Gerstmann-Straussler-Scheinker disease (GSS) is an extremely rare, neurodegenerative brain disorder.

Onset of the disease usually occurs between the ages of 35 and 55. The incidence of GSS is estimated to be between 1 to 10 per 100 million.

GSS is almost always inherited and is found in only a few families around the world. Familial cases are associated with autosomal dominant inheritance.

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.

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
• Visual disturbances, sometimes leading to blindness
• Deafness
• Parkinsonian features (in some families)

GSS is a slowly progressive condition usually lasting from 2 to 10 years. The disease ultimately causes severe disability and finally death, often after the patient goes into a coma or has a secondary infection such as aspiration pneumonia due to an impaired ability to swallow.

There is no cure for GSS, nor are there any known treatments to slow progression of the disease. Current therapies are aimed at alleviating symptoms and making the patient as comfortable as possible.