KIF6 Testing and Heart Disease

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KIF6 Testing and Heart Disease

What Is KIF6?

KIF6 is a gene. Its job is to make a protein involved in moving things around inside your body's cells. In 2008, a group of researchers found that a very common variation in the KIF6 gene seems to increase a person's chance for heart disease. The reason why isn't known.

Variations in our genes are normal. These variants make each of us unique. Researchers are working hard to find out which gene variants might help predict a person's risk for health problems, like heart disease. See What Is a Variant? for more information.

KIF6 and Heart Disease Risk

There are two common forms of the DNA code at a certain place in the KIF6 gene. The typical form is called "Trp". A different or variant form that predicts a higher risk for heart disease is called "Arg". Read the box below to find out why the variants are named this way.

KIF6: Trp and Arg Variants

The DNA code is read in groups of 3 letters at a time to tell the body what amino acid to put next in the protein it is making. A gene with the DNA letter "G" puts an arginine (or "Arg") into the protein. A gene with the DNA letter "A" puts a tryptophan (or "Trp") into the protein. This DNA variation affects the 719th amino acid, so the variants may also be called "719Arg" or "719Trp".

People have two copies of the KIF6 gene in each cell — one inherited from each parent. Having at least one copy of the Arg variant may raise the risk for heart disease a small amount. Researchers found that people with at least one Arg variant (called "Arg carriers") have a 1.2 to 1.5 times higher chance for heart disease than people who don't have an Arg variant. Recently, however, other researchers found that having an Arg variant makes no difference in risk for heart disease.

KIF6 Risk Example

The actual risk for heart disease depends on a combination of factors. This example uses a made up person as an example of how KIF6 test results may change heart disease risk.

Example starting risk for heart disease:
about 10%
Heart disease risk if a KIF6 Arg carrier:
12% to 15%

If the first group of researchers is right, this amount of risk is similar to other things that we know affect heart disease risk — like diabetes, age, and cholesterol. The chart below shows how these risk factors compared to each other in one study. See What Are The Risk Factors For Heart Disease? to learn more about what causes heart disease.

Since the research on KIF6 is equally divided into studies that show a higher risk and studies that don’t, it’s not clear yet if KIF6 testing should be recommended. More research is in progress.

KIF6 and Statin Response

Having at least one Arg variant may mean that statin drugs will be more effective for you. In one study, Arg carriers who took statins lowered the risk for heart disease by 37% to 50%. People without the Arg variant only lowered their risk by 6% to 20%. Recent research, however, did not find any difference in how people respond to statins.

One of the challenges of the research so far is that is that none of the studies were originally designed to study the KIF6 gene. Instead, the KIF6 analysis was done after the studies were completed. This means that there could be issues that weren’t taken into account during the study that could have affected the KIF6 results. So, we don’t know for certain yet if the KIF6 variant predicts a person’s risk for heart disease and their response to statins, or exactly how this information can be used to prevent heart disease. More research is in progress.

Next: Who Should Consider KIF6 Testing?

What is your main reason for considering KIF6 variant testing?

My doctor has recommended or prescribed statin drugs.

I want to know more about my heart disease risk.

None of these.

Statins are a commonly prescribed class of drugs which that help lower cholesterol. Examples of statins include Lipitor® (atrovastatin), Zocor® (simvastatin) , Crestor® (rosuvastatin) and Pravachol® (pravastatin).

If your doctor has recommended or prescribed statin drugs for you, you probably already have known heart disease risk factors. KIF6 test results won't change your other risk factors or your need to be treated for this risk. The results may strengthen the argument for statin therapy though.

If you have a KIF6 risk variant:

  • The results add to the signs you already have that your risk for heart disease is higher-than-average.
  • If you aren't sure that you need statins or want to take them, knowing you have a KIF6 risk variant could help make your decision.
  • Many people have trouble taking prescribed drugs regularly over a long period of time. Knowing that you have a risk variant could help you to take your drugs as prescribed.
  • Statin drugs are usually prescribed with lifestyle changes too. Lifestyle changes are key to lowering your heart disease risk. If you've had difficulty making necessary lifestyle changes, knowing you have a genetic risk could motivate you.
  • One study showed that people with a KIF6 risk variant may get even more benefit from intensive statin therapy (different statin drugs or higher doses). Your doctor may consider the KIF6 results in deciding how to prescribe statin therapy for you. However, experts don't agree about whether KIF6 results should change statin prescribing.

If you don't have a KIF6 risk variant:

  • The results don't change the fact that you have an increased risk for heart disease for other reasons.
  • The KIF6 risk variant may be only one small part of all of the things that cause heart disease.
  • People with a higher risk for heart disease still benefit from taking statins — regardless of their KIF6 results. Not having a KIF6 risk variant isn't a reason to decide against statin drugs or other risk-lowering treatments.

Never stop taking a drug, change dosage, or change a treatment your doctor prescribed without talking to your doctor first.

The KIF6 variant may be one of many things that raise heart disease risk, but this research is still in the early stages. Some important things need to happen before KIF6 is proven to help predict heart disease risk and response to statin drugs:

  • Other researchers need to confirm that there is a definite relationship between heart disease and the KIF6 gene. The mechanism by which this gene could affect heart disease needs to be determined.
  • The connection between KIF6 and heart disease needs to be tested in people from other ethnic groups — most research has been done on Caucasians (white people).
  • Experts need to figure out how to include KIF6 test results with the other factors already proven to predict heart disease risk, like age, cholesterol levels, high blood pressure, smoking, and diabetes.

For now, KIF6 testing may give you some information about this one risk factor, but your results may not change your medical care.

You may also be interested in the American Heart Association's Risk Calculators which give you a personal risk for heart attack or dying from heart disease based on the main proven heart disease risk factors. It also gives you suggestions for how to lower your risk. It does not include KIF6 genetic test results though.

Since the connection between the KIF6 variant and heart disease is controversial, it's not clear how this information can or should be used to change your medical care. This area of research is relatively new and it takes time to study how results like these may be useful.

KIF6 testing probably isn't useful for:

  • People with an average risk for heart disease. A KIF6 risk variant alone may not be a strong enough risk factor to change your overall risk or how you are treated.
  • People with a strong family history of heart disease, especially if heart disease starts at an unusually young age (before 55 for men or 65 for women). There are important genetic causes of heart disease other than KIF6. If you have a family history of heart disease, discuss it with your doctor or a genetic counselor.

If you have a reason for KIF6 testing that isn't covered here, talk to your doctor or a genetic counselor about whether testing might be useful for you.