Name: How this disease changes the shape of your cells - Amber M. Yates
Uploaded: 2020-03-19T19:31:27.000Z
Duration: 4 min 41 s
Description: Thousands of YouTube videos with English-Chinese subtitles! Now you can learn to understand native speakers, expand your vocabulary, and improve your pronunciation...

You probably don’t think much about the bodies of these building blocks,

but at the microscopic level, small  changes can have huge consequences.

And while some adaptations change  these shapes for the better,

others can spark a cascade of  debilitating complications.

This is the story of sickle-cell disease.

Sickle-cell disease affects the  red blood cells,

which transport oxygen from the lungs  to all the tissues in the body.

red blood cells are filled with hemoglobin proteins to carry oxygen molecules.

inside the red blood cell’s pliable,  doughnut-like shape,

to accommodate even the  tiniest of blood vessels.

a single genetic mutation alters the structure of hemoglobin.

these mutated proteins lock  together into rigid rows.

Rods of hemoglobin cause the cell  to deform into a long, pointed sickle.

These red blood cells are  harder and stickier,

and no longer flow smoothly through  blood vessels.

sometimes blocking the vessel completely.

This keeps oxygen from reaching a variety of cells,

experienced by people  with sickle-cell disease.

Starting when they’re  less than a year old,

patients suffer from repeated episodes of stabbing pain in oxygen-starved tissues.

determines the specific  symptoms experienced.

A blockage in the spleen,  part of the immune system,

puts patients at risk for  dangerous infections.

A pileup in the lungs can produce  fevers and difficulty breathing.

A clog near the eye can cause vision  problems and retinal detachment.

And if the obstructed vessels  supply the brain

Worse still, sickled red blood cells  also don’t survive very long—

just 10 or 20 days, versus a  healthy cell’s 4 months.

means that patients live with a constantly depleted supply of red blood cells;

Perhaps what’s most surprising  about this malignant mutation

is that it originally evolved as a beneficial adaptation.

Researchers have been able to trace the origins of the sickle cell mutation

to regions historically ravaged  by a tropical disease called malaria.

Spread by a parasite found  in local mosquitoes,

malaria uses red blood cells as incubators

to spread quickly and lethally  through the bloodstream.

However, the same structural changes that turn red blood cells into roadblocks

also make them more resistant to malaria.

And if a child inherits a copy of the mutation from only one parent,

there will be just enough abnormal  hemoglobin

to make life difficult for the  malaria parasite,

while most of their red blood cells retain their normal shape and function.

sickle cell mutation offered a serious  evolutionary advantage.

it became clear that inheriting the  mutation from both parents

Today, most people with  sickle-cell disease

can trace their ancestry to a country where malaria is endemic.

And this mutation still plays a key role in Africa,

where more than 90% of malaria  infections occur worldwide.

Fortunately, as this “adaptation” thrives,

our treatment for sickle cell continues  to improve.

For years, hydroxyurea was the only  medication available

blunting symptoms and  increasing life expectancy.

Bone marrow transplantations  offer a curative measure,

but these procedures are  complicated and often inaccessible.

But promising new medications  are intervening in novel ways,

like keeping oxygen bonded to  hemoglobin to prevent sickling,

or reducing the stickiness  of sickled cells.

has raised the possibility of enabling  stem cells to produce normal hemoglobin.

in the areas most affected by malaria and sickle cell disease,

for more patients with this  adverse adaptation.

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How this disease changes the shape of your cells - Amber M. Yates

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