IT鈥橲 the blueprint for life, but not all of our genome is truly mission-critical. Now the first systematic search for non-essential regions of the human genome is providing an estimate of the 鈥渕inimal genome鈥� needed by a healthy human being, as well as clues to our evolutionary history.
Previous studies suggested it is possible to lead a full and healthy life without every single bit of the genome. 鈥淵ou don鈥檛 need a complete genome to be a complete person,鈥� says Terry Vrijenhoek of the Radboud University Nijmegen Medical Centre in the Netherlands.
To put a figure on how much of our DNA is non-essential, Vrijenhoek and his colleagues screened the genomes of 600 healthy students, searching for chunks of DNA at least 10,000 base pairs in length that were missing in some individuals. Across all the genomes, about 2000 such chunks were missing 鈥� amounting to about 0.12 per cent of the total genome.
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Just over two-thirds of the 鈥渄eletions鈥� were found in more than one individual, and a third in more than 5 per cent of people in the study. The deletions disrupted 39 known genes, most of which are involved in immune defence, smell and other senses. Vrijenhoek will on 24 October at the annual meeting of the American Society of Human Genetics in Honolulu, Hawaii.
Why do we have non-essential DNA? Team leader suggests that the regions his team flagged up may once have been essential but aren鈥檛 any more, either because we now need different abilities to survive, or genes have evolved elsewhere in the genome to do the same job, perhaps better.
Earlier this year researchers at the Sanger Institute in Cambridge, UK, used a scan of disrupted genes to estimate that around . Veltman says his team is the first to search the whole human genome 鈥� not just genes 鈥� for non-essential elements.
鈥淎bout 2000 chunks of DNA, some of which disrupted genes, were found to be non-essential鈥�
He notes that which genes are non-essential may vary between ethnic groups.