Not MS, however something of this nature may eventually explain female prevalence. Since women have two x chromosomes, men one...and this genetic variant is only found on the x chromosome.
The Mayo team carried out a detailed genetic analysis of patients with Alzheimer's disease.
They identified a particular variant of a gene called PCDH11X which appeared to be closely linked to a higher risk of the disease.
However, further analysis showed that the association was almost entirely restricted to women.
PCDH11X controls production of a protein called a protocadherin, part of a family of molecules that help cells in the central nervous system to communicate with each other.
Some evidence has suggested that protocadherins may be broken down by an enzyme which has been linked to some forms of Alzheimer's disease.
Lead researcher Dr Steven Younkin said it was likely that many genes contributed to the overall risk of Alzheimer's, and that age was probably a more significant factor.
He said: "It is exciting to find a new gene for Alzheimer's, particularly the first that has a gender-specific effect, but we have a lot more work to do to resolve the complex genetics of the disease."