Gerstmann-Straussler-Scheinker Disease (GSS) is an extremely rare neurodegenerative brain disorder. It is almost always inherited (autosomal dominant) and is found in only a few families around the world. Onset of the disease usually occurs between the ages of 35 and 50.

GSS is caused by mutations in the PRNP gene. PRNP encodes a protein called prion protein. Although the exact function of this protein is unknown, it appears to play an important role in the human brain and other tissues throughout the body. In people with GSS, mutations in the PRNP gene typically result in the production of an abnormally shaped prion protein. The abnormal protein builds up in the brain, forming clumps that damage or destroy neurons (nerve cells). This loss of brain cells leads to the signs and symptoms of GSS.

Diagnostic testing: The diagnosis of GSS is based on a combination of the following:

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  Observation of the characteristic physical signs and symptoms;

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  Nervous system findings including multiple amyloid plaques (clumps which form in the brain and cause the death of nerve cells and the progressive symptoms of the disease);

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  A family history consistent with autosomal dominant inheritance; and

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  Genetic test showing a disease-causing mutation of the PRNP gene (establishes and confirms the diagnosis).

Physical findings: The physical findings of GSS may include:

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  Progressive ataxia, including clumsiness, unsteadiness, and difficulty walking;

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  Cognitive dysfunction leading to bradyphrenia (slowness of thought processing) and dementia of different degrees;

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  Dysarthria (slurred speech);

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  Nystagmus (abnormal eye movements);

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  Spasticity (rigid muscle tone);

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  Visual disturbances, sometimes leading to blindness;

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  Deafness; and

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  Parkinsonian features.

ICD-9: 046.71

ICD-10: A81.8; A81.82

The signs and symptoms of GSS disease generally develop between the ages of 35 and 50 years. 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.

The treatment of GSS is based on the signs and symptoms present in each person. There is currently no cure for the condition and no known treatments to slow its progression.

Suggested MER for Evaluation:

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  Clinical history and examination that describes the diagnostic features of the impairment;

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  Full neurological examination with emphasis on motor function and coordination, gait and balance, eye movements and gaze, and cognitive function; and

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  Genetic testing for mutations of the PRNP gene.

Suggested Listings for Evaluation:

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