Fatal familial insomnia is a rare genetic disease that interferes with sleep and eventually leads to death. The disease is the result of mutations in a certain protein, which cause plaques to build up in the thalamus, the brain region responsible for sleep regulation. Patients initially suffer from insomnia and progressively develop more serious problems—including hallucinations, rapid weight loss, and dementia—before dying. In how many families has the gene that causes the disease been found? Discuss
Source: The Free Dictionary