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University of Cincinnati Academic Health Center
Publish Date: 07/18/00
Media Contact: AHC Public Relations, (513) 558-4553
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DNA Tracks Ancient Polynesian Origins

Cincinnati--Published today in the Proceedings of the National Academy of Sciences, a genetic study of 'Polynesian origins: Insights from the Y chromosome" gives scientific evidence that traces the migration of prehistoric ancestors from the heart of the agricultural mainland of Southeast Asian to the thousands of Polynesian islands that stretch 6,000 miles off the southeast coast. Conducted by researchers from China, the US, England, and Australia, this research disputes earlier theories that traced ancestral roots of Polynesian people to Taiwan. Ranjan Deka, PhD, associate professor, University of Cincinnati (UC) Department of Environmental Health, is the leading investigator of this study. Other major investigators are: Li Jin, PhD, and Bing Su, PhD, from the University of Texas Health Science Center at Houston.

"Understanding the prehistoric migration and genetic structure of human populations helps scientists to find disease-causing genes, the next step of which is to develop therapies to treat genetic disorders at the molecular level," says Deka, who studies genetic variation at the UC Medical Center. Creating a genetic profile of people who live in remote areas such as the Polynesian Islands helps scientists to identify what specific genes predispose their population to certain diseases such as diabetes, while using DNA to trace their relationship to ancestors.

The researchers of this study based their conclusions on DNA analysis from the human Y chromosome. The Y chromosome determines the persons of the male sex and is transmitted by fathers to their sons as a single copy. All other chromosomes contain two copies, with one inherited from the mother and the other from the father. Mitochondrial DNA (mtDNA--from outside the nucleus) are passed on only through the mother and have a higher rate of mutation than DNA from the Y chromosome. Although both Y chromosome and mtDNA research can be used to create genetic profiles of specific populations, mtDNA have a higher rate of mutation than DNA from the Y chromosome. "The new research refutes earlier theories that were based on mtDNA research which linked present day Polynesians with historic populations found in Taiwan," says Deka.

During the recombination phase of gamete formation, when genes from each parent are randomly exchanged to create the egg or sperm, only the Y chromosome keeps its inherited legacy intact. Deka and his collaborators used a new type of DNA marker that remains stable over generations and can provide a true chronicle or lineage of past evolutionary genetic histories of specific populations. For more information about this study or Deka's current research to find genes of adult onset diabetes among the Samoans of Polynesia, contact ranjan.deka@uc.edu via email, or by calling him at (513) 558-5989.



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