Empowering prevention*

The effect of the identified genetic risk variants on chromosome 9 appears to be in addition to and independent of other known risk factors such as obesity, hypertension, diabetes or elevated blood cholesterol.When it comes to coronary heart disease and MI, understanding risk is the first step in empowering prevention.

Heart disease is the leading cause of death for both women and men in western societies and coronary heart disease is the principal type of heart disease. Worldwide, coronary heart disease kills more than 7 million people each year.  In the US alone 494,392 people died from coronary heart disease in 2002. In 2002, age–adjusted death rates for diseases of the heart were also found to be 30% higher among African Americans than among Caucasians. In 2006, heart disease in the US was projected to cost more than $258 billion, including health care services, medications, and lost productivity.  According to numbers for the years 1999 – 2002 the prevalence of the leading known, but at the same time manageable risk factors for coronary heart disease among persons 20 years and older, were:

In 2003, approximately 37% of adults reported having two or more of the above six risk factors of cardiovascular diseases.  Studies among people with heart disease have shown that lowering high blood cholesterol and high blood pressure can reduce the risk of dying of heart disease, having a nonfatal heart attack, or needing heart bypass surgery or angioplasty.

As a physician, you likely have numerous patients with well known risk factors for coronary heart disease, who need to stop smoking, lose weight, get more exercise, improve their diet, and comply with your recommended blood lipid and/or blood pressure lowering medication. Moreover, your efforts to get your patients to change their lifestyle and address known risk factors for coronary heart disease are most likely not always successful. Additional information on which of your patients might also be at increased genetic risk gives your advice added weight and relevance. For your patients the information should increase their incentive to implement and stick to lifestyle modification regimens and prescribed medications that can reduce their chances of getting MI. It can be argued that it is the patient's right to know about all of his/her relevant risk factors. This is especially relevant in light of the difficulties patients are having with adhering to diet and weight recommendations and because of the physician's role in reminding them of the importance of compliance to his/her recommendations.  It is in this context where knowledge of the presence of the extra genetic risk is most important for both parties.

deCODE MI™ may provide an important new means of identifying those who are at elevated inherited risk of developing coronary heart disease and MI independent of other risk factors. TO:  deCODE MI™ detects versions of  SNPs (single nucleotide polymorphism) – single letter variations in the sequence of the genome on chromosome 9 and have been linked to increased risk of MI. These risk variants are the first widely-replicated, common genetic variants ever found to associate with substantially increased risk of coronary heart disease and MI as public health problems.

In deCODE’s study, published in Science in June 2007, and which has been validated in 10 independent populations covering thousands of people, 20-22% of the general population have been shown to carry two copies of the risk variants.  In other words, having two copies of the risk variant - a positive result for the deCODE MI™ test – has been shown to correspond to an approximate 2 fold increase in likelihood of early onset MI and 1.6 fold risk for MI regardless of age of onset. The risk variants tested for by deCODE's MI test are the “G” allele of SNP rs10757278 and the "C" allele in SNP rs1333049 located in the vicinity of the tumor suppressor genes CDKN2A and CDKN2B on chromosome 9p21, whose proteins encoded called p16INK4a, ARF, and p15INK4b - play a critical role in regulating cell proliferation, cell aging and senescence, and apoptosis in many cell types. These are all important features of atherogenesis, the underlying cause of coronary heart disease and MI. Despite their vicinity to these genes the mechanism whereby the genetic variants exert their effects in the pathogenesis of MI and if that is even through the protein products of CDKN2A and CDKN2B, remains to be elucidated.

Despite our current lack of understanding how the deCODE MI variant mediates its effect the deCODE MI™ test provides a new means to help physicians to decide which individuals, who may already are at significant risk of developing coronary heart disease and/or MI, they wish to treat more aggressively through lifestyle change and/or through drug treatment of associated risk conditions.

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