Given the estimated 20,000 genes that determine the characteristics of human beings (and make up the human genome), identifying those that may be responsible for the development of ME/CFS is a challenge.
But the task can be simplified by first considering the symptoms of the disease, and then targeting the search to those genes known to be involved in the underlying processes (for example, the nerve dysfunction that causes difficulties in standing).
This type of research often looks for small genetic changes, known as single nucleotide polymorphisms (SNPs), which vary between individuals. Most SNPs have no effect, but some can alter an individual’s susceptibility to disease.
An Australian study published recently in the journal, BMC Medical Genetics, has taken this approach to look at a range of potentially relevant SNPs in ME/CFS, assessing how frequently they occurred in a group of 95 patients with the illness, and in 77 healthy people.
The investigators focused on SNPs affecting three types of structure involved in transport and communication between tissues and cells in the body; namely, transient receptor potential ion channels, acetylcholine receptors and adrenergic receptors.
Their main finding was that one specific SNP, affecting the gene ADRA1A, occurred in almost half of the ME/CFS patients, but in only a quarter of the healthy people.
ADRA1A is responsible for the manufacture of a specific type of adrenergic receptor which controls the contraction of smooth muscle cells. This control is essential in a range of biological processes involving the blood vessels, gastrointestinal system, kidneys and other organs.
It may be that ADRA1A is involved in the development of ME/CFS (at least in a subgroup of patients), and that further investigation into the function of the related adrenergic receptors in the disease may help explain the cause of some of the symptoms experienced by patients.
Genetic studies of this kind represent a potentially fruitful area of ME/CFS research and, thanks to your continued support, ME Research UK has itself funded projects analysing the relevance to the illness of SNPs, microRNA molecules and DNA sequencing.
However, we are a long way from being able to apply these findings to the diagnosis and management of ME/CFS. For a start, the results of individual studies such as this need to be replicated by other research groups and in other groups of patients.