Multiple sclerosis (MS) is a variable disease that involves the immune system. It may be mild in some patients that experience tingling sensations or numbness, but in others, it can be debilitating and may cause blindness or paralysis. The disorder impacts the central nervous system, including the optic nerve in the brain. More than 2.3 people around the world are affected by the disease, and most are between 20 and 50 years old. Scientists haven’t yet figured out what triggers MS, though it’s thought to be caused by a combination of genetic and environmental factors.
Researchers have used genome-wide association studies (GWAS) to learn more about the genetic factors underlying the disorder. These studies can assess genetic variations in individuals to identify small changes in genes that are linked to disease. By 2018, over 230 genetic risk factors for MS had been identified using GWAS technologies. However, scientists have had difficulty interpreting the results of that work, and many had not been studied in detail.
Scientists have now combined GWAS with a non-invasive imaging tool called OCT (optical coherence tomography), which is used to diagnose problems with nerves in the eye. It’s thought that the progression of MS can be better understood in patients using this technique.
GWAS was applied to individuals with MS that had been tested with OCT and other tools over an average of three years. The investigators were looking for variations in genes that were linked to the loss of nerves or degenerating vision. The work was reported in Brain.
The research team found that severe forms of MS, which impact vision, are associated with several genetic variations. These variants are present in a group of immune system proteins that are involved in the complement cascade, which is how the human body responds to foreign pathogens like bacteria. These proteins have also been shown to play a role in nervous system damage and the progression of MS. Some are strongly linked to the nerve problems that OCT identifies.
More work will be needed to confirm these findings, but we now know more about the genetic factors that underlie the severity of MS, especially the vision disorders that are seen in the disease. This work may help identify new treatment approaches.