Genetic Cause Discovered For Statin-Related Muscle Pain

Some people who take cholesterol lowering drugs, known as statins, have complained of muscle pain.

Now British researchers believe they’ve discovered the genetic cause that underlies the pain and muscle weakness, known as myopathy.

In the July 24 issue online of the New England Journal of Medicine (NEJM), University of Oxford researchers say they’ve found a gene variant that affects the transportation of statins into the liver. 

Dr. Rory Collins, a professor of medicine and epidemiology there says, “That variant produces a high level of blood statins and accounts for the greatest proportion of myopathy in people who use statins.”

Muscle pain, though not uncommon, occurs in roughly one out of every 1,000 person on statins.  While about a quarter of the population carries one of the genes, a smaller percentage carries two copies.

Two copies of the variant gene carry a 15-fold increased risk for muscle pain. It’s estimated about two percent of the population carry two variant genes.

It is the genetic variant that accounts for about 60 percent of the statin-related myopathy.   Muscle pain may also depend on how much of the statin is given to the patient.

"For the statin doses most usually used, 20 to 40 milligrams of simvastatin, for example, the risk of myopathy is very low," Dr. Collins tells the Washington Post.  "Using a high dose for someone at high risk, the absolute risk of myopathy is maybe one in 1,000. With a standard dose, the risk would be about one in 10,000."

Patients are given statins to lower cholesterol levels to avoid a buildup of the fat-like substance along arteries that contribute to heart disease.

Popular statins are Mevacor (lovastatin), Pravachol (pravastatin), Zocor (simvastatin), Lescol (fluvastatin),  Lipitor (atorvastatin), and Baycol (cerivastatin).   

A genetic test is recommended to determine if a person has two of the genetic variant genes before large doses of statins are recommended.  #