We have confirmed that the linkage disequilibrium between the IFNL4-∆G allele and IL28B SNP (rs8099917) is high and that the IFNL4-∆G allele is strongly associated with treatment failure of PEG-IFN and ribavirin therapy in patients with Japanese chronic hepatitis C [41]. The gene discussed is IFNL3; the disease is chronic hepatitis C virus infection.