London, ON – A worldwide study involving the genetic testing of more than 100,000 people has identified the genes that control lipid levels, in particular: LDL (bad cholesterol), HDL (good cholesterol) and triglycerides. It found 95 genes associated with lipid levels, including 59 identified for the first time.
The study by the Global Lipids Genetics Consortium, made up of more than 200 researchers worldwide and led by Dr Sekar Kathiresan of Harvard Medical School, is published in Nature.
There were four Canadian sites involved in the study including London, Hamilton, Ottawa and Montreal. Dr Robert Hegele of the Robarts Research Institute, Schulich School of Medicine & Dentistry at the University of Western Ontario was the senior Canadian author, providing samples and analysis of triglycerides, together with graduate student Christopher Johansen.
“Most studies up to this point involved Caucasians. This study looked at all ethnic groups, and it’s such a large sampling that it provides us with a definitive picture of genes that contribute to cholesterol and triglyceride levels, both of which are important risk factors for heart attack,” says Dr Hegele, who is an endocrinologist and a professor in the Departments of Biochemistry and Medicine at Western.
The study showed that commonly occurring variants in each one of the genes have a small effect, either slightly raising or lowering the particular lipid level. It’s their combination that adds up and can put people at risk for disease. For instance 39 genes showed significant association with total cholesterol, 22 with LDL, 31 with HDL and 16 with triglycerides.
The study also looked at how these common genetic variants increased the risk for heart attack. They found that the genes with the biggest impact were the ones that control LDL, the bad cholesterol. The ones that raised good cholesterol weren’t so consistent and didn’t always offer protection against heart attack. “The study provides us with good insight into bad cholesterol versus good,” says Dr Hegele. “Triglycerides, which were our particular interest, had mixed results. Some genes that raise triglycerides led to heart attack while others that also increased triglyceride levels didn’t necessarily lead to heart attack.”
The study makes it possible to develop a blood test that would directly determine whether patients carry the precise genes that put them at risk, allowing them to take precautions while they are still healthy.