Interleukin 28 beta (IL28B)
Why this test?
To detect genetic resistance to viral infections and the effectiveness of treatment of chronic hepatitis C with ribavirin ("Rebetol") and PEG-interferon ("PegIntron"). IL28B polymorphism determines both the probability of spontaneous elimination of the virus and the response to antiviral therapy.
In what cases is it prescribed?
Before starting therapy for chronic hepatitis C - predicting the response to treatment;
When choosing a treatment strategy for chronic hepatitis C.
The hepatitis C virus is mainly transmitted through blood. It affects about 3% of the world's population. The infection causes acute hepatitis and is characterized by a lack of sufficient immune response. In 50-80% of cases, it becomes chronic and leads to liver cirrhosis and hepatocellular carcinoma.
Currently, a combination of two drugs - interferon-alpha ("PEG-interferon") and ribavirin - is most often used as antiviral therapy (ART) for hepatitis C, which is confirmed by international research and clinical practice. The main task of antiviral therapy is the prevention of liver cirrhosis and hepatocarcinoma. The course of treatment of chronic viral hepatitis C lasts 16-72 weeks. With such long-term use of these drugs, a number of pronounced side effects develop, so that in some cases treatment has to be stopped. The effectiveness of antiviral therapy depends on many factors: the genotype of the virus, initial viral load, duration of infection, iron metabolism in the body, activity of transaminases, excess body weight, steatosis of the liver, insulin resistance, age, sex, alcohol and drug addiction, concomitant diseases, presence of severe fibrosis .
Achieving a stable virological response, as well as determining the risk of adverse reactions when taking antiviral drugs are very important for the patient. Recently, an individual genetic factor - the status of the IL28B gene - has been used to assess the effectiveness of initial or repeated HVT. It has the greatest diagnostic value in the treatment of CHS caused by the 1st genotype of the virus. In CHC caused by the 2nd and 3rd genotypes of the virus, the IL28B gene polymorphism is significant only for patients who did not achieve a rapid virological response (absence of hepatitis C virus RNA at the 4th week of treatment).
The distribution of IL28B genotypes differs in different populations around the world and explains the different efficacy of antiviral therapy with PEG-interferon and ribavirin in ethnic groups.
Genetic testing is recommended before starting antiviral therapy to predict the effectiveness of therapy and when choosing treatment tactics.
When the SS genotype is detected in a patient, the following is observed: a two- to three-fold increase in the probability of the formation of UVO on PVT; the viral load (the amount of virus in the blood) before treatment is higher than in carriers of TT and ST alleles.
The SS genotype is predominantly found among people with spontaneous termination of infection. Patients with C / T and T / T genotypes are characterized by a decrease in the probable response to PVT, i. e. low treatment efficiency.