It is common knowledge that with many illnesses, such as cancer, risk of development is partly determined by family history of the disease. But new research suggests that "random chance" decides if a certain gene copy that is inherited from our mother or father is actually used.
Researchers from the Karolinska Institutet in Sweden and the Ludwig Institute for Cancer Research in the UK say that their findings, published in the journal Science, may explain why some people become ill even if they have the same gene copy as healthy relatives.
The investigators explain that there are two copies of each gene in the human body - one which is inherited from our mother and one from our father.
They note that the majority of existing research suggests that both gene copies are used equally, but their new study suggests otherwise.
To reach their findings, the researchers created a technique which allowed them to closely analyze how genes work in individual cells - something lead author Dr. Rickard Sandberg says has not been done before.
the methods for studying gene activity have been based on analyzing hundreds to thousands of cells at a time. This gives you an average, where the contribution of the copies from the father and mother of the same gene, known as the alleles, are mixed together," he explains.
"We have instead developed a method that allows us to analyze the gene activity in individual cells, which enabled this discovery."
Gene copy 'randomly activated' in each cell
Their new technique led them to discover that in each individual cell, one gene copy is "randomly chosen" for activation. Furthermore, which gene is activated can also change over time.
The investigators say their findings could open new doors for biomedical research. For example, they note that their discovery could help explain why identical twins - who have almost exactly the same genes - can have different characteristics.
With regards to illness, the researchers note that many diseases only arise in a subset of patients, or vary in terms of severity, which makes them difficult to explain and treat. They say that the process of random gene copy activation may help shed light on certain disease activity.
Dr. Sandberg adds:
"This discovery is also interesting for basic research regarding gene activity and regulation. For example, it highlights the fact that studies and models of gene activity should be made using resolution for both the maternal and paternal alleles."