FADS1 and 2 (Fatty Acid Desaturase) and BLK (BLK Proto-Oncogene, Src Family Tyrosine Kinase), involved in fatty acid metabolism, and STAG1 (Stromal Antigen 1) and FCGR2B (Fc Fragment Of IgG Receptor IIb), involved in lipoprotein metabolism, were found to be associated with susceptibility to developing RA in several studies [103,104,105,106,107]. Here, BLK is linked to rheumatoid arthritis.