WHERE PEOPLE LIVE, HOW they grow up and who they are genetically all have a hand in shaping health outcomes – though genetics may have an edge as a health influencer, according to a massive new study of twins in the U.S.
The findings, published this week in Nature Genetics, indicate that the nature-versus-nurture debate yields no simple answer: While both genetic and environmental factors can play a significant role in determining whether someone has a disease, how much weight each holds depends on the type of health condition.
Cancer Rates Decline, but Wealth a Factor
"This relationship between genetics and ZIP code is an incredibly complex one, and it's nuanced," says senior author Chirag Patel, an assistant professor of biomedical informatics in the Blavatnik Institute at Harvard Medical School. "Patterns emerged that seem to indicate tension between environment and genetics in different disease categories."
Researchers analyzed health claims data for more than 56,000 pairs of twins in the U.S. who were up to 24 years old, and examined the prevalence of a broad range of 560 health conditions.
Using health data such as blood test results and cholesterol levels, along with air pollution levels and socioeconomic status derived from patient ZIP codes, they estimated that about 40 percent of diseases studied were influenced by a genetic component, while 25 percent were at least partially driven by twins' "shared environment" – factors such as living in the same household and neighborhood.
Genetic factors came into play for cognitive disorders – such as attention deficit hyperactivity disorder – the most, while connective tissue diseases were the least influenced by them. Shared environmental factors were strongest for eye disorders and respiratory diseases, and weakest for reproductive conditions, according to the study.
[ READ: Health Equity Not Just About Race – It’s Also About Place ]
On average, genetics accounted for about 31 percent of variation among diseases, with shared environment accounting for about 9 percent. Remaining drivers could encompass incomplete data or some combination of randomness and other "specific environmental risks," which include "the different experiences those twins might have in their daily lives," such as eating different diets, Patel says.
"The remainder of the variation in all of these diseases could not be explained by ZIP code or the shared environment, nor genetics," he says. "What is it about this specific environment that drives variation with all these diseases? That's an outstanding question for us in the field, is how to better pin that variation down."
Holocaust Survivors Sicker, Yet Live Longer
Researchers did note strong links between environmental factors and some health conditions. Socioeconomic status was a significant driver of morbid obesity, for example, while average temperature affected the burden of lead poisoning.
Patel says these findings offer insight on "what diseases have a large share in the environment or ZIP code component, so we can better provide health care to those at risk for those diseases."
Other questions remain about the role of socioeconomic status and other environmental factors in determining health. In this study, all patients were privately insured and had at least three years of data available, so people covered by Medicaid or those who were uninsured – often those in the lowest income brackets – were excluded from the research.
"Our population was biased – we did have an insured population," Patel says. "Hopefully in future studies, we'll be able to query a population that is often underlooked and understudied in research like this."
The findings, published this week in Nature Genetics, indicate that the nature-versus-nurture debate yields no simple answer: While both genetic and environmental factors can play a significant role in determining whether someone has a disease, how much weight each holds depends on the type of health condition.
"This relationship between genetics and ZIP code is an incredibly complex one, and it's nuanced," says senior author Chirag Patel, an assistant professor of biomedical informatics in the Blavatnik Institute at Harvard Medical School. "Patterns emerged that seem to indicate tension between environment and genetics in different disease categories."
Researchers analyzed health claims data for more than 56,000 pairs of twins in the U.S. who were up to 24 years old, and examined the prevalence of a broad range of 560 health conditions.
Using health data such as blood test results and cholesterol levels, along with air pollution levels and socioeconomic status derived from patient ZIP codes, they estimated that about 40 percent of diseases studied were influenced by a genetic component, while 25 percent were at least partially driven by twins' "shared environment" – factors such as living in the same household and neighborhood.
Genetic factors came into play for cognitive disorders – such as attention deficit hyperactivity disorder – the most, while connective tissue diseases were the least influenced by them. Shared environmental factors were strongest for eye disorders and respiratory diseases, and weakest for reproductive conditions, according to the study.
[ READ: Health Equity Not Just About Race – It’s Also About Place ]
On average, genetics accounted for about 31 percent of variation among diseases, with shared environment accounting for about 9 percent. Remaining drivers could encompass incomplete data or some combination of randomness and other "specific environmental risks," which include "the different experiences those twins might have in their daily lives," such as eating different diets, Patel says.
"The remainder of the variation in all of these diseases could not be explained by ZIP code or the shared environment, nor genetics," he says. "What is it about this specific environment that drives variation with all these diseases? That's an outstanding question for us in the field, is how to better pin that variation down."
Holocaust Survivors Sicker, Yet Live Longer
Researchers did note strong links between environmental factors and some health conditions. Socioeconomic status was a significant driver of morbid obesity, for example, while average temperature affected the burden of lead poisoning.
Patel says these findings offer insight on "what diseases have a large share in the environment or ZIP code component, so we can better provide health care to those at risk for those diseases."
Other questions remain about the role of socioeconomic status and other environmental factors in determining health. In this study, all patients were privately insured and had at least three years of data available, so people covered by Medicaid or those who were uninsured – often those in the lowest income brackets – were excluded from the research.
"Our population was biased – we did have an insured population," Patel says. "Hopefully in future studies, we'll be able to query a population that is often underlooked and understudied in research like this."
No comments:
Post a Comment