DNA analysis holds some answers, but not every claim is credible
DNA analysis holds some answers, but not every claim is credible

By David Zizzo

Published: May 6, 2008

Once upon a time in the Tuscany region of what would someday be known as Europe, a woman struggled to survive the Ice Age. Seventeen thousand years later, here I am — her direct descendant.

At least that's according to the inside of my cheek, and to a company in England that analyzed DNA from samples collected on a cotton swab that I rubbed in there. Using my personal mouth mucus, Oxford Ancestors concluded Tuscany is where I hail from — at least the maternal part of my lineage can be traced back to there. And to a particular woman, Tara, as Oxford has named her.

Oxford analyzes mitochondrial DNA, which is passed directly from mother to daughter and changes very little over long periods. The company says the maternal heritage of each of the 30,000 people whose DNA it has analyzed — and presumably all living people — traces back to one of 36 women who lived from 15,000 to 45,000 years ago.

Armed with information such as this, some people go to great lengths and expense to travel to their identified areas of origin, make contact with other related descendants or otherwise connect with their roots.

Such extreme genealogy is one of the more innocuous effects of the burgeoning worldwide industry of DNA analysis. With new DNA markers being identified all the time, many companies have begun offering DNA analysis directly to the public for many purported purposes, from determining your predisposition for disease to your athletic prowess to the diet you should eat.

Navigenics, for instance, says it will screen for various cancers, Crohn's disease, diabetes, glaucoma, heart attack, lupus, macular degeneration, even obesity and restless leg syndrome. The DNA Diet offers DNA testing that will "determine which diet program best suits your unique biochemical make up.”

CyGene Laboratories claims its "Optimum Athletic Performance DNA Analysis” can tell you what form of training will give you "a better results-oriented work-out.”

DNA analysis is a powerful tool, Brandt Cassidy said. But to say it can do all these things is stretching the technology and the credibility of the science behind it.

"There's a huge debate going on,” said Cassidy, director of operations for DNA Solutions Inc., an Oklahoma City company that performs DNA tests for human paternity and for identification of deer, cattle and other animals. He said some critics are urging more oversight by the Food and Drug Administration, which has acknowledged there could be problems.

"Be wary of claims about the benefits these products supposedly offer,” the FDA said in its pamphlet "At-Home Genetic Tests: A Healthy Dose of Skepticism May Be the Best Prescription.”

Some DNA markers, or unique DNA sequences, have proven scientific track records. They're consistent flags that indicate any person who has them is predisposed to certain conditions, such as deadly Huntington's disease, Cassidy said. But many companies that market "direct-to-consumer” DNA tests offer them with claims that have not been adequately explored or substantiated, he said. And that can be dangerous.

For example, Cassidy said, after early studies found that women with a particular mutation in the BRCA1 or BRCA2 genes had a 90 percent chance of developing breast cancer, some women told they had the mutation rushed to have radical double mastectomies.

"They were so certain they were going to get breast cancer, they went ahead and had them,” he said.

Turns out, however, that those early studies looked only at women who were of Ashkenazi (Eastern European) Jewish background. After later studies on a wide range of women, Cassidy said, "the association dropped down to less than 5 percent.”

DNA is absolute only in excluding you from a group, association or predisposition. DNA studies identify only associations with a disease or outcome, not causes of those diseases or outcomes, Cassidy said. So, whether a particular disease or predisposition will appear in a particular person depends on many things, including family history, lifestyle and environment.

"It's most likely a multitude of factors,” Cassidy said. "Your DNA is just one of the factors.”

Another shortcoming of "over-the-counter” DNA tests, many available online from "virtual genetics clinics,” is that they seldom include counseling or guidance by medical professionals — particularly those without conflicts of interest such as profiting from the tests themselves. Without counseling, Cassidy said, a consumer might not learn how valid the connection is between a genetic marker and the disease, tendency or predisposition it's supposed to reveal.

"They may not understand the limitations of the science,” he said.

So, for now, if you venture into the DNA zone, do your homework and ask a lot of questions. And not just "Where is Tuscany?”

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