Genetic

Familial Creutzfeldt-Jakob disease (fCJD)

Inherited mutations in the prion protein gene (PRNP) cause the familial form of prion disease. This prion gene provides instructions to your cells regarding how to make the prion protein. In fCJD, the mutations in this gene cause the cells to produce an abnormal form of the prion protein instead of the normal form. In most cases, the patient with fCJD inherits the altered gene from one affected parent. In some people, a new mutation in the gene causes fCJD. Although such people most likely do not have an affected parent, they can pass the genetic change to their children. The symptoms depend on type of mutation, but they often look like classic CJD: balance and coordination problems, memory loss and impaired thinking. Typically these symptoms appear earlier in fCJD than in sCJD. The duration of the illness is usually longer than in the sporadic form. The genetically inherited subtype accounts for about 15% of CJD cases.

Gerstmann-Sträussler-Scheinker syndrome (GSS)

Gerstmann-Straussler-Scheinker disease (GSS) is an extremely rare, neurodegenerative brain disorder. It is almost always inherited and is found in only a few families around the world. Onset of the disease usually occurs between the ages of 35 and 55. In the early stages, patients may experience varying levels of ataxia (lack of muscle coordination), including clumsiness, unsteadiness, and difficulty walking. As the disease progresses, the ataxia becomes more pronounced and most patients develop dementia. Other symptoms may include dysarthria (slurring of speech), nystagmus (involuntary movements of the eyes), spasticity (rigid muscle tone), and visual disturbances, sometimes leading to blindness. Deafness also can occur. In some families, parkinsonian features are present. GSS belongs to a family of human and animal diseases known as the transmissible spongiform encephalopathies (TSEs). Other TSEs include Creutzfeldt-Jakob disease, kuru, and fatal familial insomnia. Gerstmann-Sträussler-Scheinker syndrome (GSS) is a very rare, usually familial, fatal neurodegenerative disease that affects patients from 20 to 60 years in age. This extremely rare disease is classified as a transmissible spongiform encephalopathy (TSE). A rare familial form of progressive dementia inherited in an autosomal dominant manner due to a mutant prion gene on chromosome 20pter-p12.

Fatal Familial Insomnia (FFI)

Fatal familial insomnia (FFI) is a very rare autosomal dominant inherited disease of the brain. The dominant gene responsible has been found in just 28 families worldwide; if only one parent has the gene, the offspring have a 50% chance of inheriting it and developing the disease. The disease's genesis and the patient's progression into complete sleeplessness is untreatable, and ultimately fatal. There are four stages of the disease before an individual's life ends. The first stage is progressive insomnia, the trade mark of fatal familial insomnia. The first stage develops over approximately four months and includes a collection of psychiatric problems such as panic attacks and bizarre phobias. The second stage includes hallucinations, panic, agitation and sweating and lasts about five months. The third stage lasts about three months and is total insomnia with weight loss. The individual at this point looks much older and may experience incontinence. The fourth stage is around six months long and is recognized as dementia, total insomnia and sudden death after becoming mute.

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