Kelly Berthoud remembers the day in 2019 when her daughter Marley sprouted her first eyebrows. Already four years old at the time, Marley had been hairless for most of her life, one of several characteristics about the young girl that scientists and physicians had spent years working to explain. But with the family ensconced in the living room on that morning just before Christmas, each tiny blonde hair, now growing as the result of an experimental drug Marley had recently started taking, was a gift. “We were sitting on the couch and the sunshine was hitting her just right,” Berthoud recalls. “I remember whipping my head around when I noticed.”
Marley had in fact been born with silver hair, but shortly after, it had fallen out in thick clumps. Her head was also unusually large, and a neonatal MRI revealed that sometime before her birth she had suffered a brain ...
