First report of the GSS syndrome
|Classification and external resources|
Gerstmann–Sträussler–Scheinker syndrome (GSS) is a very rare, usually familial, fatal neurodegenerative disease that affects patients from 20 to 60 years in age. Though exclusively heritable, this extremely rare disease is classified with the transmissible spongiform encephalopathies (TSE) due to the causative role played by PRNP, the human prion protein. The exact incidence of GSS is unknown but is estimated to be between 1 and 10 per 100 million.
Familial cases are associated with autosomal-dominant inheritance. Gerstmann-Straussler-Scheinker Disease (GSS) is an extremely rare neurogenetic brain disorder. It is always inherited and is found in only a few families all over the world (NINDS ¶ 1). The trait is an autosomal-dominant trait, caused by a gene mutation. It is also in a group of hereditary prion protein diseases or also known as TSEs. Many symptoms are associated with GSS, such as progressive ataxia, pyramidal signs, and even adult-onset dementia; they progress more as the disease progresses (Farlow, et al., Nov. 1989).
A change in codon 102 from proline to leucine on chromosome 20, has been found in the prion protein gene (PRNP) of most affected individuals. Therefore, it appears this genetic change is usually required for the development of the disease.
GSS is a disease that is very rare, making its history hard to track exactly where it descended from. Gerstmann-Straussler-Scheinker syndrome (GSS) were first described as neurodegenerative diseases in the 1920s (Elsevier Science, 2002). Gerstmann-Straussler-Scheinker (GSS) is called this because it was first reported in 1936 by Josef Gerstmann, Ernst Straussler and Ilya Scheinker. In 1989, the first mutation of the prion protein gene was identified in a GSS family (Elsevier Science, 2002). Prion diseases (transmissible spongiform encephalopathies) are rare degenerative diseases of the brain thought to be caused by a protein that converts to an abnormal form called a prion (Gambetti Pierluigi, 2013). GSS was later realized to have many different gene mutation types, with some showing different symptoms first or having other symptoms worse than others. Doctors in different parts of the world are uncovering more generations and families that have the mutation. It is hard to discover GSS for two main reasons: (1) the disease has been reported in only a few countries; and (2) the disease may be underreported due to its clinical similarity to other diseases (Ghetti B, et al., 2003). The Indiana Kindred is the largest, spanning over 8 generations, and includes over 3,000 people with 57 individuals known to be affected (B. Ghetti, et al., 1996).
Symptoms start with slowly developing dysarthria (difficulty speaking) and cerebellar ataxia (unsteadiness) and then the progressive dementia becomes more evident. Loss of memory can be the first symptom of GSS. Extrapyramidal and pyramidal symptoms and signs may occur and the disease may mimic spinocerebellar ataxias in the beginning stages. Myoclonus (spasmodic muscle contraction) is less frequently seen than in Creutzfeldt-Jakob disease. Many patients also exhibit nystagmus (involuntary movement of the eyes), visual disturbances, and even blindness or deafness. The neuropathological findings of GSS include widespread deposition of amyloid plaques composed of abnormally folded prion protein.
Treatment and testing
There is no cure for GSS, nor is there any known treatment to slow the progression of the disease. However, therapies and medication are aimed at treating or slowing down the effects of the symptoms. Their goal is to try to improve the patient's quality of life as much as possible. Despite there being no cure for GSS, it is possible to undergo testing for the presence of the underlying genetic mutation. Testing for GSS involves a blood and DNA examination in order to attempt to detect the mutated gene at certain codons. If the genetic mutation is present, the patient will eventually be afflicted by GSS, and, due to the genetic nature of the disease, the offspring of the patient are predisposed to a higher risk of inheriting the mutation.
There is no cure or treatment for GSS. It can, however, be identified through genetic testing. GSS is the slowest to progress among human prion diseases. Duration of illness can range from 3 months to 13 years, with an average duration of 5 or 6 years.
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- synd/2269 at Who Named It?
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- Gerstmann–Sträussler–Scheinker syndrome, MedicineNet.com
- UK CJD Surveillance Unit Monitors UK GSS cases and gives a comprehensive list of relevant links.
- Italian Spongiform Encephalopathies Association—AIEnP onlus
- A.I.En.P. Association Cause