HCV, which is principally transmitted by blood, infects about 3% of the world's population. HCV infection causes acute hepatitis, which is self-resolving in 20 to 50% of cases but does not confer permanent immunity. In 50 to 80% of cases, HCV infection becomes chronic and results in chronic hepatitis, cirrhosis, and hepatocellular carcinoma. As a result, HCV infection is a leading killer worldwide and the most common cause of liver failure in the U.S. HCV is opportunistic in individuals infected with human immunodeficiency virus (HIV; see 609423), approximately 25% of whom are coinfected with HCV. HCV infection is also associated with cryoglobulinemia (see 123550), a B-lymphocyte proliferative disorder (Pawlotsky, 2004; Chisari (2005); Pileri et al., 1998). [from
OMIM]