Gerstmann-Sträussler-Scheinker syndrome
Encyclopedia
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).
The exact incidence
of GSS is unknown but is estimated to be between 1 to 10 per 100 million.
Familial cases are associated with autosomal dominant inheritance.
s, a class of pathogenic proteins highly resistant to proteases.
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.
(difficulty speaking) and cerebellar ataxia
(unsteadiness) and then the progressive dementia
becomes more evident. Loss of memory can be the first symptom of GSS. 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.
Disease
A disease is an abnormal condition affecting the body of an organism. It is often construed to be a medical condition associated with specific symptoms and signs. It may be caused by external factors, such as infectious disease, or it may be caused by internal dysfunctions, such as autoimmune...
that affects patients from 20 to 60 years in age. This extremely rare disease is classified as a transmissible spongiform encephalopathy
Transmissible spongiform encephalopathy
Transmissible spongiform encephalopathies , also known as prion diseases, are a group of progressive conditions that affect the brain and nervous system of many animals, including humans. According to the most widespread hypothesis they are transmitted by prions, though some other data suggest an...
(TSE).
The exact incidence
Incidence (epidemiology)
Incidence is a measure of the risk of developing some new condition within a specified period of time. Although sometimes loosely expressed simply as the number of new cases during some time period, it is better expressed as a proportion or a rate with a denominator.Incidence proportion is the...
of GSS is unknown but is estimated to be between 1 to 10 per 100 million.
Familial cases are associated with autosomal dominant inheritance.
Causes
GSS is one of a small number of diseases which are caused by prionPrion
A prion is an infectious agent composed of protein in a misfolded form. This is in contrast to all other known infectious agents which must contain nucleic acids . The word prion, coined in 1982 by Stanley B. Prusiner, is a portmanteau derived from the words protein and infection...
s, a class of pathogenic proteins highly resistant to proteases.
A change in codon 102 from proline
Proline
Proline is an α-amino acid, one of the twenty DNA-encoded amino acids. Its codons are CCU, CCC, CCA, and CCG. It is not an essential amino acid, which means that the human body can synthesize it. It is unique among the 20 protein-forming amino acids in that the α-amino group is secondary...
to leucine
Leucine
Leucine is a branched-chain α-amino acid with the chemical formula HO2CCHCH2CH2. Leucine is classified as a hydrophobic amino acid due to its aliphatic isobutyl side chain. It is encoded by six codons and is a major component of the subunits in ferritin, astacin and other 'buffer' proteins...
on chromosome 20, has been found in the prion protein gene
Gene
A gene is a molecular unit of heredity of a living organism. It is a name given to some stretches of DNA and RNA that code for a type of protein or for an RNA chain that has a function in the organism. Living beings depend on genes, as they specify all proteins and functional RNA chains...
(PRNP
PRNP
Major prion protein also known as CD230 is a protein that in humans is encoded by the PRNP gene...
) of most affected individuals. Therefore, it appears this genetic
Genetics
Genetics , a discipline of biology, is the science of genes, heredity, and variation in living organisms....
change is usually required for the development of the disease.
Symptoms
Symptoms start with slowly developing dysarthriaDysarthria
Dysarthria is a motor speech disorder resulting from neurological injury of the motor component of the motor-speech system and is characterized by poor articulation of phonemes...
(difficulty speaking) and cerebellar ataxia
Ataxia
Ataxia is a neurological sign and symptom that consists of gross lack of coordination of muscle movements. Ataxia is a non-specific clinical manifestation implying dysfunction of the parts of the nervous system that coordinate movement, such as the cerebellum...
(unsteadiness) and then the progressive dementia
Dementia
Dementia is a serious loss of cognitive ability in a previously unimpaired person, beyond what might be expected from normal aging...
becomes more evident. Loss of memory can be the first symptom of GSS. 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
Prion
A prion is an infectious agent composed of protein in a misfolded form. This is in contrast to all other known infectious agents which must contain nucleic acids . The word prion, coined in 1982 by Stanley B. Prusiner, is a portmanteau derived from the words protein and infection...
protein.
Prognosis
There is no cure or treatment for GSS. It can, however, be identified through genetic testing. Symptoms may appear as early as 25 years of age, but usually in the late 50’s. Duration of illness can range from 3 months to 13 years, with an average duration of 5 or 6 years.External links
- 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