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The Call-In: DNA Testing


Time now for The Call-In - last week, we asked you about your experiences with DNA testing kits. Hundreds of you responded.

UNIDENTIFIED WOMAN #1: And it found a link between her and my father.

UNIDENTIFIED WOMAN #2: We have since learned that I am the grandchild of a successful sperm donation.

UNIDENTIFIED WOMAN #3: I finally confirmed what I had always suspected but no one in the family would talk about.

GARCIA-NAVARRO: The kits are being used now by millions of people to find out more about their heritage or health. But Maria Antonia Colon was looking for answers about her ancestors. Colon is 45 years old. And she lives in Sacramento, Calif., but she grew up in a Puerto Rican neighborhood of Chicago.

MARIA ANTONIA COLON: We participated in the Puerto Rican Day Parade. All my friends were Puerto Ricans or Mexicans. So we were surrounded by the culture. And I felt very much a part of it.

GARCIA-NAVARRO: Colon's mom is white. But she felt connected to that Puerto Rican culture through her dad. That was until someone planted a seed of doubt about whether he was really her biological father. They told her her real dad was Polish. And because she's tall and pale, she worried it might be true.

COLON: For many years, I carried this burden of believing that I wasn't who I was and that my cultural identity really wasn't mine and that I was just faking it. That propelled me to want to do DNA testing. Although, I was reluctant for some time because I was afraid of what I might find - that, actually, I was Polish rather than being Puerto Rican.

GARCIA-NAVARRO: She ordered three different home DNA testing kits, sent off her samples and waited for the results to arrive.

COLON: It was such a beautiful thing when I opened the report and I saw immediately that someone in my family must come from one of these places. And it listed Cuba, Dominican Republic and Puerto Rico. And I just burst into tears, tears of joy.

GARCIA-NAVARRO: For Maria Antonia Colon, the genetic test resolves a question that was at the heart of her identity. But Dr. Siddhartha Mukherjee says we need to consider the limitations of these tests.

SIDDHARTHA MUKHERJEE: You know, the home tests are in a very early phase of their development and of our understanding of what they can and cannot tell us.

GARCIA-NAVARRO: Mukherjee is an oncologist and author of "The Gene: An Intimate History." He told me there are two ways of addressing that question.

MUKHERJEE: One of them is about the past. That's about ancestry. The tests on your genome can tell you a little bit about your ancestry, perhaps. And I think that might be useful. It's mostly a curiosity satisfier. The second kind of question is what can they tell you medically? What can they tell you medically about your future?

There, I think we are in a very, very early phase. We - there are certain, you know, single gene changes that can be identified. Their predictive value for your future development of a disease is pretty minimal - remains pretty minimal. You know, this is a kind of situation where more data produces more data. And as we have more and more people, we will hopefully begin to see a time when there will be real future diagnostics about an individual's future that will be possible. But that is not possible at this time. We just don't have enough data. It's just too early in the game.

GARCIA-NAVARRO: I'd like to pick apart one of the things and focus on people taking these tests for looking at their past, their ancestry. What can they tell us about race and ethnicity? And what should people think about what they learn?

MUKHERJEE: Well, the first thing to know is that the Victorian definition or really the pre-scientific definition of race is a flawed concept - not just flawed but deeply flawed concept. And that's just to remind us that what we used to categorize as the broad races was a - it was an inheritance that we acquired from basically anthropologists who were trying to divide human populations very widely but didn't really fathom the complexity of human genomics.

Here's the point. There is a geographical reality to the fact that human beings originated in one place several hundred thousand years ago and then moved geographically from one place to another - migrated. And, of course, people who migrate - there will be a familial relationship between, you know, if you came closer from that migration versus if you departed further and further away. So that geographical reality remains genetically real. But the Victorian idea of the race which depends on relatively arbitrary characteristics such as skin color - those were artificial categories. And the real categories are, in fact, human migratory patterns that have developed over the last 200,000 odd years.

GARCIA-NAVARRO: May I ask you what can we do now already? I mean, we already know through genetics about their predisposition for Alzheimer's.

MUKHERJEE: Well, you know, Alzheimer's is a good example. There are a few gene variants which will clearly increase your risk for having Alzheimer's disease. But, in fact, if you look at most people with Alzheimer's disease, it's a complex genetic cascade, genes that are playing what I might describe as nudge effects as opposed to shove effects. Our understanding of genetics was, for the longest time, dominated by these shove genes, these single genetic mutations - variations that would have a disproportionately high effect on our capacity to develop a disease. We're now entering an era where we're beginning to decipher these nudge genes.

GARCIA-NAVARRO: So what does that tell us about where this is going?

MUKHERJEE: In the distant future, maybe in the near future, we might get to a place where you might be able to predict the risk of an individual developing cancer. We might be able to predict your real risk of having a heart attack at age 40. That's valuable information. We're not there yet, but we need lots and lots of data to get there. But once you're there, you need to make some extraordinarily important ethical choices.

Who should have this information? Should it be publicly available? If we keep dividing people up this way, how can you imagine insurance? I mean, you know, if every human being - if you and me, if every person in your studio was to have attached to them finer and finer grains of genetic risks - you know, 40 percent risk of getting breast cancer, 65 percent risk of having a heart attack at age 40 - how can we possibly imagine insuring these people under individual commercial insurances? I can't imagine a way. So, ironically, one of the things that's emerging from our deep understanding of human variation or human differences is a kind of plea for human equality.

GARCIA-NAVARRO: That Siddhartha Mukherjee. He's the author of "The Gene: An Intimate History." Thank you very, very much.

MUKHERJEE: My pleasure - thank you so much.

(SOUNDBITE OF MUSIC) Transcript provided by NPR, Copyright NPR.

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