Two variants in ATIC (rs4673993, T allele) and SLC19A1 (rs1051266, C allele), which impact methotrexate (MTX) efficacy in rheumatoid arthritis (Chen et al., 2017), demonstrated high prevalence among the enrolled Saudis with allele frequencies of 71% and 48%, respectively. The gene discussed is SLC19A1; the disease is rheumatoid arthritis.