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Hepatitis C Genotypes, Explained

Hepatitis C Genotypes, Explained

Learn what hep C genotypes are and why knowing your genotype is important to your treatment.

An infection with the hepatitis C virus (HCV) causes inflammation in the liver. Over time, a chronic HCV infection can result in significant damage and scarring to the liver, though it often causes no noticeable symptoms, and a person can have hep C and not know they have it.

If you’ve read about hep C or talked to a healthcare provider about hep C, you’ve probably come across the term genotype. When talking about hep C, genotypes refer to different versions of the HCV virus. There are six major genotypes of the hepatitis C virus (HVC) found throughout the world—simply called genotypes 1 through 6—though a seventh genotype has been identified. HCV is further classified by subtypes, which are labeled with letters—a, b, c, d and so on.

Categorizing HCV by genotype helps healthcare experts understand hepatitis C at a global scale—an estimated 130-150 million people worldwide are infected with hepatitis C. Knowing the genotype of an HCV infection is also important to healthcare providers and patients, because different hepatitis C genotypes respond differently to certain treatments.

What causes different genotypes of HCV?
Viruses evolve, just like any other living organism. As the HCV virus has replicated an incalculable numbers of times (there have been hundreds of millions of cases throughout the decades, and the virus can replicate inside the body trillions of times in a single day) new genetic traits emerge, due to mutation, errors in RNA and adaptation. Over time, different genotypes emerge.

How do you know your hep c genotype?
Hepatitis C is diagnosed through a series of blood tests. The initial screening is a hep C antibody test that will show whether you have ever had HCV. In somewhere between 20 to 40 percent of people that contract HCV, the virus clears without leading to a chronic infection. If the antibody test is positive, a follow-up test will confirm whether an HCV infection is active. If the infection is active, additional testing will be used to determine the viral load and genotype.

Are some genotypes more common than others?
Overall, genotype 1 (which includes subtypes 1a and 1b) is the most common hep C genotype worldwide, and is the most common in the United States. However, different genotypes are more common in different parts of the globe. For example, genotype 3 is the most common genotype in Southeast Asia, Australia, Africa and the Middle East.

How does the genotype impact treatment?
There are numerous medications available for treating hepatitis C. Specific medications are better for certain genotypes, though some treatments are effective at treating multiple genotypes. Treatment typically involves a course of one or more medications taken over several months.

However, genotype is only one factor that must be considered when deciding on treatment for hep C. The health of the liver, overall health, other medical conditions, pregnancy and previous treatments are other factors that a healthcare provider will take into account when deciding on a course of treatment.

Medically reviewed in September 2018.

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