It has been shown in the Russian population that five SNPs in OAS2 and OAS3 genes, as well as two SNPs in IFNL3/IL28B gene and polymorphisms in the TLR3, CD209, and IL10 genes were associated with predisposition to severe forms of tick-borne encephalitis [12–15]. The gene discussed is IFNL3; the disease is tick-borne encephalitis.