Multiple Sclerosis Biased Against Women
The medical journal Neurology reported findings that start to answer the question, why is there an increase in prevalence of multiple sclerosis in women?
100 years ago MS was equally likely to strike men as well as women according to researchers George C. Ebers and colleagues. However currently, women are affected more often than men. Ebers found a ratio of nearly 2:1, female versus male patients.
Past research directed at locating a genetic anomaly on the female X chromosome showed no genetic significance towards the disease. Ebers et al. instead studied the area in the genome called the ‘major histocompatibility complex’ or MHC. This area of DNA is highly polymorphic, meaning there is a wide diversity from person to person. And the MHC genes tend to pass down generations as one big bunch of intact genes.
The study consisted of more than 7,000 people and considered their genetics as well as epigenetics—(environmental factors affecting genes, outside of the actual DNA) that could account for the female bias of the disease. Also the study diagrammed the relatedness of the members of each family.
They found that a particular variation in the MHC portion of the genome titled HLA-DRB1*15 is particularly involved in the female bias. When this female-loving aberration is found within two affected members of a family they most often see the disease pass down generations between members of the family who are 1 and 2 steps removed from each other. (Related as aunts-uncles-nieces-nephews or as cousins.) Transference between generations was shown to be less likely within closer related members. (Such as mother-daughter.)
This strange result Ebers explains is likely an epigenetic outcome. Something in the environment is acting upon the genes in such a way as to alter the way the proteins function.
Medpage Today states:
“The researchers suggested that DNA methylation — which can be affected by environmental factors and is heritable — could be the "epigenetic mark" responsible for these effects, although they acknowledged that supporting experimental data were still lacking.
In an accompanying editorial, a Mayo Clinic researcher pointed out that epigenetics provide the only plausible mechanism that could account for the onset of female predominance in MS.”
Ebers and colleagues follow up with the fact that other diseases similar to multiple sclerosis (also autoimmune) including systemic lupus erythematosus and rheumatoid arthritis, both affect far more women than men.
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