“In the beginning, my mom’s symptoms were vague: speech disturbances, memory problems, small errors in judgment. She was losing weight without trying.” Vallabh recalled.

Over the next few months, Vallabh said, her mother deteriorated rapidly: “She couldn’t walk or talk or feed herself. She became deeply paranoid and fell into a profound dementia. She went on life support, and died a few weeks later.”

Vallabh’s mother’s illness remained a mystery for several months after her death, until a piece of tissue taken from her brain tested positive for a mutation in a gene called PRNP that is known to cause FFI. Results from an autopsy had also concluded that FFI was a possible cause of death.

“Nobody even for one second suspected fatal familial insomnia, because there’s no sign of neurodegenerative disease in the family,” Vallabh said. There are 28 families worldwide who have the gene for FFI in their bloodlines. Most of them have pedigrees marred by inexplicably premature deaths.

FFI is what’s known as a prion disease, a family of rare progressive neurodegenerative disorders that also includes bovine spongiform encephalopathy, or Mad Cow Disease. In people with FFI and similar diseases, mutated proteins called prions trigger normal proteins in the brain to fold abnormally, destroying brain cells and leaving the brain filled with sponge-like holes. But unlike Mad Cow, which can be acquired by ingesting contaminated beef, FFI is genetic. Children of a parent with FFI have a one in two chance of inheriting a mutated PRNP gene.

Just months after her losing her mother to the disease, Vallabh decided to get herself screened. “Once I knew I was at risk, there was no turning back from the knowledge,” she said.

She, too, harbors the gene, and will almost certainly develop and die from FFI unless treatments are developed that slow or stave off the disease’s progression—and soon. The average age of onset for FFI is 50; Vallabh is 30.

“We didn’t seem to be in a position to do anything about it. The fact that my mom died undiagnosed seemed, to us, the final word on the disease,” Vallabh said. To prepare themselves for what lay ahead, she and her husband began to research the condition.

But as the couple started learning more about FFI and other prion diseases, they slowly became more hopeful. Scientists were looking into treatments, they discovered—which meant that maybe, just maybe, it was possible to change Vallabh’s fate.

“We read everything we could about it, from Wikipedia to scientific papers. We badgered our friends who were scientists. We stayed up discussing what we had learned about the disease that day,” Minikel said. “There was much more research going on, and much more known about prions, than Sonia or I had assumed.”

Vallabh, a Harvard-trained lawyer, began sitting in on science classes at the Massachusetts Institute of Technology. Soon, she left her job in consulting and took a job as a lab technician at the Massachusetts General Hospital’s Center for Human Genetic Research. Minikel, an MIT-educated urban planner, followed soon after. He quit his job as a software engineer and took a job in the same division of Mass. General, analyzing genetic data from people with Huntington’s disease. In September 2014, the couple enrolled in a doctoral program in Biological and Biomedical Sciences at Harvard Medical School.