PDCD1 and systemic lupus erythematosus: In this work, PD-1.1 G/A (rs36084323), a nonfunctional SNPs in PDCD1, was studied in a Chinese Han population, aiming to explore whether PD-1 expression was related to the variant of the SNP PD-1.1 G/A (rs36084323) and SLE Disease Activity Index (SLEDAI).