Herrera BM, Ramagopalan SV, Lincoln MR, et al. Parent of origin effects in MS. Observations from avuncular pairs. Neurology; 2008: 71:799-803.
Genetics review of MS. The risk for a first degree relative of an MS proband of 3-5 % is 30-50 times higher than the general population (0.1%) and vary by relatedness and number of affected individuals in family. There is agreement that there are a number of genes of small effect interacting with the environment.
This study used avuncular pairs and found a strong predilection for maternal gene of origin in 871 families surveyed. After removing families where the parent had MS, there were 807 families with 938 avuncular pairs. There were 526 maternal pairs, and 412 paternal pairs which was highly significant (McNemar test).
Moreover, the niece to nephew ratio of 2.67:1 was higher than the aunt/uncle ratio of 1.85. In paternal families only, the ratio was higher in families with an affected aunt.
Authors note that in Canada the increase is MS is noted to be due to increased number of females.
The gene of locus is not known.
Authors also note the May birthday peak and November birthday nadir for MS births.