Hi Simon,

Thanks for the kind words. A complete understanding of how DR2b limits severity of MS by controlling the immune response should give insight into potential therapeutic strategies to combat the disease. (I'm curious whether this study implies that the genes which lead to autoimmune disease are selectively advantageous, in (e.g.) the way the genes which cause sickle cell anemia provide protection against malaria.)

However the DR2 haploytpe has long been known to confer MS susceptibility, and as Barbara notes the genetics of MS is complex, with multiple genes at work. Not everyone with MS carries DR2 genes.

Identical twin studies have shown the extent to which MS is genetic: if the disease were strictly genetic, 100% of identical twins would get the disease if the other twin got it. But in fact about 25% of twins will develop MS if their (monozygotic) twin sibling develops MS.

(As you may remember, the phase III trial of the new MS drug MBP8298 is only accepting patients with HLA-DR2 or HLA-DR4 genes, which 70 - 80% of MS patients carry.)

Mark