 Vitamin D helps control MS gene
Source: BBC News Date: 02/06/2009
The first evidence of how vitamin D deficiency and genetics interact to increase the risk of multiple sclerosis has been reported by researchers.
A UK and Canadian team found that vitamin D helps to control a gene known to increase MS risk, the PLoS Genetics journal reports.
It suggests that vitamin D supplements taken during pregnancy and early in life could prevent the disease.
More than 85,000 people in the UK are thought to have MS.
The
condition results from the loss of nerve fibres and their protective
myelin sheath in the brain and spinal cord, causing neurological damage.
It
is not entirely clear what causes MS but other research has suggested
vitamin D, produced in the body through exposure to sunlight, plays a
part.
Specifically there is evidence that populations from
Northern Europe have an increased risk of developing MS if they live in
areas receiving less sunshine.
Various pieces of research have also pointed to genetic causes.
In
the latest study, researchers at the University of Oxford and
University of British Columbia looked at a section of the genome on
chromosome six which had been shown to have the strongest effect on MS
risk.
While one in 1,000 people in the UK is likely to develop
MS, this number rises to around one in 300 among those carrying a
single copy of the gene variant - known as DRB1*1501 - and one in 100
of those carrying two copies.
The researchers found that
proteins activated by vitamin D in the body bind to a particular DNA
sequence next to the gene, altering its function.
They believe
that vitamin D deficiency in mothers or even in a previous generation
may lead to altered expression of the gene in their offspring.
Immune system
Exactly
how the gene-environment interaction alters MS risk is yet to be
determined; one explanation could be an effect on the thymus - a part
of the immune system which produces T cells to attack invaders such as
bacteria and viruses.
It is thought that in people who carry the
gene variant, a lack of vitamin D during early life might impair the
ability of the thymus to delete rogue T cells, which then go on to
attack the body, leading to a loss of myelin on the nerve fibres.
Co-author,
Professor George Ebers, from the Wellcome Trust Centre for Human
Genetics, at the University of Oxford, said it had been known for a
long time that genes and the environment determine MS risk.
"Here
we show that the main environmental risk candidate - vitamin D - and
the main gene region are directly linked and interact."
Study
leader, Dr Sreeram Ramagopalan, added: "Our study implies that taking
vitamin D supplements during pregnancy and the early years may reduce
the risk of a child developing MS in later life."
Simon
Gillespie, chief executive of the MS Society, said: "These remarkable
results tie together leading theories about the environment, genes and
MS but they are only part of the jigsaw.
"This discovery opens up new avenues of MS research and future experiments will help put the pieces together."
The
government already advises that pregnant and breastfeeding women make
sure they get enough vitamin D, taking supplements if necessary.
And it is also recommended that children under five take daily vitamin D supplements.
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