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0:00
This episode was made in partnership with The Kavli Prize. The Kavli Prize honors scientists for breakthroughs in astrophysics, nanoscience and neuroscience, transforming our understanding of the big, the small, and the complex. [♪ INTRO] Sometimes, two researchers find themselves discovering the same thing at the same time. And historically, this has led to a race for one scientist to be recognized over the other. This has been the source of countless near-misses for prizes and other accolades.
0:29
But some researchers are lucky enough to make a discovery at the same time as another scientist who’s up to collaborate instead of compete. And that is the story of Drs. Harry Orr and Huda Zoghbi. When they realized in 1988 that they were both zeroing in on the same source of a rare and deadly disease now called SCA1, they decided to work together. And two heads were totally better than one. Their collaboration continued for decades and brought them both recognition
0:56
as winners of the 2022 Kavli Prize. SCA1 is a neurodegenerative disease characterized in 1950, by Dr. John Schut. It causes brain cells to die off. And it especially affects the cells in the brain’s movement centers, which impact somebody’s ability to walk without losing balance or do things like breathe. So, it’s about as serious a condition as you’d think. Dr. Schut actually had SCA1, and eventually, he passed the scientific baton to his nephew, who then recruited Dr. Harry Orr to
1:26
help him learn what leads to the disease. But while Orr was on that quest, a young researcher named Dr. Huda Zoghbi realized that she was working on the same puzzle and suggested that they collaborate. And so, this scientist duo was born!. Together, they observed trends in people diagnosed with SCA1. For example, people usually start to notice their symptoms around the time they’re 35 years old, but the age of onset really varies.
1:51
Some first notice symptoms when they’re four, and others when they’re 70. After years of poring over case studies, Drs. Zoghbi and Orr discovered the key to why: There seems to be a genetic aspect to this disease. The younger-onset cases usually come from families with a history of SCA1. This is a phenomenon called anticipation, when a genetic condition gets more extreme as generations go on. So now, what this team needed to figure out was what was different about these patients’ DNA.
2:20
To answer that, they turned to similar diseases that they knew more about. Specifically, certain cases of SCA1, where Zoghbi and Orr observed anticipation, reminded them of the same patterns in another neurologic disease, Myotonic dystrophy, which weakens muscles and makes them harder to control. At that time, researchers had a pretty good idea that myotonic dystrophy was caused by an expansion of the repeated segments of DNA in a person’s genetic code. So Drs.
2:47
Zoghbi and Orr looked for those repeat expansions in the DNA of people who’d been diagnosed with SCA1, and found them!. For context, your DNA is made of tons of combinations of four nucleotides, called A, C, G, and T for short. Within genes that are coding for proteins, these DNA bases are arranged in segments of three that form this code. In this case, Orr and Zoghbi discovered that most people’s sixth chromosome had a gene with nucleotides C-A-G, coding for the amino acid glutamine,
3:16
repeated anywhere from 19 to 36 times. But people diagnosed with SCA1 have C-A-G repeated anywhere from 43 to 81 times. And when their cells read that code, those extra repeats led to a protein with a longer glutamine tract that leads to toxicity in the brain. With this discovery in 1993, Orr and Zoghbi had found the root of SCA1! But they did not have a cure. There were still a lot more questions. Like, 43 to 81 C-A-G repeats? That’s a huge variation in the number of repeated segments
3:50
a person with SCA1 could have in their DNA. Some people diagnosed are way closer to the average number of repeats than others. And Zoghbi and Orr found that this also probably has to do with anticipation. They found that later generations of families with this disease had more C-A-G repeats, which also explains why children in these families show symptoms earlier than their ancestors. And since the number of repeats goes up as the generations go on,
4:15
this means SCA1 has the potential to keep getting worse and worse with younger and younger mortality. But Zoghbi and Orr are working to put a stop to it. Twenty years after they discovered the genetic root of SCA1, they figured out how to turn off the disease-causing gene and slow the effects of the disease… at least, in mice. They created genetically-modified mice whose SCA1 gene could not be read. That meant their bodies didn’t make as many of those extra-long proteins.
4:43
And as a result, these mice didn’t show the symptoms of SCA1 until later in life, and they were able to live twice as long without nearly as much motor impairments as the SCA1 model mice. Now, one thing about these mice is that they were mice, not humans, which means the results might not translate to us. And the mice were genetically-engineered before they were born to have fewer SCA1 symptoms, so this isn’t a solution for people who are diagnosed with SCA1 today.
5:08
But researchers are making progress so that this disease might not be so deadly in the future. The team is also using new ways to decrease the amount of the disease-causing protein so that this therapy can be translated to people. For their contributions toward a better understanding of SCA1 and their strides toward a cure, Drs. Orr and Zoghbi are recipients of the 2022 Kavli Prize in Neuroscience. They were able to accomplish so much by working together on each of these projects over decades.
5:35
By teaming up instead of racing each other to the finish line, these scientists, and everyone in their labs, learned about human bodies and genetics. And in the future, these discoveries might be saving lives. [♪ OUTRO]
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