The final novel association, at rs2542151 (P=4.6×10-8) maps 5.5-kb upstream of PTPN2 (protein tyrosine phosphatase, non-receptor type 2) on chromosome 18p11. PTPN2 encodes the T cell protein tyrosine phosphatase TCPTP, a key negative regulator of inflammatory responses. The same locus also shows strong association with T1D susceptibility (trend test P=1.9×10-6) and a consistent, though weaker, association with RA (P=1.9×10-2), supporting the existence of overlapping pathways in the pathogenesis of very distinct inflammatory phenotypes (combined trend test P value for all three diseases = 9×10-8) (Table 3; ref. 10).
