Quantitative, functional MRI and neurophysiological markers in a case of Gerstmann-Sträussler-Scheinker syndrome

Gerstmann-Sträussler-Scheinker syndrome (GSS) is an inherited autosomal dominant prion disease, caused by a codon 102 proline to leucine substitution (P102L) in the prion protein gene (PRNP). We describe the case of a 40-year-old male, affected by a slowly progressive gait disturbance, leg weakness and cognitive impairment. Genomic DNA revealed a point mutation of PRNP at codon 102, resulting in P102L, and the diagnosis of GSS was confirmed. Somatosensory evoked potentials showed alterations of principal parameters, particularly in the right upper and lower limbs. Laser-evoked potentials were indicative of nociceptive system impairment, especially in the right upper and lower limbs. Conventional magnetic resonance imaging (MRI) revealed marked atrophy of the vermis and cerebellar hemispheres and mild atrophy of the middle cerebellar peduncles and brainstem, as confirmed by a brain volume automatic analysis. Resting-state functional MRI showed increased functional connectivity in the bilateral visual cortex, and decreased functional connectivity in the bilateral frontal pole and supramarginal and precentral gyrus. Albeit limited to a single case, this is the first study to assess structural and functional connectivity in GSS using a multimodal approach.

Reversible symptoms and clearance of mutant prion protein in an inducible model of a genetic prion disease in Drosophila melanogaster

Prion diseases are progressive disorders that affect the central nervous system leading to memory loss, personality changes, ataxia and neurodegeneration. In humans, these disorders include Creutzfeldt-Jakob disease, kuru and Gerstmann-Straüssler-Scheinker (GSS) syndrome, the latter being a dominantly inherited prion disease associated with missense mutations in the gene that codes for the prion protein. The exact mechanism by which mutant prion proteins affect the central nervous system and cause neurological disease is not well understood. We have generated an inducible model of GSS disease in Drosophila melanogaster by temporally expressing a misfolded form of the murine prion protein in cholinergic neurons. Flies accumulating this mutant protein develop motor abnormalities which are associated with electrophysiological defects in cholinergic neurons. We find that, upon blocking the expression of the mutant protein, both behavioral and electrophysiological defects can be reversed. This represents the first case of reversibility reported in a model of genetic prion disease. Additionally, we observe that endogenous mechanisms exist within Drosophila that are capable of clearing the accumulated prion protein.

A distinct phenotype of leg hyperreflexia in a Japanese family with Gerstmann-Sträussler-Scheinker syndrome (P102L)

Gerstmann-Sträussler-Scheinker Syndrome (GSS) is an inherited prion disease characterized by midlife onset and slowly progression of cerebellar ataxia and dementia. We report a distinct phenotype of leg hyperreflexia in a Japanese family with GSS. A 38-year-old woman noticed unsteady gait at 33 years of age. Afterwards, dysarthria and writing difficulty were appeared. Her family history revealed that her grandfather and her mother had a clinical history of unsteadiness and mental changes. At 1 year after clinical onset, neurological examination showed cerebellar ataxia and leg hyperreflexia. At 4 years after onset, she suddenly developed insomnia and nocturnal howling. Her mental status disclosed marked disorientation, anxiety and irritability. Muscle stretch reflexes were increased in four extremities with Babinski's signs. Remarkable dysarthria and cerebellar ataxia were presented. Brain diffusion weighted imaging showed extensive hyperintensity signal areas in the cerebral cortex. A point mutation of the prion protein gene (PRNP) at codon 102 resulting in the substitution of proline by leucine (P102L) was identified. PRNP polymorphism exhibited homozygous methionine at codon 129 and homozygous glutamate at codon 219. She had verbal perseveration, somnolence and myoclonus of lower limbs, leading to akinetic mutism at 4 months after neuropsychiatric events. Phenotypic hallmark of our patient indicates leg hyperreflexia from an early disease course. This neurological sign differs from the previously reported clinical expression of Japanese and foreign patients with GSS (P102L). Thus, physicians should pay more attention to phenotypic heterogeneity in this prion disease.

[Case of Gerstmann-Sträussler-Scheinker syndrome (GSS-P102L) mimicking variant Creurtzfeldt-Jakob disease in clinical manifestation and MRI findings]

We reported a 51-year-old woman with Gerstmann-Sträussler-Scheinker syndrome (GSS P102L) manifesting characteristic MRI findings. At the age of 45, She developed gait disturbance with muscle atrophy in the lower limbs and positive plantar flexor sign. Subsequently, sensory disturbance such as refractory pain in the lower limbs and ataxic gait were developed at the age of 49. Following these clinical symptoms, she finally demonstrated rapid progressive cognitive dysfunction. Just after presenting cognitive dysfunction, cranial MRI was performed. Cranial MRI with diffusion-weighted imaging and FLAIR imaging demonstrated abnormal high intensity lesions in the bilateral pulvinar, caudate nuclei and cerebral cortex. The degree of high signal at the pulvinar was less than those of the cortex and caudate nuclei. A proline-for-leucine substitution at codon 102 of the prion protein gene was demonstrated. These results allowed the diagnosis of GSS (P102L). This is a rare case of GSS (P102L) presenting with high intensity lesions in the bilateral pulvinar on MRI.

[Familial prion disease (GSS, familial CJD, FFI)]

We described clinically features of inherited prion disease (GSS, familial CJD and FFI). In addition, we found new useful findings of GSS patients for early diagnosis. Generally, clinicians believe that the main features of GSS (P102L) are cerebellar symptoms and dementia; however, our patients showed other features. Most showed mild gait disturbance, dysesthesia and hyporeflexia of the lower legs, proximal leg muscle weakness, and truncal ataxia during the early stage of the disease. Dementia was not a main symptom during the early stage. The key features for the early diagnosis of GSS102 are truncal ataxia, dysesthesia and hyporeflexia of the lower legs, and mild dysarthria. Normal cerebellar MRI and abnormal cerebral SPECT findings should be useful for early diagnosis of GSS (P102L).

The ε Isoform of 14-3-3 Protein Is a Component of the Prion Protein Amyloid Deposits of Gerstmann-Sträussler-Scheinker Disease

The 14-3-3 proteins are highly conserved, ubiquitous molecules involved in a variety of biologic events, such as transduction pathway modulation, cell cycle control, and apoptosis. Seven isoforms have been identified that are abundant in the brain, preferentially localized in neurons. Remarkable increases in 14-3-3 are seen in the cerebrospinal fluid of patients with Creutzfeldt-Jakob disease (CJD), and it has been found in pathologic inclusions of several neurodegenerative diseases. Moreover, the zeta isoform has been detected in prion protein (PrP) amyloid deposits of CJD patients. To further investigate the cerebral distribution of 14-3-3 in prion-related encephalopathies, we carried out an immunohistochemical and biochemical analysis of brain tissue from patients with Gerstmann-Sträussler-Scheinker disease (GSS) and sporadic, familial and acquired forms of CJD, using specific antibodies against the seven 14-3-3 isoforms. The study showed a strong immunoreactivity of PrP amyloid plaques of GSS patients for the 14-3-3 epsilon isoform, but not for the other isoforms. The epsilon isoform of 14-3-3 was not found in PrP deposits of CJD. These results indicate that the epsilon isoform of 14-3-3 is a component of PrP amyloid deposits of GSS and suggest that this is the sole 14-3-3 isoform specifically involved in the neuropathologic changes associated with this disorder.

Normal sleep-wake and circadian rhythms in a case of Gerstmann-Str�ussler-Sheinker (GSS) disease

A polysomnographic study showed normal sleep patterns and circadian rhythms in a patient with ataxic type GSS. Our results suggest that sleep and circadian rhythm changes in prion diseases are due to the involvement of specific brain areas.

Gerstmann-Sträussler-Scheinker disease. I. Human diseases

Gerstmann-Sträussler-Scheinker disease (GSS) is a slowly progressive hereditary autosomal dominant disease (OMIM: 137440) and the first human transmissible spongiform encephalopathy (TSE) in which a mutation in a gene encoding for prion protein (PrP) was discovered. Its true prevalence is difficult to estimate but figures within the range of 1-10/100,000,000 are quoted. GSS is defined as a neurodegenerative disease "in family with dominantly inherited progressive ataxia and/or dementia): encephalo(myelo)pathy with multi-centric PrP plaques". In this review, we summarise data on all the families with GSS. The hallmark of the GSS neuropathology is the multi-centric plaque but the pattern varies between families. In the second part of this review the experimental data using experimental models of GSS in transgenic mice are summarised as well as structural biology of mutated PrP in GSS.

Hereditary prion protein amyloidoses

Prion protein (PrP) amyloid accumulation is the pathologic hallmark of some inherited prion diseases such as Gerstmann-Sträussler-Scheinker disease (GSS) and PrP cerebral amyloid angiopathy (PrP-CAA). In GSS, parenchymal amyloidosis may coexist with spongiform degeneration or neurofibrillary tangles, whereas in PrP-CAA, vascular amyloid coexists with neurofibrillary tangles. In GSS, N-truncated and C-truncated proteinase K-resistant PrP isoforms are present in the brain.

Unhampered prion neuroinvasion despite impaired fast axonal transport in transgenic mice overexpressing four-repeat tau

Transmissible spongiform encephalopathies often are caused by peripheral uptake of infectious prions, and the peripheral nervous system is involved in prion spread to the brain. Although the cellular prion protein is subjected to fast axonal transport, the mechanism of intranerval transport of infectious prions is unclear. Here we administered prions intranervally to transgenic mice overexpressing the four-repeat human tau protein, which exhibit defective fast axonal transport. These mice showed unaltered neuroinvasion, suggesting that transport mechanisms distinct from fast axonal transport effect prion neuroinvasion along peripheral nerves. Surprisingly, scrapie-sick tau transgenic mice accumulated intraneuronal deposits of hyperphosphorylated tau protein. The coincidence of tau and prion pathology resembled Gerstmann-Sträussler-Scheinker syndrome. These findings identify tau pathology as a possible end stretch of prion-induced neurodegeneration.

Molecular advances in understanding inherited prion diseases

The prion diseases are neurodegenerative disorders that have attracted great interest because of the possible link between bovine spongiform encephalopathy (BSE) and variant Creutzfeldt-Jakob disease (CTD) in humans. Possible transmission of these diseases has been linked to a single protein termed the prion protein. This protein is an abnormal isoform of a normal synaptic glycoprotein. The majority of prion diseases does not appear to be caused by transmission of an infectious agent but occur spontaneously with no known cause. The strongest supporting evidence that the prion protein is the causative agent in prion disease comes from specific inheritable forms of prion disease which are linked to single point mutations in the prion protein gene. Paradoxically, these point mutations, although autosomal dominant with 100% penetrance do not lead to disease until late in life. Molecular techniques are now being used extensively to determine how these point-mutations alter the prion protein's normal structure and activity. This review deals with the latest insights into how inherited mutations in the prion protein gene lead to neurodegenerative disease.

A new PRNP mutation (G131V) associated with Gerstmann-Sträussler-Scheinker disease

BACKGROUND

Gerstmann-Sträussler-Scheinker disease is a rare form of prion disease.

OBJECTIVE

To determine the prion mutation in a 51-year-old man without a family history of neurologic disease who died from Gerstmann-Sträussler-Scheinker disease.

PATIENT AND METHODS

The patient was a 51-year-old man who died after a 9-year illness characterized by dementia and eventually ataxia. Neuropathologic studies were performed, the results of which revealed abundant prion protein-immunopositive amyloid plaques in the cerebellum without spongiform degeneration.

RESULTS

Genetic analysis of the prion protein gene showed a novel mutation at codon 131 that caused a valine-for-glycine substitution (G131V) and homozygosity at codon 129 (129M). Proteinase K-resistant prion protein was detected by Western blot analysis.

CONCLUSIONS

This is the first mutation described in the short, antiparallel beta-sheet domain of the prion protein. This report highlights the importance of genetic analysis of patients with atypical dementia even in the absence of a family history.

[A case of Gerstmann-Sträussler-Scheinker syndrome (GSS) with late onset--a haplotype analysis of Glu219Lys polymorphism in PrP gene]

We report a 74-year-old man with late onset Gerstmann-Sträussler-Scheinker syndrome (GSS). In this family, 3 out of 6 siblings and his father developed cerebellar ataxia and mental deterioration in their fifth decades. He complained of unsteady walking and tingling pain in the legs at the age of 70. Neurological examination revealed moderate truncal ataxia, mild limb ataxia, ataxic speech, sensory impairment, paresthesia and areflexia in the lower extremities. CSF examination showed elevated CSF and 14-3-3 proteins with a normal cell count. EEG and brain MRI demonstrated no abnormality. Somatosensory evoked potential (SEP) study showed delayed N13-N20 interpeak latencies in the upper extremities and delayed N20 at 12th thoracic spinous process, indicating dysfunction of the posterior roots or columns of the spinal cord including the dorsal horns and proximal peripheral nerve. Analysis of the prion protein gene demonstrated a Pro102Leu amino acid substitution, which is compatible with classical GSS. Haplotype analysis of the PrP gene identified a Glu219Lys polymorphism on another allele. Recently, it was confirmed that protein X, which accelerates the conversion of the normal type of PrP (PrPC) into a pathological type of PrP (PrPSc), binds to the 219th amino acid residue of PrP. Therefore, the 219Lys polymorphism theoretically inhibited formation of PrPSc and may thus have delayed the onset of the disease in this patient.

A synthetic peptide initiates Gerstmann-Sträussler-Scheinker (GSS) disease in transgenic mice

The molecular basis of the infectious, inherited and sporadic forms of prion diseases is best explained by a conformationally dimorphic protein that can exist in distinct normal and disease-causing isoforms. We identified a 55-residue peptide of a mutant prion protein that can be refolded into at least two distinct conformations. When inoculated intracerebrally into the appropriate transgenic mouse host, 20 of 20 mice receiving the beta-form of this peptide developed signs of central nervous system dysfunction at approximately 360 days, with neurohistologic changes that are pathognomonic of Gerstmann-Sträussler-Scheinker disease. By contrast, eight of eight mice receiving a non-beta-form of the peptide failed to develop any neuropathologic changes more than 600 days after the peptide injections. We conclude that a chemically synthesized peptide refolded into the appropriate conformation can accelerate or possibly initiate prion disease.

Novel PRNP sequence variant associated with familial encephalopathy

Human transmissible spongiform encephalopathies (TSEs) are a group of chronic progressive neurodegenerative disorders that may be hereditary, infectious, or sporadic. Hereditary TSEs are associated with mutations in the PRNP gene on chromosome 20p12-pter. We report on a family in which seven patients developed limb and truncal ataxia, dysarthria, myoclonic jerks, and cognitive decline. The age of onset in the 30s, 40s, or 50s, prolonged disease duration, cerebellar atrophy on imaging, and the presence of synchronic periodic discharges on electroencephalogram suggested a familial encephalopathy resembling Gerstmann-Sträussler-Scheinker disease. A novel H187R mutation has been identified in affected, but not in unaffected, family members or unrelated controls suggesting a pathogenic role for this mutation. Am. J. Med. Genet. (Neuropsychiatr. Genet.) 88:653-656, 1999. Published 1999 Wiley-Liss, Inc.

Gerstmann-Sträussler-Scheinker disease- the dilemma of molecular and clinical correlations

Gerstmann-Sträussler-Scheinker disease (GSSD) is a hereditary as well as transmissible human prion disease, restricted to families carrying point mutations of the PRPN gene on chromosome 20. To date 7 different causative mutations have been found. In this review the results of molecular biology with regard to the clinical course are discussed. As the findings of the disorder are very variable, the clinical picture and the neuropathology are extensively reported. An attempt has been made to define the disease, and filter out atypical non-GSSD cases. Finally, a comprehensive bibliography and tabulation of cases reported in the Western and Japanese literature are provided.

Involvement of the spinal posterior horn in Gerstmann-Sträussler-Scheinker disease (PrP P102L)

OBJECTIVE

The authors studied the pathomechanisms of the characteristics associated with Gerstmann-Sträussler-Scheinker disease (GSS).

BACKGROUND

GSS, associated with a missense mutation at codon 102 of the prion protein (PrP) gene (GSS102), is a hereditary disorder that presents with progressive ataxia and dementia, and is characterized by the loss of deep tendon reflexes and painful dysesthesias of the legs in its early stage.

METHODS

The authors conducted immunohistochemical studies of the spinal cord and peripheral nervous system in one of two patients from a Japanese family with GSS102 in comparison with patients with GSS105.

RESULTS

The authors found intense PrP immunoreactivities mainly in the posterior horn of the spinal cord, but not in the dorsal root ganglia or peripheral nerves. In addition to PrP amyloid plaques, synaptic-type, fine granular PrP deposits were distributed in the spinal posterior horns. In contrast to the GSS102 patient, the spinal cords of the GSS105 patients showed no granular PrP deposits.

CONCLUSIONS

The PrP abnormalities in synaptic structures of the spinal posterior horn may cause synaptic dysfunction that leads to loss of deep tendon reflexes and painful dysesthesias in patients with GSS102.

Different patterns of truncated prion protein fragments correlate with distinct phenotypes in P102L Gerstmann-Sträussler-Scheinker disease

The clinicopathological phenotype of the Gerstmann-Sträussler-Scheinker disease (GSS) variant linked to the codon 102 mutation in the prion protein (PrP) gene (GSS P102L) shows a high heterogeneity. This variability also is observed in subjects with the same prion protein gene PRNP haplotype and is independent from the duration of the disease. Immunoblot analysis of brain homogenates from GSS P102L patients showed two major protease-resistant PrP fragments (PrP-res) with molecular masses of approximately 21 and 8 kDa, respectively. The 21-kDa fragment, similar to the PrP-res type 1 described in Creutzfeldt-Jakob disease, was found in five of the seven subjects and correlated with the presence of spongiform degeneration and "synaptic" pattern of PrP deposition whereas the 8-kDa fragment, similar to those described in other variants of GSS, was found in all subjects in brain regions showing PrP-positive multicentric amyloid deposits. These data further indicate that the neuropathology of prion diseases largely depends on the type of PrP-res fragment that forms in vivo. Because the formation of PrP-res fragments of 7-8 kDa with ragged N and C termini is not a feature of Creutzfeldt-Jakob disease or fatal familial insomnia but appears to be shared by most GSS subtypes, it may represent a molecular marker for this disorder.

[Gerstmann-Straüssler-Scheinker syndrome]

The Gerstmann-Sträussler-Scheinker syndrome, is a disease transmitted by autosomal dominant inheritance characterized by nonsense mutations of the prion protein associated with specific neuropathological lesions-multicentric amyloid plaques labelled by antibodies directed against the prion protein. This restrictive definition justifies retaining the name of Gerstmann-Sträussler-Scheinder syndrome and excludes observations of hereditary prion diseases without multicentric amyloid plaques and sporadic forms with multicentric plaques. The main feature of these different observations is their polymorphous clinical presentation which varies not only between families with the same mutation but also with a given family. The underlying mechanisms of the phenotypic polymorphism remain uncertain.

A Japanese family with a variant of Gerstmann-Sträussler-Scheinker disease

OBJECTIVE

A new variant of Gerstmann-Sträussler-Scheinker disease (GSS) was reported, which had a substitution of glutamate to lysine at codon 219 (E219K) in addition to a P102L mutation on the same allele of the PrP gene. However, clinical features were not detailed and pathological studies were not done. Unusual clinical, neuroradiological, and pathological findings are reported for these patients.

METHODS AND RESULTS

Clinical presentations of the patients in the same family were variable; progressive dementia with minimal ataxia in some patients but ataxia without dementia in others. PET studies with 18F-2-fluoro-2-deoxyglucose (FDG) disclosed a relative decrease of FDG uptake in bilateral temporoparietal cortices of a patient with dementia, but in the cerebellar cortices in a patient with ataxia. At necropsy, a patient with dementia had multicentric and diffuse plaques stained with PrP antiserum, but not with haematoxylin and eosin or Congo red, in the cerebral and cerebellar cortices.

CONCLUSION

Neurological and neuropathological features in the patients were atypical of the classic form of GSS with P102L mutation. The absence of Congo red staining prion protein plaques is probably attributable to E219K polymorphism on the same allele of the PrP gene.

[Gerstmann-Straussler syndrome clinical and neuromorphofunctional diagnosis: a case report]

The Syndrome of Gerstmann-Straussler is a constellation of typical symptoms that affects the parietotemporal crossroad and also involves the contiguous parts of the occipital lobe of the dominant hemisphere. Is a family ailment that starts with an espinocerebellar ataxy followed by dementia. Diagnosis options such as EEG, TC, RM and brain SPECT-99mTc-HMPAO have been carried out in an adult with Gerstmann Syndrome.

RESULTS

The brain SPECT disclosed a disminution of the flow at the parietotemporooccipital areas of both hemispheres. The results revealed a clinical and a neuromorphofunctional correlation.

CONCLUSION

Brain SPECT is a complementary test to the structural neuroradiological examinations, such as TC and RM, that occasionally is useful not only to clarify but also to widen the information that these offer.

Abnormal eye movements in Gerstmann-Sträussler-Scheinker disease

Gerstmann-Sträussler-Scheinker disease is a familial disorder of progressive ataxia and dementia in adulthood with extrapyramidal signs in some families. Neuro-ophthalmic examinations and eye movement recordings were performed in members of a large Indiana kindred. Five affected members and 11 members at risk were studied. Eye movements were recorded with videotape, electro-oculography, and/or magnetic scleral search coil. All affected members had abnormal eye movements characteristic of extrapyramidal diseases and cerebellar disorders. Nine members at risk had normal eye movements, but two others had slightly abnormal eye movements. Neuro-ophthalmic examination and eye movement recordings might be helpful in detecting early signs of Gerstmann-Sträussler-Scheinker disease in persons at risk.

Immunochemical, molecular genetic, and transmission studies on a case of Gerstmann-Sträussler-Scheinker syndrome

Using immunostaining with anti-prion protein (PrP) antiserum, we detected numerous kuru plaques in the brain of a 24-year-old man with Gerstmann-Sträussler-Scheinker syndrome. Immunoreactivity on Western blotting of the protease-resistant PrP fraction from the frozen brain was weak. PrP gene analysis showed substitution of alanine to valine in codon 117 but no substitution in codon 102. As the experimental transmission of the disease to mice was negative, a pathogen of a relatively low infectivity may cause the disease in predisposed family members.