Scientists have for the first time sequenced the complete diploid genomes of an Asian and an African. It is hoped that the research, published in the journal Nature, will help to shed light on how people from different ethnic backgrounds respond to medicine and help to explain the unusually high or low incidences of certain diseases seen among some populations.
The two anonymous individuals, one of Nigerian and the other of Han Chinese descent, are the first non-Europeans to have had their genomes sequenced. Jim Watson, who discovered the structure of DNA with colleague Francis Crick in 1953, and Craig Venter, one of the scientists to sequence the Human Genome, - both Europeans - are the only other two individuals to have published their complete genome sequences.
The African genome sequence is the work of an international consortium, including researchers at the Wellcome Trust Sanger Institute near Cambridge. The Asian genome was the work of the Beijing Genomics Institute in China, who announced the completed sequence in 2007, but have only now published it.
When the first human genome sequence was completed in 2003, it took years and cost millions of pounds. However, for these studies the researchers used next generation sequencing machines by the company Illumina Inc., based in California, to sequence the two 3 billion base-pair DNA sequences in just months and at a fraction of the cost.
While sequencing entire genomes is now relatively straightforward, making sense of the information they contain remains a significant challenge. The main goal of genome sequencing projects is to identify SNPs (single nucleotide polymorphisms) - single 'letter' changes in the DNA sequence - which might be associated with disease susceptibility or drug response.
The African genome team reported around 4 million SNPs and the Asian genome team 3 million, with many of these common to those identified previously in Watson and Venter's genomes. However, further studies will be necessary to determine the effect of most of genetic variants on a person's health - if any.
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