Two rival teams of scientists have discovered a common genetic variation that increases the risk of heart disease up to 60 percent in people of European descent.
The scientists say they hope a test for the variant can be developed to enable doctors to assess patients at risk more accurately and to recommend early interventions like cholesterol-lowering statins and methods to reduce blood pressure. Heart disease is the leading cause of death worldwide.
The genetic variant is so common that some 50 percent of people in European populations carry one copy of it, and about 20 percent of people have inherited two copies, one from each parent. It is much less prevalent in people of African descent, the scientists said.
Carriers of a single copy have a 15 to 20 percent greater risk of heart disease, while those with two copies are up to 60 percent more likely to develop heart disease than people who have none.
The risk is even higher for people who suffer heart attack at an early age, defined as men under 50 and women under 60.
The new finding, published online Thursday in the journal Science, is one of a spate of discoveries about the genetic basis of common diseases. Last week seven new genetic variants involved in the most common form of diabetes were identified, and a batch of new genes from other common diseases is expected to be reported in the next few weeks.
These discoveries are a long-promised fruit of the $3 billion Human Genome Project, which was essentially completed in 2003.
There have been two principal approaches to scanning the genome for disease genes, which are culminating in photo-finish results by the proponents of each method.
One competitor is DeCode Genetics, a private company based in Reykjavik, Iceland, that has used the comprehensive health care records and known genealogy of the Icelandic population to track disease. DeCode has dominated the gene-finding field for the last several years.
DeCode’s rivals are medical researchers based at universities in the United States and Europe. They have made a slower start because, without an Icelandic-type data set, they have had to wait for construction of the HapMap, a survey of common genetic variations on the human genome in Africans, Asians and Europeans. These common variations, known as SNPs or “snips,” are thought to be the genetic basis of the common diseases.
Both sides have been greatly helped by a technical development, the construction by companies like Affymetrix and Illumina of instruments known as microarrays or chips that can now detect up to 500,000 snips. With the chips, the genomes of patients with a disease can be compared with those of healthy people, allowing snips that seem associated with the disease to be identified.
This week’s reports on heart disease come from DeCode and another academic consortium, led by Dr. Ruth McPherson of the University of Ottawa Heart Institute and Jonathan Cohen of the Southwestern Medical Center at the University of Texas in Dallas.