MIND WEEK: Deepak Chopra & Rudi Tanzi Explore the Role of Our Genes in Diseases of the Mind

Contrary to public perception, there is no such thing as a “disease gene.” All genes are “good” and provide a normal function needed by the body. It’s the variants they harbor that can bring problems. On the positive side, some mutations increase resistance to disease. A few rare family strains, for example, have given almost total immunity to heart disease. No matter how much fatty food is in their diet, the cholesterol isn’t converted into blood fats that line the coronary arteries with plaque. Geneticists have sought out these isolated populations to discover which variant might have gifted them with resistance to heart disease. By the same token, there are small, rare populations in which presenile Alzheimer’s disease affects almost the entire family line. They, too, must be studied in an attempt to discover if a genetic signature is responsible for such a bad outcome.

Rudy was fortunate to be intimately involved with the earliest pioneering events of the current genetics revolution. When he and his colleague Dr. James Gusella were still in their early twenties, carrying out the first mapping of the human genome at Massachusetts General Hospital, they became the first researchers in the world to locate a disease-causing gene by tracking natural DNA variants in the genome. In their landmark study, they were able to show that the gene for Huntington’s disease resides on chromosome 4. Huntington’s disease is a fatal disorder in which no clues about the cause were previously available.

[Good Genes, Bad Genes and Super Genes: How to Harness Your Genetic Potential]

9780804140133Some variants are common ones, being present in more than 10 percent of the human population, while others are rare, isolated mutations. A genetic variant can predispose you to certain diseases or behaviors, which is why research focuses so intensely on the genetic contribution to Alzheimer’s or depression. Other variants do nothing at all, at least not so far in our evolution. Your personal DNA “fingerprint” is based on the set of variants you inherited. These determine both the functioning and structure of the hundreds of thousands of different types of proteins in your body.

The number of gene variants that give you a fixed characteristic like blue eyes or blond hair are known as fully penetrant gene variants, and they are in the vast minority, as few as 5 percent of the total. But, in the vast majority of cases regarding health and personality, your genetic destiny is not set in stone. Genes are only one component of the almost infinite interplay of DNA, behavior, and the environment.

This fact was underlined by a 2015 study on autism published in the journal Nature Medicine. Autism is a baffling disorder because there is no single kind of autism, but rather a wide spectrum of behavior, one that Rudy has worked on extensively over the course of his career. The mass media image of an autistic child portrays a totally withdrawn state in which the child hardly reacts to any outside stimuli. Totally lost in himself, he may rock back and forth or “twiddle” with repeated, robotic gestures. Emotions are stunted or nonexistent. The parents are desperate to find a way to break through the shell.

But in some families there are two autistic children, and more often than not, the parents say that their behavior is very different. The new study, which looked at the genes of autistic siblings, confirmed this impression. Researchers looked at eighty-five families in which two children had been diagnosed with autism. It’s possible, through techniques known as genome-wide association screens and whole genome sequencing, to look at millions of DNA variants in someone’s genome. The study targeted 100 specific variants that have been genetically associated with a greater risk of being autistic. To everyone’s surprise, only about 30 percent of the autistic siblings shared the same mutation in their DNA, while 70 percent did not.

[Can Alzheimer’s Be Beat Through Conscious Aging? What a New Study Shows]

In the shared group, the two autistic children behaved more or less alike. But in the unshared group, the 70 percent, their behavior was as different as any two brothers or sisters. What this suggests is that autism is unique because each person is unique. Even if scientists examined the genome of thousands and thousands of autistic children, it would be extremely challenging to determine the biological basis of the disease.

Unfortunately, not being able to predict autism in advance brings us back to a state of uncertainty. The chances of having two autistic children in a family of four or more is remote, about 1 in 10,000. As reported in the New York Times, a Canadian couple who already had one severely autistic child and one child with no developmental problems went to the doctor’s with their wish to have a third child. What was the risk that the new baby would be autistic? Hospitals examine the genome of the oldest affected child to arrive at a prediction. In this case, the couple were told that the chances of having another autistic child were slim, and in any event, if the child were autistic, it wouldn’t necessarily be to a severe degree.

But, in reality, the new baby, which the couple decided to have, did develop severe autism. And the couple report that their two autistic children don’t behave alike. One is outgoing enough to run up to strangers, while the other holds back. One loves to play with computers; the other has no interest. One runs around, while the other prefers to sit in one place.

This is the outcome of diversity. No matter how many genetic samples you take from a family line, the next baby to be born will be largely unpredictable, not just in terms of the risk of autism but in general.

[Read Maria Shriver’s latest ‘I’ve Been Thinking’ essay]

While genes clearly determine some things, like the onset of some rare forms of disease, most of the time the gene variants that we inherit merely confer a susceptibility toward a disease. The same can be said about genetic predisposition to certain behavior or personality types. The bottom line is that what we do, what we experience, and how we view the world, along with what we are exposed to in our environment, strongly influence the actual outcome of the genes we inherit. No one can put a precise number on how much influence you can exert on your gene expression. But there’s no longer any doubt that your influence is important, because it’s in play all the time.

 


Excerpted from SUPER GENES: UNLOCK THE ASTONISHING POWER OF YOUR DNA FOR OPTIMUM HEALTH AND WELL-BEING Copyright © 2015 by Deepak Chopra, M.D. & Rudolph E. Tanzi, Ph.D. Published by Harmony Books, an imprint of Penguin Random House LLC.

{Image credit: Pixabay}

About the Author

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Deepak Chopra M.D., co-author of Super Genes: Unlock the Astonishing Power of Your DNA for Optimum Health and Well-Being, is a pioneer of integrative medicine and the author of more than 80 books published in 43 languages. Many have been New York Times bestsellers in both the fiction and nonfiction categories.Rudolph E. Tanzi Ph.D., co-author of Super Genes: Unlock the Astonishing Power of Your DNA for Optimum Health and Well-Being, is the Joseph P. and Rose F. Kennedy Professor at Harvard University and Mass. General Hospital. Dr. Tanzi is an internationally acclaimed expert on Alzheimer's disease and was included in TIME magazine's "TIME 100 Most Influential people in the World."For more information click here and follow the authors on Facebook and Twitter: @DeepakChopra and <@RudyTanzi.

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