DNA Sequencing And A Medical Mystery: Boy's Illness Leads To Diagnostic Odyssey : Shots - Health News Alex Yiu was born a seemingly healthy baby. But by age 2, his muscle control and speech were deteriorating. His baffling condition took a decade to diagnose. The reanalysis of a DNA test was the key.
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A Boy's Mysterious Illness Leads His Family On A Diagnostic Odyssey

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A Boy's Mysterious Illness Leads His Family On A Diagnostic Odyssey

A Boy's Mysterious Illness Leads His Family On A Diagnostic Odyssey

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Thousands of children in the United States are born every year with mysterious medical conditions. Many of their families search for answers in what can be a diagnostic odyssey. NPR science correspondent Richard Harris has the story of one family whose odyssey took a dozen years.

RICHARD HARRIS, BYLINE: When Alex Yiu was born 14 years ago, he seemed like a typical healthy kid. But starting at the age of 2, his mother, Caroline Cheung-Yiu, started noticing things that were amiss - first, little things, then much bigger problems. As part of her quest to understand Alex's illness, she documented those in a brief video, which she plays for me in San Diego, which is not far from their home.

So how old is he here?

CAROLINE CHEUNG-YIU: He's 5. So this is kindergarten. It was kindergarten open house.

HARRIS: Alex is happily swinging on a play structure and smiling as he slips down the slide. But over the next 12 months, Alex became increasingly clumsy and kept falling over.

CHEUNG-YIU: And then by first grade, at 6, he stopped walking.

HARRIS: His trunk got progressively weaker, so he had to be braced in his wheelchair.

CHEUNG-YIU: And then here, he's losing arm control; he can't control his arms.


ALEX YIU: (Unintelligible).

CHEUNG-YIU: And his speech is - his speech is going.


ALEX: (Unintelligible).

HARRIS: Doctors ran test after test and couldn't figure it out. His parents found three different sets of researchers willing to sequence his DNA, but no mutations stood out to explain his failing health.

CHEUNG-YIU: And then in 2017, his lung collapsed, and so he needs now a BiPAP ventilator to breathe, you know.

HARRIS: Was it hard for you to watch that video?

CHEUNG-YIU: Yes and no. You know, he used to be able to talk and walk and play, and now, he can't. But we try to focus on the now and what we can do to make his life the best that it can be.

HARRIS: The video also helped Caroline Cheung-Yiu solve Alex's mystery. When she played it for doctors and researchers, they frequently became engaged in this heart-wrenching medical mystery. And one of those many connections finally paid off.

CHEUNG-YIU: And it was actually by chance that he got diagnosed.

HARRIS: Alex's DNA had been sequenced and analyzed back in 2012 by a nonprofit institute in Phoenix called TGen. Scientists at the time couldn't pin down a cause, but they kept his DNA data on file.

Then, in September of last year, Keri Ramsey at TGen says her boss asked her to reanalyze one patient's DNA in preparation for another medical appointment. But the request had a typo.

KERI RAMSEY: Instead of, you know, asking for the patient that he was actually seeing in his clinic, he put down Alex's family's number.

HARRIS: There are thousands of cold cases like Alex's, and the databases cataloging genetic diseases are constantly being updated. So scientists rerun the analysis when they can, and every so often, a cold case gets solved.

Ideally, this should be an automated process, but the technology is not quite there. This time, when Ramsey ran the analysis again, one of Alex's DNA variants matched up with a disease in the database.

RAMSEY: I looked over at the disorder that had - was associated with this gene, and it fit Alex's set of symptoms. And I was completely shocked. Like, why did we miss this? You know, what was going on here?

HARRIS: It turns out that a freshly published research paper had been catalogued in the genetics database, and it had drawn a link between Alex's symptoms and a particular mutation.

RAMSEY: I immediately went into our medical director and said, I think I know what's going on with Alex. And he was like, why did you go back and analyze Alex's data? And I said, well, you asked me to (laughter).

HARRIS: Word spread quickly back to Caroline Cheung-Yiu and her husband.

CHEUNG-YIU: And we got a call from our neurologist, and they said they found it. It's - the paper was just published in July of 2018, last year.

HARRIS: And so now that you know what the diagnosis is, how does that change your life and Alex's life?

CHEUNG-YIU: Well, the day in and day out care and what's going on with him is the same. However, now, I can say, well, this is the gene that's causing it. Then we can target that and look into that.

HARRIS: What do you expect Alex's life to be like going forward?

CHEUNG-YIU: At this point, he is so sick that I don't think it's reversible. But if there is something that can relieve his symptoms to make his quality life a little bit better, that would be great.

HARRIS: It's more than just a personal relief to end this diagnostic odyssey. Cheung-Yiu built a support group to help other patients who are going through what she is and who now have a better idea about what to expect. Richard Harris, NPR News.

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