Richard Bedlack has treated more than 2,000 patients with ALS, the neurological condition also known as Lou Gehrig’s disease. Almost without exception, his patients get worse over time and eventually die.

Now, Dr. Bedlack, longtime head of Duke University’s ALS clinic, is focusing on a different kind of patient: someone who seems to be getting better.

ALS, or amyotrophic lateral sclerosis, progressively robs people of the ability to move their muscles and is fatal, usually within two to five years.

But in a small number of cases—Dr. Bedlack says he has verified 23 so far—patients report unexpectedly regaining lost motor functions for at least a year. Some attribute their improvement to supplements or experimental therapies, but acknowledge they can’t be certain why they started to improve.

Dr. Bedlack believes that studying these so-called “ALS reversals” and trying to determine what, if anything, separates these individuals from the overwhelming majority of others may lead to new understanding of the disease and, potentially, new therapies.

The effort to study people who seem to defy medical odds isn’t limited to ALS. The Resilience Project, started in 2014, is examining the genomes of healthy individuals, trying to find people who aren’t sick despite having gene mutations that should cause disease.

For over a decade, a multi-institution research consortium has followed so-called “elite controllers,” people infected with HIV who somehow naturally control the virus without anti-retroviral medications and don’t develop AIDS. Studies of patients by the International HIV Controllers Consortium and other groups helped identify a genetic signature associated with controllers, and experimental therapies are now being tested.

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