NEW YORK (GenomeWeb News) – In a paper appearing online today in Science, members of the Human Genome Organization's Pan-Asian SNP Consortium reported on genetic patterns in more than 70 Asian populations.
The team, which included researchers from 10 Asian countries as well as investigators from the US, used microarrays to map the genetics of 73 Asian populations. They found that most genetic clusters corresponded to language groups, though geography was also a factor in these patterns. In addition, the study suggests an influx of individuals from Southeast Asia contributed genetically to many populations found in East Asia today.
"[O]n the basis of variation at a large number of independent SNPs, we observed that there is substantial genetic proximity of [Southeast Asian] and [East Asian] populations," the researchers wrote.
Members of the HUGO Pan-Asian SNP Consortium used the Affymetrix GeneChip Human Mapping 50K Xba Array to genotype 1,928 individuals from 73 Asian populations at 54,794 autosomal SNPs. They also assessed samples from two non-Asian HapMap populations.
Their ancestry analyses suggest Asian populations harbor genetic contributions from five language groups, three ethnic groups, and two small groups representing specific populations in Borneo and Thailand.
Most of the genetic patterns corresponded with language groups, the researchers reported. But there were exceptions. For instance, they found eight populations in which genetic and language patterns did not match. Rather, individuals in these populations tended to cluster more closely with nearby geographic populations.
"These patterns are consistent either with substantial recent admixture among the populations, a long history of language replacement, or uncertainties in the linguistic classifications themselves," the researchers explained.
In general, haplotype diversity was highest in southern Asia and dwindled in samples taken further north.
Most East Asian haplotypes — some 90 percent — turned up in Southeast or Central-South Asia. But more of these haplotypes were unique to Southeast Asia: about half of East Asian haplotypes were present only in Southeast Asia, the researchers reported, compared with the five percent of East Asian haplotypes that were found in Central-South Asia alone.
Such patterns indicate that migration from Southeast Asia into East and North Asia, the team explained. They proposed a model whereby ancestors of modern day Asian populations settled in India before migrating to Thailand, Malaysia, Indonesia, and the Philippines. From there, it appears one or more groups traveled north, mixing with other populations already living in these regions.
Along with these insights into historical human migrations, those involved say such studies are necessary for designing and interpreting future genetic and pharmacogenomic studies in Asia.
In a statement released today, HUGO President Edison Liu, executive director of the Genome Institute of Singapore, said he and his team are expanding on the current study and plan to do additional genetic analyses in Central Asia and the Polynesian islands.
"We also aim to be more detailed in our genomic analysis and plan to include structural variations, as well as over a million single nucleotide polymorphisms in the next analysis," Liu added.