Sunday, January 2, 2011

Blog #24 What You Got from Grandma that Wasn't in the Will

There has been a lot of talk in the medical media lately about genetics. After reading and listening to a number of interesting pieces there seems to be two main points….

1. Genes are not nearly as important/predictive as we have been told
2. Genes are significant in more subtle and profound ways then previously thought.

Media messages are nothing if not abundantly clear.

According to one article (The Great DNA Data Deficit: Are genes for disease a mirage? By Jonathan Latham and Allison Wilson in The Bioscience Resource Project, Dec. 8, 2010), knowing the make-up of your genes helps you predict your chances of getting an illness at about the same accuracy rate as reading an insurance company chart with population statistics of getting a disease and finding your demographic. Forty year old, normal weight black female who does not smoke? You can look up your group on a disease risk chart and find your chances of getting dementia and save yourself the trouble of cracking your personal genetic code.

Francis Collins, renowned geneticist and the head of US National Institutes of Health (NIH) encourages everyone to have their genetic disease susceptibility tested anyway. He had his own mapped and it was such a profound experience that he wrote a book. His most significant personal discovery was that instead of the average risk of developing diabetes given that he was a white male (23%), he had a 29% chance of getting the disease. Otherwise his likelihood of getting cancer, heart disease and dementia was like everyone else. The book must be very short.

Consequently, the gene mapping industry is in trouble. Most people who have done disease risk gene testing discover the same shocking fact: they are average. The exception is those with rare genetic disorders like cystic fibrosis. Of course these individuals by definition are “rare”. With consistently underwhelming findings, the monetary returns that were supposed to be generated from personalized gene mapping technology are looking bleak. At the moment, it looks like you would be better off investing in soap futures or uranium mining.

Genes are not as important and predictive as we have been told because one of the unexpected results of the human genome project was the discovery that DNA is not the most important part of the chromosome. DNA represents half of what is in the chromosome and the only material scientists were interested in until they realized how inert DNA is. Every cell has all the DNA needed for making everything in the body. In addition, there is enormous similarity between the DNA of human and all other animals. We have many fewer genes than scientists expected to explain human diversity let alone the bigger variation between people and fruit flies. DNA turns out to be mostly generic blueprint material. In other words, most of the DNA we carry looks like everyone else’s including monkeys and I don’t mean your brother-in-law.

What regulates and individualizes the DNA? The other half of the material that scientists thought was not important. Yes. It turns out that regulation is where all the action is and few scientists realized this until all the DNA was mapped and turned out to be stunningly generic. (For more on this topic see Dr. Bruce Lipton’s, The Biology of Belief.)

Which leads to point two about the ways genes may be more important than we thought. The DNA might be similar but the controlling proteins and regulation is wildly diverse. Regulation can be affected by your environment, stress, thoughts and your diet. The results are profound and can be so long lasting that what your grandmother or great grandmother ate or experienced while she was pregnant might be effecting how you are expressing your genes today. There is even emerging evidence that your grandfather’s health at the time of conception (try not to think about that part) could shift your disease risk today. This emerging field is called epigenetics and it is mind blogging.

Imagine the implications of this study. Scientists took some male rats and made them fat by feeding them a high fat diet similar to what we Americans eat today. The fat rats, who had symptoms of type 2 diabetes, were bred with non-overweight females. The pups did not become overweight (because of how they were fed) but a lot of them developed type 2 diabetes anyway! Ditto for the next generation.

We already know that pregnant women on starvation diets (due to famine or war) have children and grandchildren with much higher rates of obesity. The fetus makes decisions about gene expression in utero based on the kind of world it thinks it is coming in to. This early gene regulation has life long (and after) ramifications.

So, what practical application can this information have? The results of epigenetics walked into my office in the form of eleven year old, Danika. To be continued…….

1 comment:

  1. Hi Kelly

    I am one of the authors of the Great DNA Data Deficit article you mention.
    That genes dont cause disease is a hugely important finding but epigenetics is not a likely substitute. Firstly, epigenetics is not genetics in the same way that inheriting money from your parents is not genetics. There are no permanent DNA changes. Secondly, the biological significance of epigenetics is almost pure speculation. There is hardly any data. For example in the study you mention there is no real evidence that epigenetics (in its proper sense of chemical and reversible modifications of DNA) was responsible for the effects seen. In other words, this finding is being massively hyped. Why?

    As we wrote, the genetic hypothesis is failing catastrophically and biologists are scrabbling for a substitute so they can avoid admitting as much. Epigenetics, from the data available, is never going to be that substitute, but plenty of people seem to be hoping it will be.
    PS The article is at: