Exceptions are BANK1, for which three variants have been associated to SLE and are supposed to lead to an altered B-cell activation threshold (Graham et al, 2009; Moser et al, 2009) and PTPN22, for which Zhang et al have recently developed a knock-in (KI) mouse line expressing the autoimmune disease-associated PTPN22 variant (Pep619W). Here, PTPN22 is linked to autoimmune disease.