What Is Q80k Polymorphism?

A great deal of research has been done on the hepatitis C virus (HCV). Researchers now understand many things about the virus and how it affects people. Studies have shown that there are multiple forms, or strains, of HCV.

A common strain of HCV in the United States contains the Q80k polymorphism. In our 2018 Hepatitis C In America survey, we asked survey takers if they have Q80k polymorphism. About 97 percent of surveys takers who had not yet been cured answered “I don’t know/I’m not sure”.

What is Q80k polymorphism?

Q80K is a scientific term to represent a specific DNA change in the strain of HCV. Think of DNA like a story or instruction manual for how the virus acts. It is made up of millions of “base pairs”, or letters. These letters are grouped into “codons”, or words. Each codon represents an amino acid, which is a building block for protein.

Scientists have ways to remove the DNA from virus cells. It can then be “sequenced”, or read, by the scientists. Once it is sequenced, the scientists can study the DNA and compare it to DNA from other viruses. That allows them to group different strains of HCV together into genotypes and subtypes to understand them better.

There are often many strains of viruses that look slightly different genetically but all act similarly. Each strain is considered a genotype. It is similar to the idea of dog species. For example, chihuahuas and golden retrievers look different, but they are both still dogs.

Within each of these HCV genotypes, there are subtypes. The genotypes are divided into subtypes by looking at the DNA and grouping the viruses by their similar features. One method of grouping is looking at polymorphisms. The word "polymorphism" means “many forms”. It is more specific than genotype. It refers to the fact that even within 1 strain or 1 subtype of the virus, there may be very small differences. These changes in DNA occur naturally because the virus replicates so many times. There is no way to “get” or “catch” the Q80K polymorphism. It is simply a natural variation of the HCV virus.¹

HCV strains with the Q80K genotype have a few different base pairs at position 80. This “letter” change results in a new “word” or amino acid. That small change in the DNA “story” can have important effects on how the virus functions or how it can be treated.

How do I know my hep C virus strain?

When a person is diagnosed with HCV, their doctor may recommend DNA testing to see what genotype of HCV they have. Laboratory scientists will then look at the entire strand of DNA to see what changes are there. If they see this particular amino acid change at position 80, they know this patient has HCV subtype 1a, Q80K mutation.²

Is Q80K polymorphism treated differently?

There are many drugs used to treat HCV. These drugs are often used in different combinations. The newest class of HCV drugs are called direct-acting antivirals (DAAs). They are specific for different strains of HCV to prevent the virus from replicating. These drugs attach directly to the virus because they are able to recognize certain patterns in the DNA. Because of this, certain drugs are more or less effective depending on the strain of HCV.³

If you have HCV and would like to learn more about DNA testing for Q80K, reach out to your doctor.