In 2017, two parents asked scientist Stanley Crooke to create treatments for their children's rare mutations. Years later, a custom drug cut one boy's seizures by 90% and helped him walk on his own for the first time

Medicine is undergoing a profound transformation by shifting focus from populations to individual patients. A novel custom drug for rare genetic mutations recently enabled a paralyzed teenager to walk again. Seventeen-year-old Connor Dalby previously suffered up to one hundred violent daily epileptic seizures. His condition stemmed from an ultra-rare mutation in the vital SCN2A brain gene. Commercial pharmaceutical companies initially refused to build a specialized treatment for a single child. Scientists...