Among them, two genes [nitric oxide synthase 2 (NOS2) and nitric oxide synthase 3 (NOS3)] were associated with all MLB, RA, and LA; four genes (interleukin 2, interleukin 1 beta, caspase 3, and v-rel avian reticuloendotheliosis viral oncogene homolog A) were associated with both MLB and RA; and four genes (xanthine dehydrogenase, aldo-keto reductase family 1 member B1, protein tyrosine phosphatase no-receptor type 1 and procollagen-lysine, and 2-oxoglutarate 5-dioxygenase) were associated with both MLB and LA. The gene discussed is XDH; the disease is rheumatoid arthritis.