Historically, HCV treatment has been less effective for African Americans than for Caucasians. This is partly—but not completely—explained by genetics: researchers identified a gene that is linked with response to pegylated interferon–based treatment, called IL-28B (see “How is it diagnosed, and what tests are used?” for more information on IL-28B). 
However, clinical trials of Sovaldi did not find any difference in cure rates between black and non-black study participants.