the repositioning of anti-TNF and anti-IL-12/IL-23 therapies to be used in rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE), among others [1].