Gerstmann-Straussler Disease

A number sign (#) is used with this entry because of evidence that Gerstmann-Straussler disease (GSD) and a form of cerebral amyloid angiopathy are caused by heterozygous mutation in the prion protein gene (PRNP; 176640) on chromosome 20p13.

Creutzfeldt-Jakob disease (CJD; 123400) and familial fatal insomnia (FFI; 600072) are 2 other allelic inherited prion diseases caused by mutation in the PRNP gene.

Description

Gerstmann-Straussler disease is a rare inherited prion disease characterized by adult onset of memory loss, dementia, ataxia, and pathologic deposition of amyloid-like plaques in the brain (Gerstmann et al., 1936). Gerstmann-Straussler disease typically presents with progressive limb and truncal ataxia, dysarthria, and cognitive decline in the thirties and forties, and the average disease duration is 7 years. GSD can be distinguished from CJD by earlier age at onset, longer disease duration, and prominent cerebellar ataxia (Masters et al., 1981).

On the basis of clinical and pathologic criteria, Hsiao et al. (1989) suggested that Gerstmann-Straussler syndrome could be classified into 3 forms: an 'ataxic' form, a 'dementing' form, and a dementing form that is accompanied by pathologic quantities of neurofibrillary tangles (NFTs). However, these distinctions may only underscore the phenotypic variability in presentation and progression of the disease (Panegyres et al., 2001).

PRNP-related amyloid angiopathy is usually not a feature of CJD, GSD, or FFI. However, PRNP-immunoreactive amyloid deposits within the walls of cerebral vessels have been observed in patients with truncating mutations in the PRNP gene. Data suggest that C-terminal-truncated PRNP proteins lacking the glycosylphosphatidylinositol (GPI) anchor required to attach the protein to the plasma membrane may readily form amyloid fibrils that result in cerebrovascular amyloid deposition (summary by Revesz et al., 2009).

Clinical Features

Seitelberger (1962) described a kindred with a unique neurologic disorder traced through 5 generations. Plaque-like deposits were found in the cerebral cortex, basal ganglia, and (most extremely) all layers of the cerebellum. Clinically and pathologically the disorder most closely resembled kuru, although the authors noted some differences in the plaque distribution. Kretzschmar et al. (1991) noted that the family reported by Seitelberger (1962) was the same family originally reported by Gerstmann et al. (1936).

Peiffer (1982) described a family of sheepbreeders in which a father and 2 sons had GSD. All 3 also had congenital hip dysplasia, as did at least 3 other members of the kindred, all females. The main clinical features included ataxia, dysarthria, and personality changes. Peiffer (1982) noted that GSD was characterized neuropathologically by large plaques distributed throughout the cerebral cortex, basal ganglia, and white matter.

Hudson et al. (1983) reported a family in which Gerstmann-Straussler disease occurred in 3 members of 2 generations. The clinical picture included visual loss in 1 patient and sensory loss in another patient. Dementia only occurred late in the illness in 2 patients. Neuropathologic examination showed multicentric amyloid plaques in the cerebral and cerebellar cortices, basal ganglia, and white matter, as well as degeneration of the corticospinal tract, spinocerebellar tract, and dorsal columns. Spongiform changes were limited to the superficial cerebral cortex. Vinters et al. (1986) presented the postmortem neuropathologic findings in 1 of the patients reported by Hudson et al. (1983). The disorder had lasted 8 years. There were severe spongy changes in the neocortex, extensive and often large amyloid deposits throughout the cerebral hemispheres and cerebellum, and severe astrocytic gliosis throughout all areas of gray and white matter within the brain. The degree of cortical spongy change was much greater than that in relatives who died with a similar clinical history.

Farlow et al. (1989) reported a large kindred from Indiana with Gerstmann-Straussler disease inherited in an autosomal dominant pattern. Sixty-four patients showed progressive ataxia, dementia, and parkinsonism with onset in the late thirties to early sixties. Early features included impaired smooth pursuit eye movements, impaired short-term memory, and clumsiness of the hands. In late stages of the disease, there was dementia, psychosis, and/or severe depression with weight loss. Death occurred 6 months to 2 years after onset. Farlow et al. (1989) noted that the neuropathologic findings in affected members of the Indiana kindred included widespread amyloid plaques in the cerebrum and cerebellum as well as widespread Alzheimer (104300)-like neurofibrillary tangles composed of paired helical filaments in the cerebral cortex and subcortical nuclei. The amyloid core of plaques was immunolabeled with antibodies raised to PrP, but not with antibodies raised to beta-amyloid (APP; 104760). Spongiform changes were mild. The disease in the Indiana kindred was traced to the year 1792 (Farlow et al., 1989; Ghetti et al., 1989). In each of the generations since 1792, affected members had been identified by either history or clinical examination.

Yamada et al. (1999) found intense deposition of prion protein in the posterior horn of the spinal cord but not in the dorsal root ganglia or peripheral nerves in an autopsy of a 38-year-old woman with GSD confirmed by mutation in the PRNP gene (P102L; 176640.0002). The findings seemed to account for the painful dysesthesias and arreflexia seen in this variant of the disorder.

Panegyres et al. (2001) reported a man with GSD confirmed by mutation in the PRNP gene (176640.0021). He had no family history of neurologic disease. At disease onset in his forties, he developed impaired short-term memory function, reduced learning capacity, and personality changes, including emotional immaturity, anxiety, and increasing anger. Neurologic examination showed apraxia, tremor, rigidity, and hyperreflexia, but no ataxia. Eventually he developed ataxia and his dementia progressed. He died at age 51, 9 years after symptom onset. Neuropathologic examination showed mild cerebral and cerebellar atrophy. There were numerous congophilic amyloid plaques throughout the brain that were immunoreactive to PrP. There was no spongiform degeneration; occasional neurofibrillary tangles were seen.

Arata et al. (2006) reported detailed clinical features of 11 individuals from 9 families with GSS, all of whom had the common P102L mutation of the PRNP gene. Age at onset ranged from 38 to 70 years, with an average of 60.2 years. Nine patients presented with gait disturbance, 1 with dysarthria, and 1 with dysesthesia of the lower limbs. Common features of the early stage of disease were unsteady gait, truncal ataxia, painful dysesthesias of the lower limbs, weakness of the proximal lower limbs, loss of deep tendon reflexes, and mild dysarthria. Ten of the 11 patients were initially evaluated by orthopedic surgeons on the suspicion of lumbar spine disease, none of whom diagnosed GSS. Only 1 patient had clear dementia on initial examination. Brain MRIs were normal during the initial stages and no patients had cerebellar changes. However, all patients developed cortical and diffuse brain atrophy with disease progression and onset of dementia. Brain SPECT studies of 5 patients showed hypoperfusion of the occipital lobes and patchy decreased blood flow in the cerebrum, with normal flow in the cerebellum. Arata et al. (2006) concluded that the sites of pathology in this group of patients were in the cerebrum and spinal cord, including the posterior horn and spinocerebellar tracts, instead of the cerebellum proper.

Yamamoto et al. (2007) reported a 72-year-old man with GSS who presented with a 1-year history of progressive limb weakness, aphasia, and apathy. Diffusion-weighted brain MRI at the initial examination showed hyperintense signal changes in the frontal, temporal, occipital, and parietal cortical gyri of both hemispheres, although CT scan showed no abnormalities. His condition deteriorated over the next 8 months, resulting in mutism, akinesia, and spastic tetraplegia. CT scans performed at 2 and 8 months after the initial examination showed remarkable progression of cortical atrophy in the bilateral frontotemporal lobes and hypodense lesions in frontal subcortical areas.

Rowe et al. (2007) reported a 62-year-old woman with a phenotype most consistent with Gerstmann-Straussler disease. The phenotype was somewhat unusual in that she exhibited supranuclear gaze palsy early in the disease course and had absence of myoclonus, lack of 14-3-3 proteins (see 113508) in the CSF, and no significant EEG or MRI findings. The patient later developed more typical features of the disorder with rapid progression to death 4 months after presentation. Postmortem examination showed typical diffuse spongiform encephalopathy with amyloid-like plaques restricted to the cerebellum. Genetic analysis identified a heterozygous mutation in the PRNP gene (176640.0026).

PRNP-Related Amyloid Angiopathy

Ghetti et al. (1996) reported a Japanese woman who developed progressive dementia at age 38 resulting in death at age 59 years and associated with PrP-immunoreactive cerebral amyloid angiopathy. Family history was not contributory. Neuropathologic examination showed severe cortical atrophy with amyloid deposits in the parenchymal and leptomeningeal blood vessels and in the perivascular neuropil, as well as marked tau (MAPT; 157140)-immunoreactive neurofibrillary tangles, similar to those observed in Alzheimer disease. Amyloid was also present in the surrounding parenchyma. Amyloid was immunoreactive to PrP, and immunoblot analysis detected mainly a 7.5-kD peptide that was truncated at the N- and C-termini, with immunoreactivity between residues 90 and 147. Amyloid-laden vessels were also labeled by antibodies against the C terminus, suggesting that PrP from the normal allele was also involved in the pathologic process. Genetic analysis revealed a heterozygous truncating mutation in the PRNP gene (Y145X; 176640.0031). Ghetti et al. (1996) noted that abnormal PRNP truncation at a similar site (between residues 144 and 150) occurs in GSS variants in which the amyloid protein has been analyzed, suggesting that this truncated PrP peptide is important for amyloid formation.

Jansen et al. (2010) reported a 57-year-old Dutch woman with PRNP-related cerebral amyloid angiopathy. She presented at age 55 years with a 12-month history of increasing cognitive impairment, forgetfulness, and decreased concentration associated with hallucinations. She also had aphasia, but no extrapyramidal signs, ataxia, or myoclonic jerks. EEG showed generalized slowing with a typical pattern of periodic synchronous wave complexes. The disorder progressed, and she developed parkinsonism as a result of neuroleptic treatment, mutism, akinesia, and myoclonic jerks. She died 27 months after onset. Neuropathologic examination showed severe PRNP-reactive amyloid angiopathy and parenchymal plaques; neurofibrillary tangles were not present, but there were focal tau accumulations. Her mother was diagnosed with probable CJD on the basis of comparable symptoms and signs. Genetic analysis identified a heterozygous truncating mutation in the PRNP gene (Y226X; 176640.0033). The patient was heterozygous for M129V (176640.0005). An unrelated patient had a similar truncating PRNP mutation, Q227X (176640.0034), associated with amyloid plaques and extensive neurofibrillary tangles, but not amyloid angiopathy. Both Y226X and Q227X result in C-terminally truncated proteins lack the GPI anchor and thus cannot localize to the plasma membrane, suggesting that absence of this anchor predisposes to amyloid formation.

Jayadev et al. (2011) reported a woman with onset of progressive memory impairment and depression beginning at age 39 years and resulting in death at age 47. The patient was initially diagnosed with Alzheimer disease. Neuropathologic examination showed frontotemporal atrophy, severe tau-immunoreactive neurofibrillary tangles, and amyloid plaques that were immunoreactive to PRNP. The prion deposits were immunopositive to residues 90-102, but not to 220-231, consistent with C-terminal truncation. Western blot analysis showed a smear of proteinase K-resistant PrP, the most prominent of which was 11 kD. PrP-immunoreactive amyloid angiopathy was observed. There was also immunoreactivity to alpha-synuclein (SNCA; 163890), in the form of Lewy bodies and Lewy neurites. Spongiform changes were not observed. The patient's deceased mother had a history of a similar disorder with later onset and accompanied by severe chronic diarrhea. She was diagnosed with Alzheimer disease, but reexamination of her pathology showed the same abnormalities as observed in her daughter. Genetic analysis identified a heterozygous mutation in the PRNP gene (Q160X; 176640.0032) in the proband and her mother. The proband was heterozygous for M129V, whereas her mother was homozygous for M129. Jayadev et al. (2011) postulated a link between truncating PRNP mutations and the development of a disorder with a relatively prolonged clinical course and features similar to AD.

Pathogenesis

Masters et al. (1981) reported that inoculation of brain tissue from 3 patients with GSD resulted in spongiform encephalopathy in nonhuman primates, supporting a relation to Creutzfeldt-Jakob disease. One of these patients was a member of the family reported by Adam et al. (1982) as an instance of familial cerebral amyloidosis.

Prusiner (1987) reviewed the possible role of prions in GSD as well as in other diseases such as CJD and kuru. Brown et al. (1993) examined the question of whether 'prion dementia' should replace 'spongiform encephalopathy' to accommodate the existence of atypical forms of these 'prion protein' cerebral amyloidoses that may not show spongiform changes in the brain. They tested for the presence of PrP in brain tissue extracts from 46 cases, including 13 familial cases, of nonspongiform dementias with a variety of associated neurologic signs. None of the cases transmitted disease to primates, and none had PrP detectable by Western immunoblots. Brown et al. (1993) concluded that the clinicopathologic limits of prion dementias are, except for a small number of previously reported familial cases, essentially those of spongiform encephalopathy.

Molecular Genetics

In affected members of 2 unrelated families with autosomal dominant inheritance of Gerstmann-Straussler disease, Hsiao et al. (1989) identified a heterozygous mutation in the PRNP gene (P102L; 176640.0002).

In a 36-year-old woman who belonged to the original family reported by Gerstmann et al. (1936) and Seitelberger (1962), Kretzschmar et al. (1991) identified a heterozygous P102L mutation in the PRNP gene.

In affected members of a large Indiana kindred with Gerstmann-Straussler disease reported by Ghetti et al. (1989), Hsiao et al. (1992) identified a mutation in the PRNP gene (176640.0011). Dlouhy et al. (1992) showed absolute linkage of the PRNP mutation to the clinical phenotype in the Indiana kindred. Their studies suggested that patients who were heterozygous for the PRNP met/val129 (176640.0005) polymorphism had a later age of onset of the disease than individuals who were either met129 or val129 homozygotes.

In a patient with GSD, Peoc'h et al. (2012) identified a heterozygous mutation in the PRNP gene (E211D; 176640.0029). The patient was homozygous for val129 (176640.0005). Neuropathologic studies showed typical features of GSS, including multicentric amyloid PrP-immunoreactive plaques, spongiform changes, mild gliosis, and neurofibrillary tangles. Proteinase K-resistant prion protein was found, and immunochemical studies showed accumulation of a C-terminal-truncated PrP fragment (roughly covering residues 80 to 150). Biophysical studies showed that the mutant protein had an increased tendency to aggregate, with a different effect on the PrP structural dynamics compared to the E211Q mutation (176640.0030), which was found in a patient with CJD.

PRNP-Related Amyloid Angiopathy

In a Japanese woman with PrP-immunoreactive cerebral amyloid angiopathy, Ghetti et al. (1996) identified a heterozygous truncating mutation in the PRNP gene (Y145X; 176640.0031). Ghetti et al. (1996) noted that abnormal PRNP truncation at a similar site (between residues 144 and 150) occurs in GSS variants in which the amyloid protein has been analyzed, suggesting that this truncated PrP peptide is important for amyloid formation.

In a patient with PRNP-related cerebral amyloid angiopathy, Revesz et al. (2009) reported a tyr163-to-ter (Y163X) substitution in the PRNP gene. Clinical data was not provided, but neuropathologic studies showed vascular and parenchymal PRNP-immunoreactive amyloid deposition and extensive neurofibrillary tangle pathology.

Jansen et al. (2010) identified a heterozygous truncating mutation in the PRNP gene (Y226X; 176640.0033) in a 57-year-old Dutch woman with PRNP-related cerebral amyloid angiopathy.

Animal Model

Telling et al. (1996) showed that the presence of wildtype PRNP genes, the level of PRNP transgene expression, and the sequence of the transgene can profoundly modify experimental prion disease in a transgenic mouse model with a murine P101L mutation in the Prnp gene, which is homologous to the human P102L mutation. They produced a homozygous animal for the mutant transgene array which caused spontaneous disease in a consistently shorter period of time than in the hemizygous animal. The authors concluded that the murine P101L mutation is required for CNS degeneration, that the clinical and neuropathic phenotypes of transgenic mice can be dramatically altered by ablation of the wildtype Prnp gene, and that this mouse model recapitulated virtually all features of human GSD.

Choi et al. (2010) established a Drosophila model of GSD by expressing mouse prion protein (PrP) with a leucine substitution at residue 101 (MoPrP(P101L)). Flies expressing MoPrP(P101L), but not wildtype MoPrP (MoPrP(3F4)), showed severe defects in climbing ability and early death. Expressed MoPrP(P101L) in Drosophila was differentially glycosylated, localized at the synaptic terminals, and mainly present as deposits in adult brains. Behavioral defects and early death of MoPrP(P101L) flies were not due to caspase-3 (CASP3; 600636)-dependent programmed cell death signaling. In addition, type 1 glutamatergic synaptic boutons in larval neuromuscular junctions of MoPrP(P101L) flies showed significantly increased numbers of satellite synaptic boutons. The amount of bruchpilot and discs large (DLG1; 601014) in MoPrP(P101L) flies was significantly reduced. Brains from scrapie-infected mice showed significantly decreased ELKS (ERC1; 607127), an active zone matrix marker, compared with control mice. The authors proposed that altered active zone structures at the molecular level may be involved in the pathogenesis of GSD in Drosophila and scrapie-infected mice.