Retroviruses are viruses that have integrated into our genome and are passed on to our offspring. By analyzing DNA investigators have found that variations in a gene called TRIM5 and a retroviral insertion site correlated with MS. Clearly these results need to be confirmed. If they are confirmed we will need to incorporate retroviruses into our models of MS.
Nexø BA, et al. The Etiology of Multiple Sclerosis: Genetic Evidence for the Involvement of the Human Endogenous Retrovirus HERV-Fc1.PLoS One. 2011 Feb 2;6(2):e16652.