TechBlog

There are those who like to believe that the future of life on Earth will continue as it has in the past, but unfortunately for humanity, the natural world around us does not care what we believe. But believing that we can do something to change our situation using our knowledge can very much affect the environment in which we live.

Perhaps an even greater problem than scientific literacy, is that almost every aspect of our modern society is geared toward only dealing with problems after they have occurred, rather than focusing on prevention. We have a visceral response to tragedies, to wars, floods, disease, and famine because we can see the problem and see the need to correct it. A much more difficult approach for societies is to use our intellectual capacity to understand the possibility of preventing wars by not invading countries but using diplomacy, or repairing infrastructure before bridges and dams fail, or preventing diseases by changing our diet.

Medicine and health care are areas that desperately need to move toward a preventive philosophy. We need to understand that it is far more cost effective, with better life outcomes to prevent diseases rather than treat them after they occur.

The cost of health care is one of the fastest growing expenses. In 2005 total US health expenditures rose 6.9% - twice the rate of inflation. Total spending was a staggering $2trillion. US health care spending is expected to increase at similar levels for the next decade reaching $4trillion in 2015. That’s 20% of GDP. But all this money does not seem to guarantee the highest quality health care. The World Health Organisation in 2000 ranked the US health care system as 1st by expenditure but only 72nd on health. In contrast the UK was 26th by total expenditures and 24th on health.

If we take a look at the cost burden of just one disease, diabetes, the figures are astounding. Diabetes is a disease that when poorly managed leads to serious complications such as heart disease, stroke, blindness, kidney failure, and nerve disease.

According to the US Centers for Disease Control, the total cost of diabetes to US society is $132billion each year. The average annual health care costs for a person with diabetes, is over five times that of someone without the disease. In the UK it is estimated that 9% of the annual NHS budget or over £5.2billion goes to diabetes care. Many studies have shown that simple preventive measures such as a healthier diet and moderate exercise such as walking can lead to dramatic reductions in the rate of disease onset and can eliminate or greatly reduce the incidence of complications.

Preventative medicine is the only way forward that I see for lowering the cost of health care other than the unacceptable approach of denying access. One of the keys to preventative medicine will be an understanding of our genetic risk for future diseases along with a greater understanding of the corresponding environmental influences of disease.

Just three months ago in September, we published the first complete human genome sequence and now it is available to all on the internet. The human genome comprises all the genetic information that we inherit from both of our parents in the form of 46 chromosomes, 23 from each parent. Chromosomes are in turn long stretches of DNA which is composed of four different chemical letters known simply as A, T, C and G. Our genome has six billion of these genetic letters. The genome we published contained both sets of chromosomes from each of my parents. I say my parents because it was my own genome that was sequenced and published.

I chose to decode my DNA because in the complex debate concerning deterministic views of genetic outcomes and the fears that many have voiced about revealing all their genetic secrets. I as a leader in this field, wanted to show that we don’t have to fear our genetic information. Our genetic code is not deterministic and will provide us very few yes-no answers. It will, however, provide probabilities concerning outcomes that we will eventually be able to influence. It seemed far better to me to use my own genome, rather than trying to convince anyone else that it was ok for them.

One of the more exciting findings from our study is that any two humans differ from each other by about 1-2%, not the 0.1% that we thought was the case when we sequenced the first draft of the human genome earlier in the decade. This data is much more comforting as it is clear to me that we are all much more individualistic than previously thought. One of the key questions that I frequently get asked is what have I learned from my genome and is there information that I can do something about?

Let me give you a few examples to illustrate some of what I have found. For example, like many people, I reach for my inhaler in smoggy conditions. Genetics contributes to this susceptibility and researchers have focused on a certain family of enzymes that help detoxify everything from carcinogens to pharmaceuticals. There is a gene that is associated with the ability to degrade environmental toxins, however nearly half of the Caucasian population lacks that gene. In my own genome I found only one copy that I received from one parent and none from the other, so perhaps that is why I am more susceptible to environmental toxins.

As a depressing bonus, given its detoxifying role, this genetic deficiency may make me more susceptible to particular chemical carcinogens, and there is an association with lung and colorectal cancers.

From my genome I also became aware of genes that confirmed my increased risk for heart disease. The most common cause of heart disease is atherosclerosis, in which calcium, along with fats and cholesterol, collects in the blood vessels to form plaques, which can trigger a heart attack or stroke. One gene called APO E is responsible for regulating levels of certain fats in the bloodstream. Variants here have been linked with heart disease and also to Alzheimer’s disease. Both of these could be in the cards for me. Fortunately, by reading my own genome, I have a chance to overcome my genetics by making changes in my diet and exercise. I am also taking a statin, a fat-lowering drug, as part of my preventative medicine paradigm. Statins also shows some hints of prevention of Alzheimer’s disease.

Hundreds more genes are linked with coronary disease, from heart attacks to high blood pressure and narrowing of blood vessels. My genome carries lower risk versions of some genes and higher risks versions of others, but it will take time for us to understand the complicated way they interact with each other and how to predict a true risk profile.

However, one genetic change that probably lowers my risk for a heart attack is associated with my body’s ability to rapidly metabolise caffeine. I drink many cups of coffee per day but fortunately, I carry the rapid metabolising version of the gene. Some genes only become harmful in combination with a certain lifestyle - drinking coffee, tea or other drinks with caffeine. Some individuals carry a mutation that slows down caffeine metabolism and, as a result, increases an individuals’ risk of having a heart attack on drinking tea or coffee. A study of around 4,000 people showed that the risk of heart attack increased 64% with four or more cups of coffee per day, compared with patients who drank less than one cup per day. However, the corresponding risk was less than 1% for individuals, who like me, had two copies of a rapid metabolising version of the gene. These genetic differences may explain why many studies looking at the association between caffeine consumption and heart attack risk have been inconclusive, because we are not genetically identical and do not all respond in the same way.

These are just a handful of illustrations that hint at the type of information that will be possible for all of us in the near future.

At my institute we are now scaling up to sequence the genomes from 10,000 people. This will provide a massive and powerful database, particularly when linked with clinical records and life outcomes. At that stage, we will have a much clearer view of the genetic basis of humanity.

I feel that new laws are needed to prevent an individual’s genetic code from being used as a basis of discrimination in education, employment or access to health care. The genetic code will give us probabilities about disease risk and the ability to understand environmental factors linked to genetics. Will governments, businesses and insurance companies pay the smaller amount in advance to prevent disease? Or will we be locked into the current system of treating only what we can see?

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