Here, in layman's terms-- I'll make it clear.
Having HLA-DRB 1501, which is a genetic marker that shows up in northern Europeans, increases your risk for having MS by three-fold.
A region at or near the HLA-DRB1 locus in the MHC influences the risk of MS. HLA-DRB1 has over 400 different alleles. The dominant haplotype of Northern Europe, marked by the presence of DRB1*1501, increases risk of MS by 3-fold. The environment also plays a key role in MS. The most striking illustration of this is the geographical distribution of the disease in populations matched for ethnicity.
http://www.plosgenetics.org/article/inf ... en.1000369
This means that this locus is associated with risk of getting MS. It doesn't mean it causes MS, or it's always found in pwMS....it just means that this particular allele makes you more susceptible to getting MS. And lots of things come into play, like environmental issues, or where you live.
It's like saying, (and this is a made up, for-instance) people from northern Europe have 3 times the risk of getting MS than people from Central America. That doesn't mean you can't get MS if you live in Brazil, and it doesn't mean you will get MS if you live in Ireland. It's just a way of looking at the genome and MS risk. OK?
OK, are we clear so far?...so, the Buffalo doctors looked for this particular genetic marker in their patients. They found it in 53% of the pwMS they tested. They found it in 33% of the people with CCSVI. They also found it in a third of the normal population.
So? So what? They found a marker that is associated with northern Europeans that can increase risk of MS. It was more prevalent in pwMS than pwCCSVI by 20%. But, it was also found in 30% of normals....
this is not a negative study that disproves anything about CCSVI, this is an interesting study that needs more research, according to the last paragraph of the paper.
cheer