Research has found a group of genes that could slow down the development of diseases like multiple sclerosis and cancer.
Scientists at the University of Edinburgh were able to identify genetic "brakes", which explain why people develop diseases in different ways.
It is hoped the discovery, which is published in the Nature Genetics journal, can be used to create new treatments to target weak spots in the gene structure and slow down or stop such illnesses.
It was previously thought that a group of "master" genes was responsible for controlling the growth of cells, but this new study has found that there are actually hundreds of genes that interact with each other.
It is the variations in the network which is thought to be responsible for the growth of diseases.
Professor David Hume, of the University of Edinburgh's Roslin Institute, who led the study, said: "This study has effectively shown us where the brakes are which could slow down or stop diseases like cancer and multiple sclerosis.
"We believe this could lead to treatments and cures for many diseases of the immune system."