MS susceptibility gene affects immune function

Epub ahead of printKofler et al. The CD6 Multiple Sclerosis Susceptibility Allele Is Associated with Alterations in CD4+ T Cell Proliferation. J Immunol. 2011 Aug 17.

"Up until now I have tried to avoid giving you too much immunology on this site. Now for something completely different."

Genetic studies have revealed a large number of genetic associations with MS. Despite this progress, the mechanisms underlying the contribution of the genetic variants to the onset of MS remain mostly unknown. A recent analysis of all the genome-wide association studies of MS identified a new susceptibility locus that is found close to a gene called CD6. 

CD6 plays an important role in the maintenance of T cell activation and proliferation. 

T cells are thought to be the main immune cell that orchestrates the damage in MS. 

In this study the researchers examined the biologic effects of the risk-associated genetic variant in CD6.

They report that the MS susceptibility variant in CD6 is associated with decreased expression of the full-length version of CD6 in the two major types of T-cells called CD4(+) and CD8(+) T cells. 

As a consequence of this, proliferation of T cells is diminished during long-term activation of CD4(+) T cells from subjects with the risk allele. 

These findings indicate that the MS risk variant in the CD6 gene is associated with altered proliferation of T cells and demonstrates the possible influence of a disease-related variants on immune function.

"Wow, what a mouthful!"

"In short, one of the many genetic variants that increase one's risk of getting MS has functional effects on the immune system. If you happen to be a carrier of this genetic variant a subtype of your T cells is unable to proliferate (divide and increase in numbers) when activated." 

"I wonder how this affects your risk? You would expect that anything that increases your risk would result in an increase in proliferation of autoimmune T cells. Unless these T cells are responsible for controlling the immune system or are fighting a virus."

"Another fact about science is that most new findings result in more questions being asked. For example the identification of a new 'at risk genetic variant' opens up a whole new avenue of research and results in many more questions."

"Please let me know if this post was too complex for you."

Extra reading: T-cells, CD4, CD8, CD6, genome wide association studies (GWAS)