Past reports have also observed a high prevalence of HLA-DRB1*04 alleles in both diseases (86.7% in FS; 82.8% in LGL leukemia/RA patients; 31.4% in LGL leukemia patients, which is similar to control population rates) (66) as well as response to methotrexate therapy in both diseases (90). The gene discussed is HLA-DRB1; the disease is rheumatoid arthritis.