Lifestyle and socio-economic factors are often linked to the higher prevalence of obesity, type 2 diabetes, and cardiovascular disease among native Hawaiians. However, new research has found that Polynesian genetic ancestry also increases the risk of certain chronic diseases.
Using genetic data from nearly 4,000 people involved in a long-term multiethnic health study, a team of researchers led by Charleston Chiang of the Center for Genetic Epidemiology at the University of Southern California found that for every 10% increase in a person’s Polynesian genetic ancestry, the The likelihood of suffering from diabetes and heart failure increased by 8.6% and 11%, respectively.
A greater amount of Polynesian genetic ancestry was also linked to a higher body mass index, a measure of body fat, according to the study published today in PLOS Genetics.
Genetics, however, is not the only, or even the most important, determinant of obesity and chronic disease in an ethnic group, the study stressed, saying, “Lifestyle, socio-economic and other environmental factors could play an equally large or greater role. However, we hope that the genetic studies will provide a window to understanding the biology behind these diseases, in a way that is targeted and ultimately beneficial to the health of the underserved population. “
Epidemiological studies have shown that 49% of adult Native Hawaiians are obese, compared with 21% of European Americans living in Hawaii and 13% of Japanese Americans. This emerges from the new report, co-authored by Lynne Wilkens and Loic Le Marchand from the Cancer Center of the University of Hawaii. Native Hawaiians are two to three times more likely to develop type 2 diabetes and 1.7 times more likely to develop cardiovascular disease than Europeans.
Chiang said the team’s results didn’t surprise him as much as the lack of genomic resources to study native Hawaiians, which he described as “almost non-existent.”
“I know from previous epidemiological studies that native Hawaiians are at increased risk for various cardio-metabolic diseases or traits when compared to European or Asian Americans, but genetically I think they are very little researched, so were we there to fill the void. “
A particular interest for Chiang and his team at the USC Center for Genetic Epidemiology is to fill the gaps in understanding the genetic basis of disease risk in ethnic populations.
“The genetic field has always focused heavily on European populations because there is a long history for it and obviously a lot of genetic studies have been done by European or Western researchers who have had a long history of this well-kept cohort of European populations. So, in a way, it made sense that a lot of these genetic studies were done on Europeans, ”he said.
To expand the research, USC and the UH Cancer Center launched the Multiethnic Cohort Study in the mid-1990s, which included 104,000 Hawaiian and 112,000 Los Angeles residents representing five ethnic groups, including native Hawaiians. Participants completed a comprehensive diet, medication, physical activity, family history, and other personal information questionnaire every five years to track cancer and chronic disease development.
From this larger group, Chiang’s team arrived at their conclusions by examining the genome-wide genetic data of approximately 3,940 self-identified Native Hawaiians, locating the components inherited from Polynesian ancestors, and relating them to the health conditions reported by study participants.
“For me, this is the first step towards more personalized medicine, knowing that these are the unique characteristics of a person for assessing disease or risk,” said Chiang.
While an individual’s ancestry does not determine their fate in terms of health outcomes, the study states that further research “may identify genetic variants and underlying biological factors that are specific to Polynesian populations and lifestyle or pharmaceutical choices Interventions would enable them to reduce their higher risk for these diseases. “