PDCD1 and systemic lupus erythematosus: The association between checkpoints and autoimmunity has previously been confirmed by the Genome-Wide Association Study (GWAS), in which mutations in the CTLA-4 and PD-1/PD-L1 genes were identified to be responsible for several autoimmune diseases, such as Grave’s Disease and systemic lupus erythematosus (SLE) (72, 73).