Fatal familial insomnia: what kind of disease it is and how it manifests

Fatal familial insomnia is a rare case in which a person stops sleeping and the disease proves fatal. Below: what this disease is, how it is transmitted, and how it differs from ordinary sleep disorders.

Fatal familial insomnia: what kind of disease it is

Fatal insomnia is an extremely rare prion neurodegenerative disease that is currently incurable. Its main symptom is the inability to sleep: the sleep mechanism itself is destroyed. In the vast majority of cases the disease is inherited, but there is also an even rarer sporadic form, in which it arises on its own, without a clear cause.

Prion diseases affect the nervous system and over time lead to death. This group is very rare: approximately one case per million people per year worldwide.

Why the disease is called familial: heredity and prions

From 10 to 15 percent of all cases of prion diseases are caused by mutations in the PRNP gene. Such forms occur in families, which is why they are called familial. The PRNP gene is located on chromosome 20: in fatal insomnia, at codon 178, the normal aspartic acid is replaced by asparagine, the shape of the protein molecule changes, and an ordinary protein turns into a disease-causing prion.

The abnormal protein attaches to the normal one and converts it into the same kind, and accumulates in the brain in clumps that destroy neurons. In this disease, amyloid plaques form in the thalamus, the part of the brain responsible for sleep.

Inheritance is autosomal dominant: one altered copy of the gene is enough. If one of the parents is affected, the probability for the child is 50 percent; if neither parent was affected, the children will be healthy. Sporadic, acquired, and iatrogenic forms of prion diseases are not inherited.

How fatal insomnia manifests

The disease begins at the age of 13 to 60 years, most often at 50–52 years, and lasts from 7 to 36 months. Four stages have been described.

• Insomnia increases, panic attacks and phobias appear — on average about four months.
• Panic attacks become a serious problem, and hallucinations are added — about five months.
• Complete inability to sleep along with rapid weight loss — about three months.
• The person stops speaking and does not react to surroundings — on average six months, after which death occurs.

Other symptoms include profuse sweating, constricted pupils, neck rigidity, increased blood pressure and heart rate, and constipation; in women, sudden menopause is possible, and in men, impotence. As the disease progresses, the person becomes stuck in a state of hypnagogia — the pre-sleep uncertainty that healthy people experience before falling asleep.

How it differs from ordinary insomnia

The main difference is in the mechanism: in fatal insomnia it is not sleep that is disturbed but the sleep mechanism itself, so sleeping pills, as a rule, do not work fully. In addition, the course of the disease has been described fairly precisely: from 7 to 36 months and four stages, from increasing insomnia to loss of speech and reaction to surroundings.

Another difference is the family history: in sporadic forms of prion diseases there is no heredity and no mutations in the PRNP gene are found.

How the disease is diagnosed and what risks it carries

Diagnosis is handled by specialists; the presence of a mutation in the PRNP gene relates to inherited forms. The disease is incurable, and care is aimed at relieving symptoms and maintaining comfort — for anxiety, depression, or pain; some people need care and help with nutrition.

The risks are associated with the rapid progression of impairments: rapid weight loss, loss of speech and the ability to react. In Creutzfeldt–Jakob disease, a related prion condition, most people die within a year after symptoms appear, often from infection due to immobility.

When sleep disturbances require seeing a doctor

Poor sleep is a common story, and in most cases it is not related to prion diseases. People see a doctor for persistent sleep disturbances, especially if close relatives have had a prion disease.

Fatal insomnia by itself is not a reason to call an ambulance. 103 or 112 — if, against the background of severe sleep disturbances, signs of stroke or heart attack appear, or the condition sharply worsens and threatens life.

This material is for reference and does not replace a doctor's consultation: the decision on examinations is made by a specialist.

This content is for reference and does not replace a doctor's consultation. Medical disclaimer