A 30-year study has found European and Polynesian gene pools are different and should be treated separately when matching tissues for transplants or prescribing medicines.
The research, led by Victoria University molecular geneticist Dr Geoff Chambers and published in the New Zealand Science Review, found that differences between Maori and Pasifika gene pools and those of European ancestry could have big medical consequences.
It follows earlier findings by Chambers that led him to argue against a "one size fits all" approach to healthcare.
His work has also created molecular methods to pinpoint indicators for a range of diseases, including diabetes.
Chambers said the studies into tissue typing and blood group analysis showed Maori and Pasifika were more likely to find donors from someone within their own ancestral background.
"This also concerns people of first generation mixed ethnicity - those who have one European genome and one Maori or Pasifika genome."
The only people who were likely to be good prospects for tissue donors for them were people who shared a similar genetic make-up, he said.
"The more blended our ethnicities become, the better the chance of finding a match in New Zealand but the poorer the chance of finding an overseas donor.
"The latter has a much larger register of donors."
Chambers believed the research, co-authored by Dr Hisham Edinur from the University of Science, Malaysia, and Dr Paul Dunn from University Hospitals of Leicester in the UK, had implications for the public health system and transplant success.
"Our data help to explain why some diseases are more common in one group than another, and show how immune systems from groups may respond to diseases in different ways - ways we don't even know yet," he said.
"These results open the door to many future studies - if we want to use new medicines effectively, then we have to do it differently and based on our new knowledge about genetic ancestry."
Over the past 25 years, Chambers has identified genetic markers that trace the origin of Austronesian people - Polynesian, Maori, Melanesian, Micronesian and people from parts of Southeast Asia - tens of thousands of years back to Taiwan.
"Because of their genetic commonality, medical genetic studies done in Southeast Asian populations are likely to be of interest and concern to Maori or Pasifika, and likewise.
"They're part of a very big whanau - and it is an area where we could be looking for further insights into health and medications."
Previously, Chambers has said an era where we'll all receive personalised medicine based on our own distinct DNA make-up could be just a decade away.