Women who have multiple sclerosis (MS) are more likely to have a gene associated with multiple sclerosis than men with the disease and it is this gene region where environment interacts with the genetics, according to a study published in the January 5, 2011, online issue of Neurology®, the medical journal of the American Academy of Neurology.
Research has shown that the number of people diagnosed with multiple sclerosis has been rising, and the rate has been rising faster for women than for men.
The cause of multiple sclerosis is not known, but evidence suggests that it is triggered by environmental factors in people who are genetically susceptible to the disease. The main gene associated with multiple sclerosis is the human leukocyte antigen (HLA) class II gene, but most of the risk comes from interaction of both parental genes.
The study examined the HLA genes of 1055 families with more than 1 person with multiple sclerosis in the family. The genes of 7093 people were tested, which included 2127 people with multiple sclerosis. The researchers looked at what the HLA genes were for the people with and without multiple sclerosis, whether people with multiple sclerosis inherited the susceptibility gene from their mother or their father, and what the relationship was between people in the same family with multiple sclerosis.
The researchers found that women with multiple sclerosis were 1.4 times more likely to have the HLA gene variant associated with multiple sclerosis than men with multiple sclerosis. A total of 919 women and 302 men had the HLA gene variant, compared to 626 women and 280 men who did not have the gene variant. This fits with other research by this research group showing that the environment interacts with this gene region to produce modification in risk associated with it. This appears to be an epigenetic mechanism.
"Our findings also show women with the HLA gene variant are more likely to transmit the gene variant to other women in their families than to men," said study author George C Ebers MD FMedSCi, of the University of Oxford in the United Kingdom and a member of the American Academy of Neurology.
The researchers also determined that second-degree relatives such as aunts and their nieces or nephews were more likely to inherit the gene variant than first-degree relatives such as siblings or parents and children.
"It appears that the less the genetic sharing between individuals, the higher the interaction is between female sex and inheritance of the HLA gene variant," said Orhun Kantarci MD, of the Mayo Clinic in Rochester, Minnesota, and a member of the American Academy of Neurology, who wrote an editorial on the study. "These findings pave the way for future studies of these genes, hopefully to advance our understanding of inheritance of complex diseases such as MS."
The study was supported by the Multiple Sclerosis Society of Canada and the Multiple Sclerosis Society of the United Kingdom.
Source: News Release
American Academy of Neurology
January 5, 2011