By Jenna Fletcher

Reviewed by Cameron White, MD, MPH

Hepatitis C is liver inflammation that results from a viral infection. It may not cause symptoms, so it can go undetected for years.

As the infection progresses over many years, it can cause liver damage. This may take the form of scarring, permanent damage called cirrhosis, and liver cancer. Hepatitis C can greatly impact the liver’s ability to function.

The Centers for Disease Control and Prevention (CDC) estimate that in 2016, around 2.4 million people in the United States had hepatitis C.

Hepatitis C results from infection with a certain type of virus made up of single-strand RNA. This RNA contains the virus’s genetic code and building blocks. The particular strain of a hepatitis C virus determines how healthcare providers treat the infection.

Genotypes are classifications of hepatitis C virus based on the virus’s genetic makeup. There are six main genotypes of the virus, as well as several subtypes.

The genotype a person with hepatitis C carries can help determine their treatment. Options also differ depending on whether or not a person has cirrhosis and whether or not they have previously received treatment for hepatitis C.

Keep reading to learn more about hepatitis C genotypes and what they mean for a person with the infection.

What are genotypes?

There are six hepatitis C genotypes, numbered 1–6. There are also subtypes, designated with a letter — for example, 1a or 1b.

People with hepatitis C are most likely to carry a single genotype — that of the virus responsible for the initial infection. If a person carries more than one genotype, doctors call this a mixed infection.

According to the United States Department of Veterans Affairs:

• around 75% of people with hepatitis C in the country have genotype 1
• around 20–25% have genotypes 2 or 3
• the remainder have genotypes 4, 5, or 6

There is limited evidence about how different genotypes affect the progression of the condition. However, the virus genotype that a person carries can affect their treatment options.

Testing for genotypes

Because the hepatitis C virus’s genotype can help determine the right course of treatment, it is important to identify the genotype in every person with the infection.

Healthcare providers determine genotypes using blood tests. They may draw the blood either from the arm or the finger, then they will send the blood sample to a laboratory for analysis.

The laboratory staff will identify the genotype and estimate how much of the virus is in the person’s blood. This is called a viral load, and it can also help determine the best course of treatment.

How do genotypes affect treatment?

The genotype does not affect the virus’s potential to damage the liver. Each genotype carries a similar risk.

However, carrying the 1b genotype may increase the risk of cirrhosis, which is scarring of the liver that can impede its function. Also, carrying the subtype 1b or genotype 3 may increase someone’s risk of developing liver cancer.

Regardless of the virus’s genotype, the treatment for hepatitis C involves taking direct acting antivirals (DAAs). These oral medications prevent the virus from replicating and spreading.

DAAs latch onto proteins in the virus and block their essential functions. This prevents the virus from replicating, allowing the person’s immune system to eliminate it.

The goal of hepatitis C treatment is to cure the infection. Healthcare providers say that it is cured when the person has undetectable levels of hepatitis C virus in their blood, or a sustained virologic response.

Some DAAs are better at targeting specific genotypes of the virus.

Treatments for different genotypes

DAAs are the most common treatment that directly targets the hepatitis C virus. A person may also need to take other medications, depending on the genotype of the virus and any complications of the infection.

The best treatment option tends to depend on whether or not the person has cirrhosis. The options below apply to people who have not previously received treatment for hepatitis C.

The following medications are recommended for genotypes 1a and 1b:

• elbasvir and grazoprevir (Zepatier)
• simeprevir and sofosbuvir (this is not the first line treatment)
• ledipasvir and sofosbuvir (healthcare providers may also prescribe this for genotypes 4 and 6)
• glecaprevir and pibrentasvir
• sofosbuvir and velpatasvir

If a person has genotype 2 or 3, a healthcare provider may choose to prescribe glecaprevir and pibrentasvir or sofosbuvir and velpatasvir.

For people who have genotype 4, they may prescribe glecaprevir and pibrentasvir, sofosbuvir and velpatasvir, elbasvir and grazoprevir, or ledipasvir and sofosbuvir.

For people with genotypes 5 or 6, they may describe a combination of these medications. As one study paper concludes, developing more effective treatments and a better understanding of the prevalence of the condition will require more research.

The right treatment varies from person to person. When recommending a course of action, a healthcare provider will take into consideration previous treatments, medical history, overall health, and any complications of hepatitis C.

Here, find out more about the range of medications available for hepatitis C.

Do genotypes change over time?

Typically, the virus’s genotype stays the same. However, the hepatitis C virus can mutate. The mutation may have no effect, or it may allow the virus to become resistant to treatments.

Hepatitis C treatment typically involves more than one type of medication. This helps prevent the virus from developing drug resistance.

Who has which genotype?

A person with hepatitis C carries the genotype of the virus that caused the infection. People of all races, ethnicities, and backgrounds can carry any genotype.

However, certain genotypes are more common in certain parts of the world.

According to a study from 2015, globally:

• 46.2% of people with hepatitis C carry genotype 1
• 30.1% carry genotype 3
• 22.8% carry genotypes 2, 4, or 6
• fewer than 1% carry genotype 5

The authors of that study explain that genotypes 4 and 5 are more prevalent in countries with lower average incomes.

Summary

Genotypes are categories of hepatitis C virus. Some medications are better at treating certain types or subtypes of virus.

Carrying certain genotypes of the virus can raise the risk of experiencing certain complications, such as scarring.

Healthcare providers determine genotypes using blood tests. The results will help determine the best course of hepatitis C treatment for each person.