Scientists’ Genetic Mapping of Han Chinese Provides Invaluable Information of Ethnic Chinese Ancestry
News Dec 07, 2009
Scientists have, for the first time, successfully created a fine ‘genetic map’ of the Han Chinese, the largest ethnic population in the world, through a genome-wide DNA variation study.
This ‘genetic map’ provides invaluable information on the population structure and evolutionary history of this group of people, and with that, helps to determine the design and interpretation of genetic studies of human diseases among them.
The study, led by Dr Liu Jianjun, Human Genetics Group Leader at the Genome Institute of Singapore (GIS), was published online on 25 November 2009 in the American Journal of Human Genetics. The GIS is a biomedical research institute of the Agency for Science, Technology and Research (A*STAR), Singapore.
Using genome-wide DNA variation information in over 6,000 Han Chinese samples from 10 provinces in China, the scientists were able to show that the northern inhabitants were genetically distinguishable from those in the south, which seems to be extremely consistent with the historical migration pattern of the Han Chinese. It also revealed that the genetic divergence was closely correlated with the geographic map of China. The close resemblance between the ‘genetic’ and geographic maps of the Han Chinese suggests the persistence of local co-ancestry in the country.
Dr Liu said, “The genome-wide genetic variation study is a powerful tool which may be used to infer a person’s ancestral origin and to study population relationships. For example, an ethnic Chinese born and bred in Singapore can still be traced back to his or her ancestral roots in China. By investigating the genome-wide DNA variation, we can determine whether an anonymous person is a Chinese, what the ancestral origin of this person in China may be, and sometimes which dialect group of the Han Chinese this person may belong to. More importantly, our study provides information for a better design of genetic studies in the search for genes that confer susceptibility to various diseases.”
Of particular interest to Singapore are the findings that while the majority of Singaporean Chinese hail from Southern China as expected, some have a more northern ancestral origin.
GIS Executive Director, Prof Edison Liu, said, “Genome association studies have provided significant insights into the genes involved in common disorders such as diabetes, high cholesterol, allergies, and neurological disorders, but most of this work has been done on Caucasian populations. More recently, Dr Liu Jianjun from our institute has been working with his Chinese colleagues to define the genetic causes of some of these diseases in Asian populations. This work refined those tools so that the results will not be obscured by subtle differences in the genetic diversity of Asian populations. In the process, Dr Liu has reconstructed a genetic historical map of the Chinese people as they migrated from south to north over evolutionary time.“
Prof Chia Kee Seng, Head, Department of Epidemiology & Public Health, NUS Director, NUS-GIS Centre for Molecular Epidemiology, also added, “There are definite differences in genetic architecture between populations. We have seen this in the Singapore Genome Variation Project, a Joint NUH-GIS effort. Understanding these differences is crucial in exploring how genes and environment interact to cause diseases.”
The finding is part of a larger ongoing project on the genome-wide association study of diseases among the Chinese population. The project is a collaboration between GIS and several institutions and universities in China.