Carolyn and Cheryl are sisters who have lived with a mortal secret for years. A genetic mutation hangs on their family tree like poison fruit.
It killed their grandfather and their uncle and, in 1999, revealed itself in their mom, Barbara.
"I can remember saying, 'Mom, what's wrong? Mom, why can't you speak?'" said Carolyn.
Barbara couldn't speak because she couldn't sleep — at all. Inside Barbara's brain, a genetic trip wire had been crossed, and in a matter of months, she went from being a vigorous 52-year-old woman to a woman in a coma, emerging only for a few days at the very end of her life.
"They took her intubation out, and she couldn't really talk, because she [was] so dry-throated, and everything," recalled Cheryl. "And she was trying to write. And she wrote 'FFI?'"
FFI is the abbreviation for an extremely rare genetic disease called fatal familial insomnia. Those affected by FFI are forever trying and failing to fall asleep. The disease steals one's sleep, mind and ultimately one's life, and, before dying, one hovers for months in a twilight world.
"And I said, 'That's what they think it is,'" said Cheryl. "She never wanted to talk about it. She never wanted to will it to happen."
"My first thought was how dare she keep this from me," said Carolyn. "I may not have had children if I'd known."
FFI affects approximately 40 families worldwide. Barbara didn't know it when she died, but the odds were 50-50 that she'd passed it on to her daughters.
"Whether I do or do not have this disease, it cannot define me. It cannot define me," said Carolyn.
"It's my story. I get to choose whether to laugh or cry about it. It's my choice. I'm going to laugh about it. It's my day. It's my life," said Cheryl.
Researchers believe a wealthy Italian doctor unknowingly carried the original genetic mutation for FFI, 250 years ago. We don't know his name, but experts simply refer to him as Patient Zero — the first known case of the disease. By the time he died in 1765, he had passed the disease on to his children, and the curse had begun.
In its early stages, family members experienced a kind of insomnia we'd all recognize, but those sleepless nights never ended.
"I'd say, within a month, it's pretty clear that you've got a disease like no other disease," said D.T. Max, who has spent years researching the phenomenon of FFI. His book "The Family That Couldn't Sleep" traces the history of the Italian clan who first carried this cruel disease (CLICK HERE to read an excerpt).
"One, you're not sleeping. Two, you're having difficulty walking. Three, your ability to focus has gone downhill rapidly," he said. "Ordinarily, [by] the ninth month, the disease ends with death."
Many of the afflicted Italian family members were brought to San Servolo — an island asylum just a short boat ride from Venice.
Now a museum, San Servolo remains a haunting place. "There would be howls. There would be people doing uncontrollable behavior. There would be attendants chasing after them," said Max, adding that part of the treatment was simply preventing family members from hurting one another. "Generation after generation of this family was strapped, in the later stages of the disease, to a bed at night."
Records show that, throughout the 18th, 19th and 20th centuries, deaths consistent with FFI ran through the generations of the Patient Zero family.