Humans are all almost exactly the same... almost - Greg Foot

213,916 views ・ 2023-05-09

TED-Ed


Please double-click on the English subtitles below to play the video.

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Medical science has a problem— it’s missing something.
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Something that means that not only is it harder to find
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the causes of some diseases—
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and effective ways to treat them—
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some diseases are getting overlooked entirely.
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It turns out what it’s missing could be you—
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but I’ll get to that in a bit.
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Because first, a story.
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Or 8 billion stories, to be precise.
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See, our DNA is our body's instruction manual, sure.
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But it’s also a history book that records our own, unique genetic story.
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All our stories begin around 300,000 years ago
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when humans arose in Africa.
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Some genetic stories tell of leaving a couple of hundred thousand years later,
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journeying into Europe, East Asia, or the Americas.
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Some genetic stories speak of expanding empires.
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Others the diseases we evolved to ward off,
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and some the simple act of settling down, raising cattle, and drinking their milk.
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Each of our genetic stories are different,
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but maybe not as different as you might expect.
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We share 99.9% of our DNA with each other.
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Our stories are 99.9% identical,
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but that 0.1% difference is incredibly powerful.
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In that tiny difference between our genetic stories
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is where we have the potential to develop better treatments for diseases—
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treatments that work for everyone.
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But medical science isn’t currently reading all those stories.
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To explain let me tell you how researchers work out the causes of diseases,
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and develop and test the effectiveness and safety of new treatments.
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To find out the causes of a particular disease,
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researchers find lots of people who have that condition
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and comb through their genetic stories.
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They look for little variations they share—
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little bits of their DNA stories that are spelt differently.
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If they find some, then they try all sorts of different ways
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of dealing with the effect of them.
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And if that uncovers something that looks promising,
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they then run a clinical trial to see if it actually is.
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In phase one, a small group of volunteers try the treatment.
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Well, often only half of them do,
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with the other half getting a placebo that does absolutely nothing.
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If there aren’t any notable side effects at the target dose,
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the treatment is cleared to move on to the next stage of the clinical trial.
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Phase two, this time with a bigger group of participants
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who all have the condition the researchers hope the drug will treat.
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If the drug appears effective, it moves on to phase three,
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with more participants trying it for even longer.
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Only after all this is the new treatment then reviewed
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and— hopefully— approved for use by us, the general population.
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But there's a problem with it.
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Here is the ethnicity of lots and lots of people used to recently find
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the causes of various diseases.
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And here is how that compares to the ethnic diversity
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of the world’s population.
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Spot the difference?
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The genetic stories that researchers are combing through are heavily biased
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to those of people from European descent.
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Which means that if you’re searching
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for those disease-causing bits of DNA to target new drugs against,
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and you're mainly reading the stories of people of European descent,
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you might completely overlook key bits in the stories
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of other diverse groups that tell of, say,
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a changed risk of disease or even shed light on how a disease occurs—
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for example, scientists may not have found the mutation
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that causes sickle cell disorder
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if we’d only looked in the stories of people of European descent.
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And the thing is, what medical science is missing doesn't end there.
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When new treatments or medical devices are being tested,
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they need to be tested on everyone that may use them.
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If the genetic stories involved don’t reflect the breadth of stories
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in our worldwide library then, again, something might be missed.
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Take, for example, the medicine Warfarin; used to prevent blood clots.
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Researchers have found that, to produce the same effect,
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most people of East Asian descent need a lower dose
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than some people of European descent,
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and most people of African ethnicity need a larger dose.
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Which means the dose that works best for someone
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may vary according to their ethnicity.
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It’s this kind of important information that can be missed if clinical trials
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don’t include people from across a range of ethnicities.
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So what’s the solution?
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Well, it’s quite simple... in theory.
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In order to develop treatments that work better for everyone,
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we need to involve everyone’s stories in medical research—
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in the early stage research, in the drug development process,
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and right through the clinical trial.
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The good news is that more and more people are thinking about this.
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For example, cancer researchers at University College London
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researching genetic markers for cancer want to analyze tissue samples
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from a wide range of ethnicities so that the biomarkers of cancer they identify
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will be relevant for people from as many ethnicities as possible.
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Bottom line: medical science needs to ensure
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it’s got the best library it can have—
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the one with the widest collection of genetic stories possible,
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so that everyone’s story can be considered—
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including yours.
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That is the only way to ensure everyone, everywhere
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can get the best medical treatment they possibly can.
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