The name of this illness is hard to meet for the first time, and it describes the sleep problem rather than the whole of it. What families usually want first is the plain shape of the condition, and then someone to talk to. The CJD Foundation helpline, on 1-800-659-1991, takes calls from families who have just heard the term.
What is happening in the brain?
FFI is one of the inherited prion diseases. Prion protein, which everyone makes, folds into the wrong shape and builds up, and in FFI the damage falls mainly on the thalamus. The thalamus manages the cycle of sleeping and waking, which is why sleep is affected so early and so severely.
It is very rare. At least 25 families are known worldwide, which makes it the rarest of the inherited prion diseases.
What causes it?
A change in PRNP, the gene carrying the instructions for prion protein. Almost all cases come from one particular change, written D178N, and whether it produces FFI or a form of genetic CJD depends on a second, common difference in the same gene at a place called codon 129.
It is inherited in an autosomal dominant pattern. One changed copy is enough, and a parent who carries it has a 50 percent chance of passing it to each child. There is also a very rare form that is not inherited at all, called sporadic fatal insomnia, which happens on its own.
Questions about your own family belong with a genetic counsellor, who comes before any test. Genetic counselling comes first explains why, and choosing not to be tested is a valid choice.
How does it usually begin?
Sleeplessness that keeps getting worse is the usual first sign, often with confusion or unsteadiness alongside it. Other common symptoms are anxiety, low mood, high blood pressure and heavy sweating, which happen because the nerves controlling automatic body functions are involved. Weight loss, memory problems and hallucinations may follow. Symptoms usually start in midlife, in the 30s, 40s or 50s.
Published reviews describe the illness as typically running longer than a year, which is somewhat longer than sporadic CJD. Nobody can say in advance how it will go for one person.
How is it diagnosed?
A gene test is what settles it. Doctors also use a sleep study, called polysomnography, which shows the disturbed pattern of sleep, and a brain PET scan, which often shows reduced activity in the thalamus.
Some of the tests used for other prion diseases behave differently here. The EEG pattern seen in sporadic CJD, the usual MRI changes and some spinal fluid markers are often absent in FFI, and the spinal fluid seeding test can be negative. A negative result on one of those tests does not rule FFI out. How prion disease is diagnosed goes through the tests one by one.
What care is there?
There is no treatment that stops the disease. Many of the symptoms can be eased, including poor sleep, agitation, distress and pain, and a palliative care team can be involved early rather than only at the end. What to expect covers the practical side of care at home and in hospital, and support groups lists people who talk with families every day.
Research is active, including studies in families who carry the gene change. Current trials keeps the list with eligibility as the sponsors state it.
Where next?
Fatal familial insomnia: more detail is the clinical version of this page, and FFI for researchers the scientific one. Genetic prion disease covers the inherited forms together, and CJD the commonest of them.
Nothing here describes a particular person. Questions about symptoms, test results or what a gene change means in your family belong with a neurologist and a genetic counsellor.