A rare genetic condition that causes sleep difficulties, memory loss (dementia) and involuntary muscles twitching has no cure and gets worse over time and eventually leads to death.  Symptoms of fatal familial insomnia (FFI) can only be slowed through treatment temporarily, according to Cleveland Clinic.  FFI affects an estimated one to two people per million every year, as per data provided by the National Organisation of Rare Disorders.  It passes from parent to child and between 50 and 70 families around the world are suspected to carry the genetic mutation that causes the condition. A neurodegenerative prion disease, FFI is caused by a mutation in the PRNP gene that generates prion protein. The prions are misfolded versions of normal proteins. Their unusual shape causes toxicity to cells in the body, more particularly neurons in the brain, as per . The thalamus is one of the tissues that is damaged and it is the region of the brain that regulates an array of body functions including sleep, temperature and appetite. Children need to inherit only one mutant PRNP gene from a parent to get the condition but in rare cases, people can develop mutations in the PRNP gene even if they have no family history of FFI. They then pass this mutation on to their children. The most notable FFI symptom is insomnia or being unable to fall or stay asleep. The symptoms worsen with the passage of time and at one point, the patient cannot sleep at all. These patients also experience memory loss, high blood pressure, hallucinations and involuntary jerking or twitching of the muscles. They can also sweat profusely and lose coordination and concentration. These symptoms begin around the age of 40 but can develop in a person’s 20s or as late as 70. Patients eventually end up in a coma-like state and usually die within nine to 30 months after their symptoms emerge. There is no treatment to cure the disease but the symptoms can only be slowed down.