Genetics contributes to diabetes, HF, obesity risk in Native Hawaiian individuals
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In Native Hawaiian individuals, Polynesian ancestry is associated with elevated risk for diabetes, HF and obesity, according to a genetic study published in PLOS Genetics.
Charleston W.K. Chiang, PhD, assistant professor of preventive medicine at Keck School of Medicine of USC and of quantitative and computational biology at USC Dornsife College, and colleagues analyzed the health data and genetics of 3,940 people identifying as Native Hawaiian from the Multiethnic Cohort.
Possible genetic contributions
“The Multiethnic Cohort (MEC) was established by a collaboration between USC and the University of Hawaii in the 1990s to understand epidemiological risk factors that contribute to differences in disease risks between multiple ethnic minorities, such as Latinos and African Americans,” Chiang told Healio. “Native Hawaiians are one of the five main cohorts within the MEC. Genetic data became available in the mid-2000s and has been one of the risk factors that investigators examine to explain differences in disease risk. However, throughout these efforts, particularly from the genetic standpoint, the Native Hawaiians have been largely overlooked and ignored because they comprise a small proportion of the entire cohort. We wish to understand the possible genetic contributions (if any) to differences in disease risk in the Native Hawaiians, and this study is one of the first steps to that process.”
For each participant, the researchers estimated the genetic proportion of Native Hawaiian ancestry (global ancestry), presumed to be Polynesian, and estimated the ancestral component along each chromosome (local ancestry). The researchers then investigated the association of global and local ancestry with cardiometabolic traits, and adjusted for nongenetic components learned via questionnaires.
After adjustment, for every 10% increase in global Polynesian ancestry, there was an 8.6% rise in the odds of diabetes (P = 1.65 x 10-4), an 11% rise in the odds of HF (P = 2.8 x 10-4) and a 0.059 standard deviation increase in BMI (P = 1.04 x 10-10), according to the researchers.
Consistent with previous findings
“We found that proportion of Polynesian ancestry, which captures both genetic factors specific to Polynesian populations as well as nongenetic factors associated with the Polynesian culture or environment, is correlated with risk of BMI/obesity, type 2 diabetes and heart failure in Native Hawaiians. These are consistent with previous epidemiological findings that Native Hawaiians experience higher risk in these diseases when compared to European Americans or Asian Americans,” Chiang told Healio. “For some of the traits or diseases we examined (eg, BMI, type 2 diabetes and heart failure), our results suggest that there are variations in risk within the population of Native Hawaiians that can be partly explained by the proportion of Polynesian ancestry. The underlying contributors to this apparent association between ancestry and risk are likely both genetic and environmental factors that correlate with Polynesian ancestry. Our study implies that risk assessment in the clinic could take this into account when devising a treatment or prevention plan, and modifiable risk factors can be managed via intervention to improve the care of this population.”
Chiang said in an interview that individual estimates of proportion of ancestry are prone to estimation errors and other biases, so estimated proportion of ancestry should not be a criterion for membership in a population.
“It is also worth making it abundantly clear that while we focused on the genetic risk factors for complex traits and disease in the Native Hawaiians, genetics is only a contributing factor, maybe even a relatively small one, of the overall risk profile of a population,” he said. “Many other environmental, social and cultural factors also contribute to differences in risk between populations.”
For more information:
Charleston W.K. Chiang, PhD, can be reached at charleston.chiang@med.usc.edu.
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