"In people with the DRB1 variant associated with MS, it seems that vitamin D may play a critical role," says co-author Dr Julian Knight. "If too little of the vitamin is available, the gene may not function properly."
"We have known for a long time that genes and environment determine MS risk," says Professor George Ebers, University of Oxford. "Here we show that the main environmental risk candidate vitamin D and the main gene region are directly linked and interact."
Professor Ebers and colleagues believe that vitamin D deficiency in mothers or even in a previous generation may lead to altered expression of DRB1*1501 in offspring.
The finding that the environment interacts directly with the background genetics of MS complements research recently published in Human Molecular Genetics by Professor Ebers's group. There, they showed that environment changes to the same gene region can increase the risk of developing MS even further and can be inherited. These so-called "epigenetic effects" are being seen as increasingly important by scientists and there may be ways in which the effects reported in these two papers are related.
"Epigenetics will have important implications, not only for MS, but for other common diseases," says Professor Ebers. "For mothers, taking care of their health during their reproductive years may have beneficial effects on the health of their future children or even grandchildren."
The authors hypothesise that this gene-environment interaction may affect the ability of the thymus, a key component of the immune system, to perform its regular tasks. The thymus produces an army of T cells, which identify invading pathogens, such as bacteria and viruses, and attack and destroy them. There are millions of different T cells, each designed to recognise a specific pathogen, but there is a risk that one type might mistakenly identify one of the body's own cells or proteins.
|Contact: Catriona Silvey|
Public Library of Science