IFNA1 and chronic hepatitis C virus infection: In German patients suffering from chronic hepatitis C and treated with IFN-α, it was found that pretreatment viral factors, not host factors, were significantly correlated with treatment response [45], In Spanish population, although HLA class II showed no effect on response to interferon treatment, HLA class I-B44 was associated with response to combined therapy of IFN and ribavirin, not with interferon alone [46].