PTPN22 and systemic lupus erythematosus: PTPN22 has strong functional consequences for immune responses, supporting evidence of association with SLE and other autoimmune diseases [4], [5], [6], [7], [8], [9], [10], [11], [12], [13], [14], [15], [16], [17], [18], [19], [20], [21], [22], [23], [24], [25], [26], [27].