May 7, 2010 – Another study gives weight to the thesis of environmental factors to explain the appearance of multiple sclerosis, according to American research published in a recent edition of the journal Nature1. The researchers do not question the genetic predisposition, but they believe that it is not the only one involved.
They sequenced the genomes of 3 pairs of identical twins, of which only 1 member was affected. Despite the most advanced sequencing techniques, the researchers found no genetic difference that could justify one of the twins being affected while the other remains perfectly healthy.
We know that in identical twins – those whose genetic background is identical – the genetic predisposition to multiple sclerosis does not necessarily result in the onset of the disease in both members of the couple. In 70% to 75% of cases, only 1 of the 2 twins is affected.
The researchers therefore conclude that an environmental factor could act as a trigger for the disease. Who? The study did not look into the question, but several risk factors have been studied in recent years: insufficient intake of vitamin D, smoking cigarettes, consuming a lot of animal fat, being in contact with chemical solvents in the environment. of work. It is also believed that a viral infection could trigger the autoimmune reaction that characterizes multiple sclerosis.
But there is still the possibility that something has escaped the genetic analysis carried out by the American experts. Genome sequencing techniques are still at an embryonic stage, despite the advances made in recent years.
Pierre Lefrançois – PasseportSanté.net
1. Baranzini SE, Mudge J, van Velkinburgh JC, et al. Genome, epigenome and RNA sequences of monozygotic twins discordant for multiple sclerosis. Nature. 2010 Apr 29; 464 (7293): 1351-6.
