Multiparametric Analysis Combining DSC-MR Perfusion and [18F]FET-PET is Superior to a Single Parameter Approach for Differentiation of Progressive Glioma from Radiation Necrosis

PURPOSE

Perfusion-weighted (PWI) magnetic resonance imaging (MRI) and O‑(2-[18F]fluoroethyl-)-l-tyrosine ([18F]FET) positron emission tomography (PET) are both useful for discrimination of progressive disease (PD) from radiation necrosis (RN) in patients with gliomas. Previous literature showed that the combined use of FET-PET and MRI-PWI is advantageous; hhowever the increased diagnostic performances were only modest compared to the use of a single modality. Hence, the goal of this study was to further explore the benefit of combining MRI-PWI and [18F]FET-PET for differentiation of PD from RN. Secondarily, we evaluated the usefulness of cerebral blood flow (CBF), mean transit time (MTT) and time to peak (TTP) as previous studies mainly examined cerebral blood volume (CBV).

METHODS

In this single center study, we retrospectively identified patients with WHO grades II-IV gliomas with suspected tumor recurrence, presenting with ambiguous findings on structural MRI. For differentiation of PD from RN we used both MRI-PWI and [18F]FET-PET. Dynamic susceptibility contrast MRI-PWI provided normalized parameters derived from perfusion maps (r(relative)CBV, rCBF, rMTT, rTTP). Static [18F]FET-PET parameters including mean and maximum tumor to brain ratios (TBRmean, TBRmax) were calculated. Based on histopathology and radioclinical follow-up we diagnosed PD in 27 and RN in 10 cases. Using the receiver operating characteristic (ROC) analysis, area under the curve (AUC) values were calculated for single and multiparametric models. The performances of single and multiparametric approaches were assessed with analysis of variance and cross-validation.

RESULTS

After application of inclusion and exclusion criteria, we included 37 patients in this study. Regarding the in-sample based approach, in single parameter analysis rTBRmean (AUC = 0.91, p < 0.001), rTBRmax (AUC = 0.89, p < 0.001), rTTP (AUC = 0.87, p < 0.001) and rCBVmean (AUC = 0.84, p < 0.001) were efficacious for discrimination of PD from RN. The rCBFmean and rMTT did not reach statistical significance. A classification model consisting of TBRmean, rCBVmean and rTTP achieved an AUC of 0.98 (p < 0.001), outperforming the use of rTBRmean alone, which was the single parametric approach with the highest AUC. Analysis of variance confirmed the superiority of the multiparametric approach over the single parameter one (p = 0.002). While cross-validation attributed the highest AUC value to the model consisting of TBRmean and rCBVmean, it also suggested that the addition of rTTP resulted in the highest accuracy. Overall, multiparametric models performed better than single parameter ones.

CONCLUSION

A multiparametric MRI-PWI and [18F]FET-PET model consisting of TBRmean, rCBVmean and PWI rTTP significantly outperformed the use of rTBRmean alone, which was the best single parameter approach. Secondarily, we firstly report the potential usefulness of PWI rTTP for discrimination of PD from RN in patients with glioma; however, for validation of our findings the prospective studies with larger patient samples are necessary.

Prognostic Value of Genotype-Phenotype Correlations in X-Linked Myotubular Myopathy and the Use of the Face2Gene Application as an Effective Non-Invasive Diagnostic Tool

BACKGROUND

X-linked myotubular myopathy (XLMTM) is a rare congenital myopathy resulting from dysfunction of the protein myotubularin encoded by the MTM1 gene. XLMTM has a high neonatal and infantile mortality rate due to a severe myopathic phenotype and respiratory failure. However, in a minority of XLMTM cases, patients present with milder phenotypes and achieve ambulation and adulthood. Notable facial dysmorphia is also present.

METHODS

We investigated the genotype-phenotype correlations in newly diagnosed XLMTM patients in a patients' cohort (previously published data plus three novel variants, n = 414). Based on the facial gestalt difference between XLMTM patients and unaffected controls, we investigated the use of the Face2Gene application.

RESULTS

Significant associations between severe phenotype and truncating variants (p < 0.001), frameshift variants (p < 0.001), nonsense variants (p = 0.006), and in/del variants (p = 0.036) were present. Missense variants were significantly associated with the mild and moderate phenotype (p < 0.001). The Face2Gene application showed a significant difference between XLMTM patients and unaffected controls (p = 0.001).

CONCLUSIONS

Using genotype-phenotype correlations could predict the disease course in most XLMTM patients, but still with limitations. The Face2Gene application seems to be a practical, non-invasive diagnostic approach in XLMTM using the correct algorithm.

Enhanced expression of autophagy-related p62 without increased deposits of neurodegeneration-associated proteins in glioblastoma and surrounding tissue - An autopsy-based study

Neurodegenerative diseases are a major health burden. The underlying causes are not yet fully understood, but different mechanisms such as cell stress and chronic inflammation have been described as contributing factors. Neurodegenerative changes have been observed in the vicinity of brain tumors, typically around slowly growing benign lesions. Moreover, in‐vitro data suggest a potential induction of pathological tau deposits also in glioblastoma, a highly malignant and proliferative brain cancer. The aim of this study was to evaluate neurodegeneration‐associated protein deposition and autophagy as well as microglial activation within and surrounding glioblastoma. Post‐mortem brain tissue of 22 patients with glioblastoma was evaluated immunohistochemically for phosphorylated tau, beta‐amyloid, alpha‐synuclein and phosphorylated TDP‐43. Additionally, the autophagy marker p62 and the microglial marker HLA‐DR were investigated. The data was compared to 22 control cases and ten cases with other space occupying brain lesions. An increase of p62‐immunoreactivity was observed within and adjacent to the glioblastoma tumor tissue. Moreover, dense microglial infiltration in the tumor tissue and the immediate surrounding brain tissue was a constant feature. Deposition of neurodegeneration‐associated proteins was found in the majority of cases (86.4%) but in distant sites. These findings suggested a preexisting neurodegenerative pathology, which followed a typical distributional pattern: ten cases with Alzheimer disease neuropathological changes, including two severe cases, eight cases with primary age‐related tauopathy, six cases with aging‐related tau astrogliopathy and one case with progressive supranuclear palsy. Collectively, our data suggests enhanced autophagy in glioblastoma tumor cells and the surrounding brain. The variety and distribution of distant neurodegeneration‐associated protein aggregates observed in the majority of cases, suggest a preexisting rather than a tumor‐induced neurodegenerative condition.

Proteomic characterisation of polyglucosan bodies in skeletal muscle in RBCK1 deficiency

AIMS

Several neurodegenerative and neuromuscular disorders are characterised by storage of polyglucosan, consisting of proteins and amylopectin-like polysaccharides, which are less branched than in normal glycogen. Such diseases include Lafora disease, branching enzyme deficiency, glycogenin-1 deficiency, polyglucosan body myopathy type 1 (PGBM1) due to RBCK1 deficiency and others. The protein composition of polyglucosan bodies is largely unknown.

METHODS

We combined quantitative mass spectrometry, immunohistochemical and western blot analyses to identify the principal protein components of polyglucosan bodies in PGBM1. Histologically stained tissue sections of skeletal muscle from four patients were used to isolate polyglucosan deposits and control regions by laser microdissection. Prior to mass spectrometry, samples were labelled with tandem mass tags that enable quantitative comparison and multiplexed analysis of dissected samples. To study the distribution and expression of the accumulated proteins, immunohistochemical and western blot analyses were performed.

RESULTS

Accumulated proteins were mainly components of glycogen metabolism and protein quality control pathways. The majority of fibres showed depletion of glycogen and redistribution of key enzymes of glycogen metabolism to the polyglucosan bodies. The polyglucosan bodies also showed accumulation of proteins involved in the ubiquitin-proteasome and autophagocytosis systems and protein chaperones.

CONCLUSIONS

The sequestration of key enzymes of glycogen metabolism to the polyglucosan bodies may explain the glycogen depletion in the fibres and muscle function impairment. The accumulation of components of the protein quality control systems and other proteins frequently found in protein aggregate disorders indicates that protein aggregation may be an essential part of the pathobiology of polyglucosan storage.

Somatostatin Receptor Subtype Expression in Patients with Acromegaly and Complicated Clinical Course

Somatostatin analogues are considered to be the first line of treatment in acromegaly. Somatostatin analogues of the first generation mainly target the somatostatin receptor (SSTR) subtype 2 and have been proven efficient in the majority of patients with acromegaly. Pasireotide was the first somatostatin analogue also substantially targeting the SSTR subtype 5. An efficient drug for Cushing’s disease tailored to suboptimal-responding patients with acromegaly then became available. We immunohistochemically investigated SSTR subtypes expression in pituitary adenomas from operated acromegaly patients with clinical relapse and a complicated clinical course. Patients received pasireotide in the course of their disease. The predictive value of SSTR subtypes immunhistochemical analysis for the therapeutic response is discussed.

Giant silent corticotrope pituitary adenoma in a patient with complicated clinical course

Not required for Clinical Vignette.

A TOMM40/APOE allele encoding APOE-E3 predicts high likelihood of late-onset Alzheimer's disease in autopsy cases

BACKGROUND

The APOE-ε4 allele is an established risk factor for Alzheimer's disease (AD). TOMM40 located adjacent to APOE has also been implicated in AD but reports of TOMM40 associations with AD that are independent of APOE-ε4 are at variance.

METHODS

We investigated associations of AD with haplotypes defined by three TOMM40 and two APOE single nucleotide polymorphisms in 73 and 71 autopsy cases with intermediate and high likelihood of AD (defined by BRAAK stages

RESULTS

We observed eight haplotypes with a frequency >0.02. The two haplotypes encoding APOE-E4 showed strong associations with AD that did not differ between intermediate and high likelihood AD. In contrast, a TOMM40 haplotype encoding APOE-E3 was identified as risk haplotype of high- (p = .0186), but not intermediate likelihood AD (p = .7530). Furthermore, the variant allele of rs2075650 located in intron 2 of TOMM40, increased the risk of high-, but not intermediate likelihood AD on the APOE-ε3/ε3 background (p = .0230).

CONCLUSION

The striking association of TOMM40 only with high likelihood AD may explain some contrasting results for TOMM40 in clinical studies and may reflect an association with more advanced disease and/or suggest a role of TOMM40 in the pathogenesis of neurofibrillary tangles.

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Key Words

• APOE
• Alzheimer’ disease
• TOMM40
• beta-amyloid
• genetics
• haplotypes
• neurofibrillary tangles

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MESH Headings

• Aged
• Aged, 80 and over
• Alzheimer Disease/genetics
• Alzheimer Disease/pathology
• Apolipoproteins E/genetics
• Female
• Gene Frequency
• Haplotypes
• Humans
• Male
• Membrane Transport Proteins/genetics
• Mitochondrial Precursor Protein Import Complex Proteins
• Polymorphism, Single Nucleotide

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Grants

• V 344 Austrian Science Fund FWF
• Austrian Science Fund
• Kurt und Senta Herrmann Stiftung

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Affiliation(s)

Selma M. Soyal Institute of Pharmacology and ToxicologyParacelsus Medical UniversitySalzburgAustria
Markus Kwik Institute of Pharmacology and ToxicologyParacelsus Medical UniversitySalzburgAustria
Ognian Kalev Division of NeuropathologyNeuromed Campus, Kepler University HospitalLinzAustria
Stefan Lenz Division of NeuropathologyNeuromed Campus, Kepler University HospitalLinzAustria
Greta Zara Institute of Pharmacology and ToxicologyParacelsus Medical UniversitySalzburgAustria
Peter Strasser Institute of Laboratory MedicineParacelsus Medical UniversitySalzburgAustria
Wolfgang Patsch Institute of Pharmacology and ToxicologyParacelsus Medical UniversitySalzburgAustria
Serge Weis Division of NeuropathologyNeuromed Campus, Kepler University HospitalLinzAustria

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Functional characterization of GYG1 variants in two patients with myopathy and glycogenin-1 deficiency

Glycogen storage disease XV is caused by variants in the glycogenin-1 gene, GYG1, and presents as a predominant skeletal myopathy or cardiomyopathy. We describe two patients with late-onset myopathy and biallelic GYG1 variants. In patient 1, the novel c.144-2A>G splice acceptor variant and the novel frameshift variant c.631delG (p.Val211Cysfs*30) were identified, and in patient 2, the previously described c.304G>C (p.Asp102His) and c.487delG (p.Asp163Thrfs*5) variants were found. Protein analysis showed total absence of glycogenin-1 expression in patient 1, whereas in patient 2 there was reduced expression of glycogenin-1, with the residual protein being non-functional. Both patients showed glycogen and polyglucosan storage in their muscle fibers, as revealed by PAS staining and electron microscopy. Age at onset of the myopathy phenotype was 53 years and 70 years respectively, with the selective pattern of muscle involvement on MRI corroborating the pattern of weakness. Cardiac evaluation of patient 1 and 2 did not show any specific abnormalities linked to the glycogenin-1 deficiency. In patient 2, who was shown to express the p.Asp102His mutated glycogenin-1, cardiac evaluation was still normal at age 77 years. This contrasts with the association of the p.Asp102His variant in homozygosity with a severe cardiomyopathy in several cases with an onset age between 30 and 50 years. This finding might indicate that the level of p.Asp102His mutated glycogenin-1 determines if a patient will develop a cardiomyopathy.

Case of the month 1-2019: CNS high-grade neuroepithelial tumor with BCOR alteration

No abstract available.

Progressive Multifocal Leukoencephalopathy Following Combined Rituximab-Based Immune-Chemotherapy for Post-transplant Lymphoproliferative Disorder in a Renal Transplant Recipient: A Case Report

BACKGROUND

Transplant recipients are at risk of developing progressive multifocal leukoencephalopathy (PML), an opportunistic infection due to reactivation of JC virus. Post-transplant lymphoproliferative disorders (PTLDs) represent a common malignancy in this population, and antiCD20-therapy has become an established component of its treatment.

CASE PRESENTATION

We describe the first case of a renal allograft transplant recipient with PTLD who received rituximab-based immune-chemotherapy and developed PML shortly thereafter. Despite early suspicion and diagnosis, the disease ran a relentlessly progressive course, and the patient succumbed to his illness shortly thereafter.

CONCLUSION

PML should be strongly suspected whenever unusual neurologic symptoms appear in the context of immunosuppression. Clinicians and patients should be aware of the potential for PML after rituximab therapy.

Evaluation of Clinical and Paraclinical Findings for the Differential Diagnosis of Autoimmune and Infectious Encephalitis

Background: The differential diagnosis of autoimmune and infectious encephalitis is notoriously difficult. For this study, we compare the presenting clinical symptoms and paraclinical test results of autoimmune and infectious encephalitis patients. A clinical algorithm for the diagnosis of autoimmune encephalitis has recently been published. We test these Graus criteria on our cohort for diagnostic sensitivity and specificity within the first week of presentation. Methods: We included all patients seen at our department within a 10-year-period who were diagnosed with encephalitis. The discharge diagnoses served as the reference standard for testing the clinical algorithm for two conditions: use of all the clinical information available on a patient during the first week of hospital admission assuming undefined autoantibody status and microbiological test results (C1) vs. consideration of all the information available on a patient, including the results of serological and microbiological testing (C2). Results: Eighty-four patients (33 autoimmune, 51 infectious encephalitis) were included in the study. Fifty-one (17 autoimmune, 34 infectious) had a definite clinical diagnosis. The two groups differed significantly for the presence of headache, fever, epileptic seizures, and CSF cell-count at presentation. Application of the clinical algorithm resulted in a low sensitivity (58%) and very low specificity (8%) for the diagnosis of possible autoimmune encephalitis. The latter increased considerably in the subgroups of probable and definite autoimmune encephalitis. Whereas the sensitivity of the individual diagnostic categories was clearly time-dependent, the specificity rested foremost on the knowledge of the results of microbiological testing. Anti-CASPR2- and -LGI1-associated autoimmune encephalitis and tick-borne virus encephalitis presented particular diagnostic pitfalls. Conclusions: We define clinical symptoms and paraclinical test results which prove valuable for the differentiation between infectious and autoimmune encephalitis. Sensitivity and specificity of the clinical algorithm clearly depended on the amount of time passed after hospital admission and knowledge of microbiological test results. Accepting this limitation for the acute setting, the algorithm remains a valuable diagnostic aid for antibody-negative autoimmune encephalitis or in resource-poor settings. The initiation of immune therapy however should not be delayed if an autoimmune etiology is considered likely, even if the diagnostic criteria of the algorithm are not (yet) fulfilled.

17q21.31 duplication causes prominent tau-related dementia with increased MAPT expression

To assess the role of rare copy number variations in Alzheimer's disease (AD), we conducted a case-control study using whole-exome sequencing data from 522 early-onset cases and 584 controls. The most recurrent rearrangement was a 17q21.31 microduplication, overlapping the CRHR1, MAPT, STH and KANSL1 genes that was found in four cases, including one de novo rearrangement, and was absent in controls. The increased MAPT gene dosage led to a 1.6-1.9-fold expression of the MAPT messenger RNA. Clinical signs, neuroimaging and cerebrospinal fluid biomarker profiles were consistent with an AD diagnosis in MAPT duplication carriers. However, amyloid positon emission tomography (PET) imaging, performed in three patients, was negative. Analysis of an additional case with neuropathological examination confirmed that the MAPT duplication causes a complex tauopathy, including prominent neurofibrillary tangle pathology in the medial temporal lobe without amyloid-β deposits. 17q21.31 duplication is the genetic basis of a novel entity marked by prominent tauopathy, leading to early-onset dementia with an AD clinical phenotype. This entity could account for a proportion of probable AD cases with negative amyloid PET imaging recently identified in large clinical series.

Familial early-onset dementia with complex neuropathologic phenotype and genomic background

Despite significant progress in our understanding of hereditary neurodegenerative diseases, the list of genes associated with early-onset dementia is not yet complete. In the present study, we describe a familial neurodegenerative disorder characterized clinically as the behavioral and/or dysexecutive variant of Alzheimer's disease with neuroradiologic features of Alzheimer's disease, however, lacking amyloid-β deposits in the brain. Instead, we observed a complex, 4 repeat predominant, tauopathy, together with a TAR DNA-binding protein of 43 kDa proteinopathy. Whole-exome sequencing on 2 affected siblings and 1 unaffected aunt uncovered a large number of candidate genes, including LRRK2 and SYNE2. In addition, DDI1, KRBA1, and TOR1A genes possessed novel stop-gain mutations only in the patients. Pathway, gene ontology, and network interaction analysis indicated the involvement of pathways related to neurodegeneration but revealed novel aspects also. This condition does not fit into any well-characterized category of neurodegenerative disorders. Exome sequencing did not disclose a single disease-specific gene mutation suggesting that a set of genes working together in different pathways may contribute to the etiology of the complex phenotype.

Polyglucosan body myopathy caused by defective ubiquitin ligase RBCK1

Glycogen storage diseases are important causes of myopathy and cardiomyopathy. We describe 10 patients from 8 families with childhood or juvenile onset of myopathy, 8 of whom also had rapidly progressive cardiomyopathy, requiring heart transplant in 4. The patients were homozygous or compound heterozygous for missense or truncating mutations in RBCK1, which encodes for a ubiquitin ligase, and had extensive polyglucosan accumulation in skeletal muscle and in the heart in cases of cardiomyopathy. We conclude that RBCK1 deficiency is a frequent cause of polyglucosan storage myopathy associated with progressive muscle weakness and cardiomyopathy.

[Orbital lymphoma]

INTRODUCTION

Orbital lymphomas are neoplasms with increasing incidence in recent years in immunocompromised, as well as immunocompetent patients, which defines their social importance.

AIM

To describe and analyze the experience of the University hospital "'Sv. Ivan Rilski" with the treatment of this pathology for the period 1997-2008.

MATERIAL AND METHODS

Fourteen patients (8 females, 6 males - 13 primary orbital lymphomas, 1 systemic lymphoma). Mean age at diagnosis was 65.6 years (from 50 to 80 years). In 2/3 of the patients the lesion was localized in left eye, without a case with bilateral orbital involvement. Seven cases the diagnosis was made 6 months from the onset of symptoms, 5 cases - 1 year and 2 cases - more than one year. The most common clinical symptoms were exophthalmus (12 case), tumor or bulging mass of the eyelid - 8, diplopy - 6, decreased visual acuity - 5. Intraconal localization of the tumor was in 6 cases, extraconal - 2. intra-extraconal - 6. The diagnosis was made by neuro-ophthalmologist and precised with the aid of CT and MRI. All the patients were operated on with the following approaches - fronto-orbital - 9 cases, lateral - 3, anterior orbitotomy (without bone resection) - 2 cases. In six cases "'gross total" resection was achieved, in the rest of the cases the resection was partial. On histological examination, a high grade lymphoma was established in 2 cases with primary orbital lymphoma and one case with systemic lymphoma. All other cases were diagnosed as low-grade B-call small lymphocytic non-Hodgkin's lymphoma. Long-term survival (over 5 years) was observed in 4 cases with primary lymphoma, whereas the patient with systemic form of the disease died 10 months after the operation.

Ependymoma of the cauda equina starting with communicating hydrocephalus: a case report

The presence of concomitant hydrocephalus in cases with spinal cord tumors is relatively rare. Here, we describe a case of myxopapillary ependymoma of the cauda equina starting with communicating hydrocephalus in a 14-year-old boy. The patient presented to the clinic without underlying causes of hydrocephalus on the neuroimaging data. After ventriculoperitoneal shunt placement, despite the numerous malfunction incidents, the patient was doing well. Eight years later, he developed progressive weakness and coldness of the lower limbs. Multiple cystic lesions in the cervicothoracic area were found on magnetic resonance imaging. Decompressive hemilaminectomy of the cervicothoracic region was performed with temporary improvement of the patient's condition. Because of persisting complaints, the sacral area of the spine was also observed and neuroimaging data for a tumoral lesion in the cauda equina region were found. The lesion was surgically removed and the histological result was myxopapillary ependymoma. Therefore, cases presenting with internal hydrocephalus without clear-cut intracranial etiology should have detailed neuroimaging of the whole central nervous system.

The prion protein in human neuromuscular diseases

The basis of human prion diseases affecting the nervous system is accumulation of a disease-associated conformer (PrPSc) of the normal cellular prion protein (PrPC). Earlier studies demonstrated increased expression of PrPC in inclusion body myositis (IBM), dermato-, and polymyositis, as well as neurogenic muscle atrophy. To define the spectrum and reliability of PrPC immunoreactivity, its expression was examined systematically in a series of pathologically characterized muscular disorders by means of immunohistochemistry, confocal laser microscopy, and immunogold electron microscopy. Anti-PrPC immunolabelling of rimmed vacuoles was observed in IBM, inclusions of myofibrillary myopathy, targets, regenerating, and atrophic fibres, mononuclear cells, in addition to ragged red fibres in mitochondrial myopathies, and focal sarcolemmal immunostaining in non-diseased controls. Quantitative analysis demonstrated that, in neurogenic muscle lesions, anti-PrPC staining detects a significantly broader spectrum of fibres than anti-vimentin or anti-NCAM. In dystrophic muscle, PrPC expression was mainly restricted to regenerating fibres. In IBM, PrPC expression was not confined to rimmed vacuoles or vacuolated fibres and only a small percentage (7.1%) of rimmed vacuoles were PrPC positive. Ultrastructurally, PrPC was observed in the cytoplasm of lymphocytes, in the myofibrillar network of targets, and in rimmed vacuoles. Knowledge of disease circumstances with altered expression of PrPC is important in the setting of a potentially increased chance for extraneural PrPC-PrPSc conversion. In addition, our observations suggest that PrPC may have a general stress-response effect in various neuromuscular disorders.

Contribution of neuropathology to the understanding of human prion disease

Neuropathology is an important tool for definitive diagnosis of sporadic, genetic, and acquired prion disease. Classical neuropathological hallmark is the highly disease-specific spongiform change accompanied by neuronal loss, astro- and microgliosis. Spongiform change of the neuropil consists of either microcystic or confluent vacuoles and varies greatly within the same brain. In addition, the most important aspect of confirmatory diagnosis is the demonstration of disease-associated prion protein (PrP(d)) by immunohistochemistry or Western blotting. Different PrP(d) immunostaining patterns include patchy/perivacuolar surrounding spongiform change, diffuse/synaptic, perineuronal, or plaque type. The latter includes unicentric kuru-type plaques or multicentric plaques as in the peculiar genetic prion disorder, Gerstmann-Sträussler-Scheinker disease. PrP(d) immunostaining patterns correlate well with phenotypes defined by the polymorphic codon 129 and the type of protease resistant PrP(d) seen on Western blots. PrP(d) immunoreactivity in the cerebellum may be highly informative about disease subtypes. Although the central nervous system is the major site of PrP(d) accumulation, it may also be observed in peripheral nerves as adaxonal deposits; in skeletal muscle as granular immunoreactivity in particular in abundance in a unique instance of concomitant Creutzfeldt-Jakob disease and inclusion body myositis; as well as associated with dendritic cells and macrophages in vessel walls. A subset of inhibitory GABAergic neurons is selectively affected in experimental and human prion disease. The central pathogenetic cascade includes oxidative stress and apoptosis. Deposition of terminal complement components on neurons accompanies tissue damage.