TNF and systemic sclerosis: Earlier GWAS and SNP studies have confirmed that multiple SNPs of TNF related genes are associated with many immune-mediated disorders, including ankylosing spondylitis (AS) [15], rheumatoid arthritis (RA) [16–18], multiple sclerosis (MS) [19], inflammatory bowel disease (IBD) [20–23], psoriasis [24], systemic sclerosis (SSc) [25–27], and systemic lupus erythematosus (SLE) [28–30].