There is a link between Polynesian Hawaiian ancestry and increased risk of Type 2 diabetes, heart failure and obesity, according to a first-of-its-kind genetic study published on Thursday.
The new study, published in PLos Genetics, aimed to rectify a gap in genetic research by becoming the first to systematically investigate the genomes of Native Hawaiians and test components for genetic ancestry-associated health risks. Among the findings was a chromosomal region tied to Type 2 diabetes, although the researchers could not determine if the association is causal.
Native Hawaiians have been known to be at higher risk for cardiometabolic diseases compared to European or Asian Americans living in Hawaii, thanks to epidemiological studies.
“But what has been lacking quite a bit is any kind of genetic study in Native Hawaiians,” Charleston Chiang, the study's lead researcher and an assistant professor of preventive medicine at the University of Southern California's Keck School of Medicine, told The Academic Times.
The study is partly a product of the Multiethnic Cohort Study, a joint project of USC and the University of Hawaii and the only public resource with available genetic data for Native Hawaiians. Chiang’s research team drew from questionnaires, lab measurements and Medicare claims. Then the researchers correlated health data and the genetics of 3,940 Native Hawaiians from the Multiethnic Cohort Study.
“We leveraged the genetic data to define Polynesian ancestry, and then we could show that a higher proportion of Polynesian ancestry is associated with a risk of obesity, Type 2 diabetes and heart failure in our study,” Chiang said.
Specifically, the first part of the study established that there is a link between Polynesian ancestry and metabolic diseases that researchers tested for. However, the link could be due to genetic risk factors, environmental factors, cultural practices and the like.
So for the second phase of the study, researchers used a genome mapping technique to also identify local genomic regions that could potentially be contributing to these diseases in the study group.
That's how they identified a region on chromosome 6 associated with Type 2 diabetes.
“The problem is that the standard in human genetic studies is replication, and there is simply no other Polynesian populations that we can reach out to and try to replicate this finding,” Chiang said. “So, the jury is still out. We did find this one region but we are not sure whether it is a true causal association, or just a chance finding, because we have not been able to find a second cohort to replicate it.”
The lack of available genomic resources is a problem that must be addressed, Chiang said. Policymakers should invest more into understudied minorities that also tend to be smaller groups than others in the U.S., he suggested, such as African Americans or Hispanics. He also sees a need for community outreach and engagement to establish research paradigms.
“There is this general distrust between the community and the scientists and the policymakers,” Chiang said.
His immediate next step is to build up unavailable genomic resources using the data USC has and start adding to a repertoire of research tools that could be used to examine understudied minority populations.
“The next thing I want to do is to engage more with the community and build long-term relationships that will allow the training of future scientists from the community, and expansion in the recruitment of more individuals willing to participate in research ... to have the necessary statistical power to make genetic findings,” he said.
The study, “The impact of global and local Polynesian genetic ancestry on complex traits in Native Hawaiians,” was published in PLos Genetics on Feb. 11. The authors of the study were Hanxiao Sun, Meng Lin, Tsz Fung Chan and Bryan L. Dinh, University of Southern California; Emily M. Russell and Ryan L. Minster, University of Pittsburg; Take Naseri, Ministry of Health, Government of Samoa; Muagututi‘a Sefuiva Reupena, Lutia i Puava ae Mapu i Fagalele; and Annette Lum-Jones, University of Hawaii.