One expert warns not to hope for too much from genome findings
HILARY BURN
News Writer
Our expectations for the potential of genetic research should not be too high, said Dr. Neil Holtzman, a professor at Johns Hopkins, in a lecture Friday at the North Central Indiana Ethics Consortium at Notre Dame.
"Genetics will advance knowledge, but its effect on health or reducing the burden of common complex diseases will not be terribly great," Holtzman said.
Even after last week's highly publized announcement that scientists have figured out the human genome sequence, they are still in the process of deciphering it. Researchers estimate that there about 30,000 genes, but, in terms of function, only a couple thousand have been identified, according to Holtzman.
As this genetic research has progressed, "revolutionary claims have been made [by both the media and the scientific community] about the ultimate impact of genetics on clinical medicine," he said
Authorities in the field promised that mapping the human genome would lead to new strategies to prevent common diseases.
Such promises eventually led to the optimism expressed in a story in The New York Times, "Genetic Code of Human Life is Cracked by Scientists." The article said the achievement "represents a pinnacle of human self-knowledge," and that understanding them holds the key to the script of the human organism.
Holtzman said that these claims are unrealistic.
"The new genetics will not revolutionize the way in which common diseases are identified or presented," he said.
Scientists and doctors are likely to succeed in their attempt to predict, diagnose and treat simple diseases that are caused by mutations in one gene, according to Holtzman. Unfortunately, these simple diseases are much more rare than complex diseases, such as cancer. These diseases depend on environmental factors and complicated interactions between several genes.
"It's not impossible, but highly unlikely that we'll be able to identify all of the genes involved in complex diseases," Holtzman said. "If we were able to do this, then maybe it would lead to genetics revolutionizing medicine. But this won't happen, at least in our lifetime."
Even if researchers were able to determine which genes were related to which diseases, the chance that somebody with certain genes gets a particular disease is not much greater than the chance that somebody without these genes will. Scientists have discovered two genes, the BRCA genes, that seem to be highly correlated with whether or not a person will develop breast cancer. These genes are exceptions, however, because it is highly unlikely that we will find such a direct correlation for many other diseases, said Holtzman.
In the case of breast cancer, having a mutated BRCA gene does not mean that the person will get the disease for certain. There are other genetic and environmental factors involved. Its predictive value is even smaller because less than 4 percent of all breast cancer patients actually have the rare BRCA genes.
Even if scientists are able to determine that having a certain gene or genes increases the person's risk of getting a particular disease, Holtzman questioned whether people would want to know or care.
"People aren't terribly interested in knowing risks that are much below 50 percent," said Holtzman. "Even if a person has a 25 percent greater chance [of getting a particular disease], they wouldn't take a drug for the rest of their life or change their lifestyle [as preventative measures.]"
This scenario is a subtle effect of genetic determinism because a person might say "It's in my genes, so there's nothing I can do about it," he said. Contrary to popular belief, a few treatments to correct or compensate for gene defects have already been developed, said Holtzman.
Despite all of its limitations, knowing the human genome will still teach us a lot, Holtzman said. Besides helping to predict, diagnose and treat simple diseases, it will also help us understand how some genes affect drug sensitivity and resistance. For example, multidrug resistance genes that reduce sensitivity to leukemia treatment have already been discovered.
"Genetics has a lot to contribute to how our cells and organs work. We should recognize this without making claims that it will revoltionize medicine," Holtzman said. "Recently we've spent more on the genetic research side and neglected other factors, but we need to think more globally."
Social smoking intervention policies, for example, have had a greater effect on decreasing the occurrence of lung cancer than any genetic discoveries to date.
"Our overall positive goal is to improve people's health," he said. "To accomplish this we might succeed better by reducing inequities in health, improving the environment, and providing adequate health care to every one than we would by investing heavily in genetics."
Holtzman is a professor of pediatrics, health policy and epidemiology at Johns Hopkins University. His article "Will Genetics Revolutionize Medicine?" was published in the New England Journal of Medicine last July.
News Writer
Our expectations for the potential of genetic research should not be too high, said Doctor Neil Holtzman, a professor at Johns Hopkins, in a lecture Friday at the North Central Indiana Ethics Consortium at Notre Dame.
ÒGenetics will advance knowledge, but its effect on health or reducing the burden of common complex diseases will not be terribly great,ÓHoltzman said.
Even after last weekÕs highly publized announcement that scientists have figured out the human genome sequence, they are still in the process of decifering it. Researchers estimate that there about 30,000 genes, but, in terms of function, only a couple thousand have been identified, according to Holtzman.
As this genetic research has progressed, Òrevolutionary claims have been made [by both the media and the scientific community] about the ultimate impact of genetics on clinical medicine,Ó he said
Authorities in the field promised that mapping the human genome would lead to new strategies to prevent common diseases.
Such promises eventually led to the optimism expressed in a story in The New York Times, ÒGenetic Code of Human Life is Cracked by Scientists.Ó The article said the achievement Òrepresents a pinnacle of human self-knowledge,Ó and that understanding them holds the key to the script of the human organism.
Holtzman said that these claims are unrealistic.
ÒThe new genetics will not revolutionize the way in which common diseases are identified or presented,Ó he said.
Scientists and doctors are likely to succeed in their attempt to predict, diagnose and treat simple diseases that are caused by mutations in one gene, according to Holtzman. Unfortunately, these simple diseases are much more rare than normal complex diseases, such as cancer. These diseases depend on environmental factors and complicated interactions between several genes.
ÒItÕs not impossible, but highly unlikely that weÕll be able to identify all of the genes involved in complex diseases,Ó Holtzman said. ÒIf we were able to do this, then maybe it would lead to genetics revolutionizing medicine. But this wonÕt happen, at least in our lifetime.Ó
Even if researchers were able to determine which genes were related to which diseases, the chance that somebody with certain genes gets a particular disease is not much greater than the chance that somebody without these genes will. Scientists have discovered two genes, the brca genes, that seem to be highly correlated with whether or not a person will develop breast cancer. These genes are exceptions, however, because it is highly unlikely that we will find such a direct correlation for many other diseases, said Holtzman.
In the case of breast cancer, having a mutated brca gene does not mean that the person will get the disease for sure. There are other genetic and environmental factors involved. Its predictive value is even smaller because less than 4 percent of all breast cancer patients actually have the rare brca gene.
Even if scientists are able to determine that having a certain gene or genes increases the personÕs risk of getting a particular disease, Holtzman questioned whether people would want to know or care.
ÒPeople arenÕt terribly interested in knowing risks that are much below 50 percent,Ó said Holtzman. ÒEven if a person has a 25 percent greater chance [of getting a particular disease], they wouldnÕt take a drug for the rest of their life or change their lifestyleÓ as preventative measures.
This scenario is a subtle effect of genetic determinism because a person might say ÒItÕs in my genes, so thereÕs nothing I can do about it,Ó he said. Contrary to popular belief, a few treatments to correct or compensate for gene defects have already been developed, said Holtzman.
Despite all of its limitations, knowing the human genome will still teach us a lot, Holtzman said. Besides helping to predict, diagnose and treat simple diseases, it will also help us understand how some genes affect drug sensitivity and resistance. We have already discovered multidrug resistance genes that reduce sensitivity to leukemia treatment.
ÒGenetics has a lot to contribute to how our cells and organs work. We should recognize this without making claims that it will revoltionize medicine,Ó Holtzman said. ÒRecently weÕve spent more on the genetic research side and neglected other factors, but we need to think more globally.Ó
Social smoking intervention policies, for example, have had a greater effect on decreasing the occurrence of lung cancer than any genetic discoveries to date.
ÒOur overall positive goal is to improve peopleÕs health,Ó he said. ÒTo accomplish this we might succeed better by reducing inequities in health, improving the environment, and providing adequate health care to every one than we would by investing heavily in genetics.Ó
Holtzman is a professor of pediatrics, health policy and epidemiology at Johns Hopkins University. His article ÒWill Genetics Revolutionize Medicine?Ó was published in the New England Journal of Medicine last July.
News Writer
Our expectations for the potential of genetic research should not be too high, said Doctor Neil Holtzman, a professor at Johns Hopkins, in a lecture Friday at the North Central Indiana Ethics Consortium at Notre Dame.
ÒGenetics will advance knowledge, but its effect on health or reducing the burden of common complex diseases will not be terribly great,ÓHoltzman said.
Even after last weekÕs highly publized announcement that scientists have figured out the human genome sequence, they are still in the process of decifering it. Researchers estimate that there about 30,000 genes, but, in terms of function, only a couple thousand have been identified, according to Holtzman.
As this genetic research has progressed, Òrevolutionary claims have been made [by both the media and the scientific community] about the ultimate impact of genetics on clinical medicine,Ó he said
Authorities in the field promised that mapping the human genome would lead to new strategies to prevent common diseases.
Such promises eventually led to the optimism expressed in a story in The New York Times, ÒGenetic Code of Human Life is Cracked by Scientists.Ó The article said the achievement Òrepresents a pinnacle of human self-knowledge,Ó and that understanding them holds the key to the script of the human organism.
Holtzman said that these claims are unrealistic.
ÒThe new genetics will not revolutionize the way in which common diseases are identified or presented,Ó he said.
Scientists and doctors are likely to succeed in their attempt to predict, diagnose and treat simple diseases that are caused by mutations in one gene, according to Holtzman. Unfortunately, these simple diseases are much more rare than normal complex diseases, such as cancer. These diseases depend on environmental factors and complicated interactions between several genes.
ÒItÕs not impossible, but highly unlikely that weÕll be able to identify all of the genes involved in complex diseases,Ó Holtzman said. ÒIf we were able to do this, then maybe it would lead to genetics revolutionizing medicine. But this wonÕt happen, at least in our lifetime.Ó
Even if researchers were able to determine which genes were related to which diseases, the chance that somebody with certain genes gets a particular disease is not much greater than the chance that somebody without these genes will. Scientists have discovered two genes, the brca genes, that seem to be highly correlated with whether or not a person will develop breast cancer. These genes are exceptions, however, because it is highly unlikely that we will find such a direct correlation for many other diseases, said Holtzman.
In the case of breast cancer, having a mutated brca gene does not mean that the person will get the disease for sure. There are other genetic and environmental factors involved. Its predictive value is even smaller because less than 4 percent of all breast cancer patients actually have the rare brca gene.
Even if scientists are able to determine that having a certain gene or genes increases the personÕs risk of getting a particular disease, Holtzman questioned whether people would want to know or care.
ÒPeople arenÕt terribly interested in knowing risks that are much below 50 percent,Ó said Holtzman. ÒEven if a person has a 25 percent greater chance [of getting a particular disease], they wouldnÕt take a drug for the rest of their life or change their lifestyleÓ as preventative measures.
This scenario is a subtle effect of genetic determinism because a person might say ÒItÕs in my genes, so thereÕs nothing I can do about it,Ó he said. Contrary to popular belief, a few treatments to correct or compensate for gene defects have already been developed, said Holtzman.
Despite all of its limitations, knowing the human genome will still teach us a lot, Holtzman said. Besides helping to predict, diagnose and treat simple diseases, it will also help us understand how some genes affect drug sensitivity and resistance. We have already discovered multidrug resistance genes that reduce sensitivity to leukemia treatment.
ÒGenetics has a lot to contribute to how our cells and organs work. We should recognize this without making claims that it will revoltionize medicine,Ó Holtzman said. ÒRecently weÕve spent more on the genetic research side and neglected other factors, but we need to think more globally.Ó
Social smoking intervention policies, for example, have had a greater effect on decreasing the occurrence of lung cancer than any genetic discoveries to date.
ÒOur overall positive goal is to improve peopleÕs health,Ó he said. ÒTo accomplish this we might succeed better by reducing inequities in health, improving the environment, and providing adequate health care to every one than we would by investing heavily in genetics.Ó
Holtzman is a professor of pediatrics, health policy and epidemiology at Johns Hopkins University. His article ÒWill Genetics Revolutionize Medicine?Ó was published in the New England Journal of Medicine last July.
News Writer
Our expectations for the potential of genetic research should not be too high, said Doctor Neil Holtzman, a professor at Johns Hopkins, in a lecture Friday at the North Central Indiana Ethics Consortium at Notre Dame.
ÒGenetics will advance knowledge, but its effect on health or reducing the burden of common complex diseases will not be terribly great,ÓHoltzman said.
Even after last weekÕs highly publized announcement that scientists have figured out the human genome sequence, they are still in the process of decifering it. Researchers estimate that there about 30,000 genes, but, in terms of function, only a couple thousand have been identified, according to Holtzman.
As this genetic research has progressed, Òrevolutionary claims have been made [by both the media and the scientific community] about the ultimate impact of genetics on clinical medicine,Ó he said
Authorities in the field promised that mapping the human genome would lead to new strategies to prevent common diseases.
Such promises eventually led to the optimism expressed in a story in The New York Times, ÒGenetic Code of Human Life is Cracked by Scientists.Ó The article said the achievement Òrepresents a pinnacle of human self-knowledge,Ó and that understanding them holds the key to the script of the human organism.
Holtzman said that these claims are unrealistic.
ÒThe new genetics will not revolutionize the way in which common diseases are identified or presented,Ó he said.
Scientists and doctors are likely to succeed in their attempt to predict, diagnose and treat simple diseases that are caused by mutations in one gene, according to Holtzman. Unfortunately, these simple diseases are much more rare than normal complex diseases, such as cancer. These diseases depend on environmental factors and complicated interactions between several genes.
ÒItÕs not impossible, but highly unlikely that weÕll be able to identify all of the genes involved in complex diseases,Ó Holtzman said. ÒIf we were able to do this, then maybe it would lead to genetics revolutionizing medicine. But this wonÕt happen, at least in our lifetime.Ó
Even if researchers were able to determine which genes were related to which diseases, the chance that somebody with certain genes gets a particular disease is not much greater than the chance that somebody without these genes will. Scientists have discovered two genes, the brca genes, that seem to be highly correlated with whether or not a person will develop breast cancer. These genes are exceptions, however, because it is highly unlikely that we will find such a direct correlation for many other diseases, said Holtzman.
In the case of breast cancer, having a mutated brca gene does not mean that the person will get the disease for sure. There are other genetic and environmental factors involved. Its predictive value is even smaller because less than 4 percent of all breast cancer patients actually have the rare brca gene.
Even if scientists are able to determine that having a certain gene or genes increases the personÕs risk of getting a particular disease, Holtzman questioned whether people would want to know or care.
ÒPeople arenÕt terribly interested in knowing risks that are much below 50 percent,Ó said Holtzman. ÒEven if a person has a 25 percent greater chance [of getting a particular disease], they wouldnÕt take a drug for the rest of their life or change their lifestyleÓ as preventative measures.
This scenario is a subtle effect of genetic determinism because a person might say ÒItÕs in my genes, so thereÕs nothing I can do about it,Ó he said. Contrary to popular belief, a few treatments to correct or compensate for gene defects have already been developed, said Holtzman.
Despite all of its limitations, knowing the human genome will still teach us a lot, Holtzman said. Besides helping to predict, diagnose and treat simple diseases, it will also help us understand how some genes affect drug sensitivity and resistance. We have already discovered multidrug resistance genes that reduce sensitivity to leukemia treatment.
ÒGenetics has a lot to contribute to how our cells and organs work. We should recognize this without making claims that it will revoltionize medicine,Ó Holtzman said. ÒRecently weÕve spent more on the genetic research side and neglected other factors, but we need to think more globally.Ó
Social smoking intervention policies, for example, have had a greater effect on decreasing the occurrence of lung cancer than any genetic discoveries to date.
ÒOur overall positive goal is to improve peopleÕs health,Ó he said. ÒTo accomplish this we might succeed better by reducing inequities in health, improving the environment, and providing adequate health care to every one than we would by investing heavily in genetics.Ó
Holtzman is a professor of pediatrics, health policy and epidemiology at Johns Hopkins University. His article ÒWill Genetics Revolutionize Medicine?Ó was published in the New England Journal of Medicine last July.
All News Stories for Monday, February 26, 2001
