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In 1963, a 21-year-old physicist
named Stephen Hawking
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was diagnosed with a rare
neuromuscular disorder
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called amyotrophic lateral sclerosis,
or ALS.
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Gradually, he lost the ability to walk,
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use his hands,
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move his face,
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and even swallow.
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But throughout it all,
he retained his incredible intellect,
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and in the more
than 50 years that followed,
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Hawking became one of history’s most
accomplished and famous physicists.
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However, his condition went uncured
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and he passed away in 2018
at the age of 76.
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Decades after his diagnosis,
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ALS still ranks as one
of the most complex,
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mysterious,
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and devastating
diseases to affect humankind.
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Also called motor neuron disease
and Lou Gehrig’s Disease,
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ALS affects about two out of every
100,000 people worldwide.
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When a person has ALS,
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their motor neurons,
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the cells responsible for all voluntary
muscle control in the body,
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lose function and die.
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No one knows exactly why
or how these cells die
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and that’s part of what
makes ALS so hard to treat.
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In about 90% of cases,
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the disease arises suddenly,
with no apparent cause.
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The remaining 10% of cases are hereditary,
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where a mother or father with ALS passes
on a mutated gene to their child.
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The symptoms typically first appear
after age 40.
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But in some rare cases, like Hawking’s,
ALS starts earlier in life.
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Hawking’s case was also a medical marvel
because of how long he lived with ALS.
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After diagnosis, most people with
the disease live between 2 to 5 years
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before ALS leads to respiratory problems
that usually cause death.
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What wasn’t unusual in Hawking’s case
was that his ability to learn,
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think,
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and perceive with his senses
remained intact.
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Most people with ALS do not experience
impaired cognition.
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With so much at stake
for the 120,000 people
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who are diagnosed with ALS annually,
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curing the disease has become one of
our most important scientific
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and medical challenges.
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Despite the many unknowns,
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we do have some insight into how ALS
impacts the neuromuscular system.
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ALS affects two types of nerve cells
called the upper and lower motor neurons.
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In a healthy body,
the upper motor neurons,
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which sit in the brain’s cortex,
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transmit messages
from the brain to the lower motor neurons,
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situated in the spinal cord.
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Those neurons then transmit
the message into muscle fibers,
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which contract or relax in response,
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resulting in motion.
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Every voluntary move we make occurs
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because of messages transmitted
along this pathway.
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But when motor neurons degenerate in ALS,
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their ability to transfer
messages is disrupted,
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and that vital signaling system
is thrown into chaos.
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Without their regular cues,
the muscles waste away.
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Precisely what makes
the motor neurons degenerate
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is the prevailing
mystery of ALS.
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In hereditary cases, parents pass genetic
mutations on to their children.
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Even then, ALS involves multiple genes
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with multiple possible impacts
on motor neurons,
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making the precise triggers
hard to pinpoint.
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When ALS arises sporadically,
the list of possible causes grows:
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toxins,
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viruses,
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lifestyle,
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or other environmental factors
may all play roles.
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And because there are
so many elements involved,
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there’s currently no single test that
can determine whether someone has ALS.
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Nevertheless, our hypotheses
on the causes are developing.
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One prevailing idea is that certain
proteins inside the motor neurons
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aren’t folding correctly,
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and are instead forming clumps.
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The misfolded proteins and clumps
may spread from cell to cell.
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This could be clogging up normal
cellular processes,
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like energy and protein production,
which keep cells alive.
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We’ve also learned that along with
motor neurons and muscle fibers,
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ALS could involve other
cell types.
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ALS patients typically have inflammation
in their brains and spinal cords.
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Defective immune cells may also play
a role in killing motor neurons.
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And ALS seems to change the
behavior of specific cells
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that provide support for neurons.
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These factors highlight
the disease’s complexity,
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but they may also give us a fuller
understanding of how it works,
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opening up new avenues for treatment.
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And while that may be gradual,
we’re making progress all the time.
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We’re currently developing new drugs,
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new stem cell therapies
to repair damaged cells,
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and new gene therapies
to slow the advancement of the disease.
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With our growing arsenal of knowledge,
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we look forward to discoveries
that can change the future
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for people living with ALS.