PTPN22 and rheumatoid arthritis: Genes involved in autoimmune disease origins and human longevity23,57, rheumatoid arthritis development58 were related to Factor 4 (HLA DQA1, PTPN22).The common signal in the GWAS of the latent factors was also HLA (GWAS factor 1, factor 3 and factor 4) suggestive of the involvement of HLA in MLTC incidence.