With MS, the protective layer around nerves, known as the myelin sheath, becomes damaged.

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The disease hinders development of the myelin sheath, a fatty covering that protects the brain's nerve fibers.

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Pelizaeus-Merzbacher disease (PMD) is one of many leukodystrophies in which patients struggle to produce the myelin sheath.

BBC: Nerves

In the late 1980s a young neuroscientist named Martin Schwab, now a professor at the University of Zurich and the Swiss Federal Institute of Technology, suspected the culprit was the spinal cord's myelin, the insulating sheath that surrounds nerves.

FORBES: Health

In MS, the protective sheath or layer around nerves, called myelin, comes under attack which, in turn, leaves the nerves open to damage.

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