Dec. 17, 1999 (Indianapolis) -- It has long been known that the outcome of an infection with the hepatitis C virus (HCV) can vary greatly among individuals. A report in the Dec. 18 issue of the journal The Lancet indicates that a patient's genetic factors may explain much of this variability.
"Infection with HCV can lead to anything from a self-limiting [mild and noncontagious] infection to cirrhosis, or scarring of the liver, to cancer," says lead author Mark Thursz, MRCP, from the Imperial College School of Medicine in London. "In some patients, the rate of progression is much faster than average, whereas in others, the rate of progression is negligible. What determines the outcome of HCV infection is not clear."
Hepatitis C is a virus that can cause liver disease and liver cancer. It is transmitted via blood, either from blood transfusions or IV drug use. It can also be transmitted from sexual contact. Initially it may cause a mild illness, but then resides in the body without symptoms. In at least 20% of cases, the HCV will reactivate and eventually cause a liver disease called cirrhosis. There are treatment options for HCV, many experimental, but there is no known medication that kills the virus.
Using patients recruited from eight large hospitals across Europe, the researchers looked at the distribution of a set of certain genes in patients with a self-limiting infection that went away on its own and a matched set of patients with a persistent infection. They also studied those with mild and severe injury to the liver and those patients who responded to treatment with interferon and those who did not.
Those with the self-limiting type of infection were more likely to have two specific genes. Two other genes were associated with persistent infections. These results were confirmed in a second-stage study. No significant associations were found between the presence of certain genes and injury or response to interferon.
"In the short term, this research has no direct relevance to the patient," says Thursz in an interview with WebMD. "However, in the future, identification of genetic factors which influence the outcome of hepatitis C virus infection will be used to identify patients at most risk of developing severe liver disease, identifying patients with a good chance of responding to treatment, and identifying disease pathways as targets for therapeutic intervention."
David L. Smalley, PhD, professor of pathology at the University of Tennessee, Memphis, agrees with the researcher's statement that a complex mix of genetic, environment, and virus factors determines the outcome of HCV infection.
"Genetics is one component that affects the outcome of HCV," says Smalley in an interview with WebMD. "This is one step in the right direction to find the genetic effects that might allow us to determine an intervention's success or failure. For us to fully understand a disease that evolves over a 20- or 30-year period of time, it is clear that we have to look at many other factors."
Leslye D. Johnson, PhD, who is with the National Institute of Allergy and Infectious Diseases, tells WebMD in an interview that this will probably give researchers a way to narrow the scope of future studies in an attempt to find something that is useful in treating patients.
"I don't think the results of this will be clinically useful," says Johnson, who was not involved in the study. "Although looking at these genes might give you some idea of what was going to happen, it is not going to be predictive."
- Hepatitis C virus (HCV) is transmitted via blood transfusion, IV drug use, or sexual contact and can cause a variety of ills, including a mild infection, liver disease, or liver cancer.
- A new study shows that genetic factors influence which HCV patients will have a self-limiting type infection or a more persistent infection.
- This new information could help patients in the future, but for now they must rely on many experimental treatments, none of which can kill the virus.