TOPICS > Science

Geneticist Discusses Decoding His Own DNA

September 4, 2007 at 6:45 PM EDT
LISTEN SEE PODCASTS

TRANSCRIPT

JEFFREY BROWN: How much of who we are comes from our mother’s genes? How much from our father’s? And how do they interact to create the complex beings we are?

In 2000, scientists took their a landmark step in decoding the human genome, sequencing the order of billions of letters of DNA, using a blend of data from people with differing backgrounds. Now researchers have gone further by detailing the entire genetic makeup of one person and looking at the genes of both mother and father.

That one person is the scientist who published the work, geneticist Craig Venter.

Welcome to you.

CRAIG VENTER, Geneticist: Thanks.

JEFFREY BROWN: Explain to us a bit more about what you have done here and how it differs from what was done earlier.

CRAIG VENTER: Well, in 2000, there were two different versions of the genome. The government-sponsored one took individual clones from, I think, 270 different people and put a composite together of what was a haploid genome, basically half of the genome.

At Celera, we did five different people. Mine was 60 percent of that sequence. But when we did the computer assembly of that, we, by definition, subtracted out a lot of the differences trying to get a consensus assembly, so both were flawed by what we know today, where we now have the complete genome of both sets of chromosomes that I inherited from my parents.

JEFFREY BROWN: And the value of looking at one person — you — is what?

CRAIG VENTER: Well, the value will only come by looking at each one of us. This is just the very first step. I think next year we’ll probably see 30 to 50 individual genomes done, and hopefully a major escalation from there. But we had to start with one as a reference, and we built on the data that was generated earlier at Celera.

JEFFREY BROWN: So this does give us a clearer view of what comes from our mother and what comes from our father?

CRAIG VENTER: Well, it gives us a view of how much greater our complexity is than was previously thought.

JEFFREY BROWN: In what way?

CRAIG VENTER: Well, so when we compare — basically, each of us have two haploid genomes that we get from each parent. And it turns out even my two sets of chromosomes differ from each other by about five to seven times more than we thought before.

But if we were going to compare my genome, my two sets of chromosomes, to your two sets, human variation could be as much as 1 percent to 2 percent. So we went from 99.9 percent to maybe 99 percent or 98 percent. This is almost as much as we thought differed between humans and chimps, so it tells us that we differ a lot more.

I think this is good news that we’re much more individualistic. As an individualist, I like that news.

Different genetic makeup

Craig Venter
Geneticist
Instead of just all of us having the same sets of genes and just looking at single-letter changes in those genes to explain human biology, we now know that we don't have all the same sets of genes.

JEFFREY BROWN: All right, well, now you were the subject here, so use your example to help us understand what this is about. I mean, what did you find out about yourself?

CRAIG VENTER: Well, instead of just all of us having the same sets of genes and just looking at single-letter changes in those genes to explain human biology, we now know that we don't have all the same sets of genes. An example is, from one of my parents, I inherited a gene that detoxifies environmental toxins. My other parent didn't have that gene. In fact, it turns out maybe a third of Caucasians have no copies of this gene.

That's a very different view than we thought before of just -- it was single-letter changes. So we don't all have the same sets of genes. And even when we do, about 40 percent of my genes have major variations in one of the copies that's not in the other.

So the complexity of trying to explain our biology based on having two different structures of these genes and the variety of them makes it a lot more challenging, but I think it will be a good news in the end. It will actually get down to the reality of what we can say and what we can't.

JEFFREY BROWN: Do we know how the two interact? Can your mother's genes counteract something that is found in your father's genes? Or can they come together and create something that gives us a risk for something altogether new?

CRAIG VENTER: Well, in fact, there's exchanges of DNA between our parental chromosomes. They do have some crossover and exchange. And then there's other events called imprinting, where we know either the mother or father's gene has a far stronger influence than you'd predict from just genetics.

So there's a lot more to it than just even knowing the sequence. But we can really start to see these events for the first time and even relate them back to either side of the family.

Tracking inherited traits

Craig Venter
Geneticist
This is a next big step towards going in that direction, because now we see what it's like in one individual. Our goal is to maybe, over the next five years, get as many as 10,000 different complete human genomes.

JEFFREY BROWN: And we were talking before we went on here about the game that is played in a lot of people's homes -- certainly in mine -- about who gets the blame or the credit for the kids, right, the brains, or the looks, or the inability to do homework, or anything like that. Are we almost at a point where we could figure out things like that?

CRAIG VENTER: Well, we're getting much closer. This is a next big step towards going in that direction, because now we see what it's like in one individual. Our goal is to maybe, over the next five years, get as many as 10,000 different complete human genomes.

Then we can actually start to answer some of these questions, not only what came from what parent, but what part genetics actually plays in behavior, in personality, in different diseases, things that we know have environmental components and we know have genetic components. We have to have very large populations to do these comparisons with, but this is important even in understanding the risk for disease.

Most genetic components of disease aren't small changes in single genes that are linked to a gene for this disease. It's going to be the minor variations in our genome that really tell us what our risks are.

The cost of the genetic research

Craig Venter
Geneticist
It takes us in a step of public accessibility of this information versus only being in secret databases. And it sends an important message to the public: You don't have to fear your genetic information.

JEFFREY BROWN: So how close are we now to a point where this becomes more common, where average folks could go and get their genetic makeup?

CRAIG VENTER: It will definitely happen within five years, where this exponential change in the cost. The government genomes were on the order of $3 billion to $5 billion. It's now down to some technology they're claiming they could do a whole genome for maybe $100,000. That will be a fraction of that, hopefully, within a few years.

Through the X PRIZE Foundation, we have a $10 million prize for scientists that get the technology down to maybe $1,000 for a genome. It's going to change rapidly, and we hope that tens of thousands of people start contributing their genomes.

JEFFREY BROWN: Now, you have long been an advocate for this, for individuals moving in this direction and making public the information, right?

CRAIG VENTER: Yes.

JEFFREY BROWN: What's the benefit?

CRAIG VENTER: Well, the benefit is, obviously, to all of science in helping to interpret this information, but it also helps people become less afraid of this. I think when the Genome Project started, people were sort of taught, "Genetics is fearful. You don't want that information." And it came from a few very rare genetic disorders that you could predict from the genome.

It turns out, those are not at all the rule of what we can find. And myself and now, fortunately, others, Jim Watson, who co-discovered the structure of the DNA helix, has recently got his genome sequenced. And I think that will be published soon.

It takes us in a step of public accessibility of this information versus only being in secret databases. And it sends an important message to the public: You don't have to fear your genetic information.

Privacy concerns with DNA

Craig Venter
Geneticist
This information will be probably more predictive and more useful. ... The insurance industry seems very divided on how and if to use the information, but they've been using surrogates for genetic information for a long time.

JEFFREY BROWN: But, you know, of course, many people have talked about some of the concerns, privacy concerns, if this is out there, for potential employers or insurers who would see your genetic predispositions and possibilities, potentials for discrimination on various grounds. That's still out there.

CRAIG VENTER: It is very much out there, and it is an important issue. Whether it's scientifically based or not, discrimination is using -- doesn't have its basis in science. There's been legislation that's been pending for a very long time and a genetic discrimination bill that would actually prevent employers from using the information.

Insurance companies use genetic information all the time. They do it in the form of taking your blood pressure, giving you an EKG, or taking your family history.

JEFFREY BROWN: You'd be giving them quite a bit more, wouldn't you?

CRAIG VENTER: Well, this information will be probably more predictive and more useful. People with a family history of heart disease pay more for their life insurance than people that don't. If you smoke, you pay a higher premium. So I think, you know, the insurance industry seems very divided on how and if to use the information, but they've been using surrogates for genetic information for a long time.

JEFFREY BROWN: We only have about 30 seconds, but this was sort of famously a race that you've been part of to map the human genome. Is the race continuing? What's next?

CRAIG VENTER: It was a race up until the year 2000. And we settled that at the White House with President Clinton. I said it was a race to the starting line. It's amazing. In seven years, we've gotten past the starting line but not very much further. I think these next steps are going to be much faster in their pace of change.

JEFFREY BROWN: All right, Craig Venter, thanks very much.

CRAIG VENTER: Nice to be with you.