PDCD1 and systemic lupus erythematosus: Allele T of a single-nucleotide polymorphism (SNP) corresponding to PD-1.5 C/T (dbSNP rs#cluster id rs2227981) was found to be associated with the development of RA (odds ratio (OR) 1.94, 95% confidence interval (CI) 1.25 to 3.01, p < 0.0025) but not SLE in Chinese patients living in Taiwan [17].