Location of genetic varation is key to potential role in disease

Genetic variation is widely recognised as the key to survival and continued evolution of a species. A group of scientists led by Professor Chris Ponting at the MRC Functional Genomics Unit in Oxford have recently published a paper in the journal Genome Research that reveals that for humans at least, it’s where rather than if genetic variety exists that can determine healthy survival.

The team studied copy number variation (CNV); the variety in the number of copies of a gene that are present in an individual. CNV can vary widely in humans and is especially common near parts of the genome that have previously been duplicated. Copy number variants can be duplicated in some people and completely absent in others.

It has been suggested that CNVs are retained in the human genome because they offer some kind of beneficial potential to adapt. In contrast the study results show that CNVs exist not because positive selection is at play but because nature isn’t particularly efficient at throwing them out.

The study also identified stretches of DNA that can vary greatly between individuals without causing disease. The authors believe this may help to identify copy number variants that are linked to disease elsewhere in the genome.

Dr Caleb Webber, who contributed to the research project, explains the findings:

‘‘Variation in regions of the genome that appear to have no impact on susceptibility to disease is common. Identifying genes that frequently vary in copy number between individuals but that appear neither to be essential for human survival nor to be involved in disease, helps us to identify rarer differences in DNA in other parts of the human genome that are more likely to be linked to disease.’’