Lifestyle and socioeconomic factors are often associated with a higher prevalence of obesity, type 2 diabetes and cardiovascular disease in native Hawaiians, but new research has found that Polynesian genetic ancestry also increases the risk of certain chronic diseases.
Using genetic data from nearly 4,000 individuals 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 country’s Polynesian genetic ancestry person, the chances of being diabetic and suffering from heart failure increased by 8.6% and 11%, respectively.
A greater amount of Polynesian genetic ancestry has also been associated with a higher body mass index, a measure of body fat, according to the study published today in PLOS Genetics.
But genetics is not the only, or even the main, determinant of obesity and chronic diseases in any ethnic group, the study emphasized, saying that “lifestyle, socioeconomic factors and other environmental factors can play as big or a bigger role. . However, we hope that genetic studies will be a window for understanding the biology behind these diseases, in a way that is targeted and eventually beneficial to the health of the needy population. “
Epidemiological studies have shown that 49% of native Hawaiian adults are obese, compared with 21% of European Americans and 13% of Japanese Americans living in Hawaii, according to the new report, whose co-authors include Lynne Wilkens and Loic Le Marchand from the University of Hawaii Cancer Center. Native Hawaiians are also two to three times more likely to develop type 2 diabetes and 1.7 times more likely to develop cardiovascular disease than American Europeans.
Thus, Chiang said the team’s findings did not surprise him as much as the scarcity of genomic resources to study native Hawaiians, which he described as “almost nonexistent”.
“I know from previous epidemiological studies that native Hawaiians are known to have a high risk of various diseases or cardio-metabolic traits when compared to European or Asian Americans, but from a genetic point of view, I think they are little studied, so we were there to fill the gap. “
Filling in the gaps to understand the genetic underpinnings of disease risk in ethnic populations is of particular interest to Chiang and his team at the USC Center for Genetic Epidemiology.
“The genetic field has always focused a lot on European populations because there is a long history for that and, obviously, many of the genetic studies were conducted by European or Western researchers who had a long history of these well-maintained cohorts of European populations. So, in a way, it made sense that many of these genetic studies were done in Europeans, ”he said.
To expand the research, the USC and the UH Cancer Center established the Multiethnic Cohort Study in the mid-1990s, enrolling 104,000 residents of Hawaii and 112,000 residents of Los Angeles, representing five ethnic groups, including native Hawaiians. Participants answered a comprehensive questionnaire on diet, medications, physical activity, family medical history and other personal information, with updates every five years to monitor the development of cancer and chronic illnesses.
From that larger group, Chiang’s team arrived at their findings by examining the genetic data of the entire genome of about 3,940 self-identified native Hawaiians, locating components inherited from Polynesian ancestors and connecting them to the health conditions reported by study participants .
“For me, this is the first step towards more personalized medicine, knowing that these are a person’s particular attributes for assessing disease or risk,” said Chiang.
Although an individual’s ancestry does not determine their fate in terms of health outcomes, the study said that additional research “may be able to identify genetic variants and underlying biological factors specific to Polynesian populations, which would allow a lifestyle to be chosen. or pharmaceutical interventions to reduce the increased risk of these diseases. ”