Diffusion-weighted MRI in familial Creutzfeldt–Jakob disease with the codon 200 mutation in the prion protein gene

Cerebrospinal fluid neurofilament light levels in neurodegenerative dementia: Evaluation of diagnostic accuracy in the differential diagnosis of prion diseases

INTRODUCTION

Neurofilament light (NFL) levels in the cerebrospinal fluid are increased in several neurodegenerative dementias. However, their diagnostic accuracy in the differential diagnostic context is unknown.

METHODS

Cerebrospinal fluid NFL levels were quantified in nonprimarily neurodegenerative neurological and psychiatric diseases (n = 122), mild cognitive impairment (n = 48), Alzheimer's disease (n = 108), dementia with Lewy bodies/Parkinson's disease dementia (n = 53), vascular dementia (n = 46), frontotemporal dementia (n = 41), sporadic Creutzfeldt-Jakob disease (sCJD, n = 132), and genetic prion diseases (n = 182).

RESULTS

The highest NFL levels were detected in sCJD, followed by vascular dementia, frontotemporal dementia, dementia with Lewy bodies/Parkinson's disease dementia, Alzheimer's disease, and mild cognitive impairment. In sCJD, NFL levels correlated with cerebrospinal fluid tau and disease duration. NFL levels were able to differentiate sCJD from nonprimarily neurodegenerative neurological and psychiatric diseases (area under the curve = 0.99, 95% confidence interval: 0.99-1) and from the other diagnostic groups showing cognitive impairment/dementia of a non-CJD etiology (area under the curve = 0.90, 95% confidence interval: 0.87-0.92). Compared to nonprimarily neurodegenerative neurological and psychiatric diseases, NFL was also elevated in genetic prion diseases associated with the E200K, V210I, P102L, and D178N prion protein gene mutations.

DISCUSSION

Increased NFL levels are a common feature in neurodegenerative dementias.

[Creutzfeldt-Jakob disease: clinical and diagnostic aspects]

In this article, authors analyzed a modern approach to the diagnosis of Creutzfeldt-Jakob disease (CJD) based on the clinical signs, cerebrospinal fluid markers, electroencephalography and magnetic resonance imaging. It was demonstrated for the first time that patients with late-onset CJD differed from younger CJD patients with respect to MRI profiles and initial clinical presentation. To date, cerebrospinal fluid (CSF) analysis, particularly protein 14-3-3 testing, presents an important approach to the identification of disease cases. A spectrum of differential diagnosis of rapid progressive dementia varied from neurodegenerative dementias to dementia due to acute neurological conditions. Real-time quaking-induced conversion (RT-QuIC) allows the amplification of miniscule amounts of scrapie prion protein. Recent studies applied the RT-QuIC methodology to CSF for the diagnosis of human prion diseases.

Imaging of prion diseases

Prion diseases are caused by self-replicating proteins that induce lethal neurodegenerative disorders. In the last decade, the understanding of the different clinical, pathological, and neuroimaging phenotypes of this group of disorders has evolved paralleling the advances in prion molecular biology. From an imaging standpoint, the implementation of diffusion-weighted imaging in routine practice has markedly facilitated the detection of prion diseases, especially Creutzfeldt-Jakob. Less frequent prion-related disorders, including genetic diseases, may also benefit from progresses in the field of quantitative diffusion-weighted imaging, MR spectroscopy or molecular imaging. Herein, we present a review of the neuroimaging features of the prion disorders known to affect humans emphasizing the important contribution of MRI in the diagnosis of this group of disorders.

Codon 200 mutation of the prion gene: genotype-phenotype correlations

Genetic mutations as a cause of prion diseases are rare. We describe a large family with multiple affected members with the codon E200K prion mutation. To improve understanding of the genotype-phenotype correlations of prion gene mutations, clinical, genetic and neuropathological data were obtained from family members over 15 years. Six patients with the codon E200K mutation and 2 patients without the codon 200 mutation from this family were followed. The 6 patients with the codon 200 mutation had a mean age onset of 58.83 years (SD 7.2; lower 95 % CI 51.0; upper 95 % CI 66.4). The most common symptoms at onset were memory loss, walking difficulties and hallucinations. The most frequent neurological phenomena were a rapidly progressive dementia, eye movement abnormalities and ataxia. The mean duration of onset of symptoms to death was 3.9 months (SD 1.1; lower 95 % CI 2.8; upper 95 % CI 5.1). Two male patients developed neurodegenerative disorders unrelated to the prion codon 200 mutation: progressive supranuclear palsy and olivopontocerebellar degeneration. Their mean survival was 96 months (SD 33.9; p < 0.0001). Individuals from families with the prion codon 200 mutation may have a rapidly progressive dementia. Members of families with inherited prion mutations may be at risk of other neurodegenerative disorders unrelated to the prion mutation.

Creutzfeldt-Jakob disease with PRNP G114V mutation in a Chinese family

BACKGROUND

Recent evidence has shown clinical phenotypic heterogeneity of inherited prion diseases, even between patients harbouring the same mutation in the PRNP gene.

OBJECTIVE AND METHODS

We collected clinical data from a Chinese family with autosomal dominant dementia and screened the PRNP gene on 28 living members. A stereotactic biopsy of the right frontal lobe of the proband was performed.

RESULTS

The family comprised four affected individuals within two successive generations. The age of onset was in 30 or 40 s, and the duration was about 2-3 years. Clinical features of the affected members included neuropsychiatric disturbances, progressive dementia and extrapyramidal symptoms. Immunostaining for prion protein showed fine granular deposits of PrP(sc) in the neuropil. The PRNP gene analysis demonstrated a heterozygous G114V mutation in 15 family members. The proband was diagnosed as familial Creutzfeldt-Jakob disease (fCJD).

CONCLUSION

This study strengthens the linkage of the G114V mutation to CJD. It supports the worldwide distribution of fCJD despite differences in genetic background.

MR imaging of familial Creutzfeldt-Jakob disease: a blinded and controlled study

BACKGROUND AND PURPOSE

The E200K mutation of the PRNP (prion protein) gene is the most common cause of familial Creutzfeldt-Jakob disease (fCJD), which has imaging and clinical features that are similar to the sporadic form. The purpose of this study was to conduct a controlled and blinded evaluation of the sensitivity and specificity of MR imaging in this unique population.

MATERIALS AND METHODS

We compared the MR imaging characteristics of 15 early stage familial CJD patients (age, 60 +/- 7 years) with a group of 22 healthy subjects from the same families (age, 61 +/- 8 years). MR imaging included diffusion-weighted imaging (DWI), T2-weighted fast spin-echo imaging, and a fluid-attenuated inversion recovery (FLAIR) sequence. The scans were rated for abnormalities by an experienced neuroradiologist blind to diagnosis, group assignment, age, and sex.

RESULTS

Thirteen of 15 fCJD subjects had abnormal MR imaging. FLAIR signal intensity abnormality in the caudate or putamen nuclei demonstrated a sensitivity of 87% and specificity of 91%. DWI abnormality in the caudate nucleus showed a sensitivity of 73% and a specificity of 100%. Abnormalities in the thalamus (6 patients), cingulate gyrus (6 patients), frontal lobes (4 patients), and occipital lobes (3 patients) were best detected with DWI. No signal intensity abnormalities were demonstrated in the cerebellum. T2-weighted and T1-weighted sequences were uninformative.

CONCLUSIONS

FLAIR and DWI abnormalities in the caudate nucleus and putamen offer the best sensitivity and specificity for diagnosing fCJD. Our findings support recent recommendations that MR imaging should be added to the diagnostic evaluation of CJD.

Aquaporin 1 and aquaporin 4 overexpression in bovine spongiform encephalopathy in a transgenic murine model and in cattle field cases

Aquaporins (AQP) are a family of transmembrane proteins that act as water selective channels. AQP1 and AQP4 are widely expressed in the central nervous system where they play several roles. Overexpression of AQP has been reported in some human and animal transmissible spongiform encephalopathies, but information is scanty about their distribution in the central nervous system in bovine spongiform encephalopathy (BSE). Double immunohistochemistry for AQP1, AQP4 and GFAP was developed in a transgenic mouse line overexpressing the bovine cellular prion protein (BoTg110), intracerebrally infected with cattle BSE. Western blot for AQP1 and AQP4, and immunohistochemistry for both AQP and GFAP were carried out in cases of BSE-diagnosed cattle as part of surveillance plan in Catalonia (Spain). A marked increase in AQP1 and AQP4 was observed in mice at the terminal stage of the disease, when they had a wide range of clinical signs, whereas no increase could be observed in the early stage before the onset of the clinical signs. In cattle which did not show evidence of clinical signs, both AQP already showed a great increase. The AQP overexpression correlated with GFAP-immunoreactive astrocytes and PrPres deposition in both cases. The results of this study suggest that AQP overexpression in glial cells could lead to an imbalance in water and ion homeostasis which could contribute to triggering the typical histopathological changes of BSE.

Increased expression of water channel aquaporin 1 and aquaporin 4 in Creutzfeldt-Jakob disease and in bovine spongiform encephalopathy-infected bovine-PrP transgenic mice

Spongiform change is a cardinal feature in transmissible spongiform encephalopathies, including Creutzfeldt-Jakob disease (CJD) and bovine spongiform encephalopathy (BSE). It is characterized by swelling of the neuronal processes and vacuolization of the neuropil, leading to increased intraneuronal water content. The present study examines, by gel electrophoresis and Western blotting, the expression levels of the water channels aquaporin 1 (AQP1) and aquaporin 4 (AQP4) in the frontal cortex (area 8) homogenates of sporadic CJD cases (six men, four women; seven cases with methionine/methionine at codon 129 and PrP type 1; two cases with valine/valine at codon 129 and PrP type 2, and one case methionine/valine at codon 129 and PrP type 1) compared with age-matched controls, and cases with Alzheimer's disease (AD, stage VI of Braak and Braak) and diffuse Lewy body disease (DLB). AQP1 and AQP4 protein levels were also studied in the cerebral cortex of BSE-infected bovine-PrP transgenic mice (BoPrP-Tg110 mice) examined at 60, 150, 210 and 270 days post-inoculation (dpi) compared with healthy brain-inoculated control mice. Quantitative densitometry of AQP bands normalized for beta-actin was analyzed using Statgraphics plus 5.0 software from ANOVA and LSD statistical tests. Significant increased expression levels of AQP1 (as revealed with two different antibodies) and AQP4 were seen in CJD, but not in advanced AD and DLB cases when compared with controls. Immunohistochemistry revealed that AQP1 and AQP4 were expressed in astrocytes in diseased cases. No modifications in the expression levels of AQP1 and AQP4 were observed in BSE-infected bovine-PrP transgenic mice at 60, 150 and 210 dpi. However, a significant increase in the expression levels of AQP1 and AQP4 was found in mice at 270 dpi, the time corresponding with the appearance of PrP(res) immunoreactivity in Western blots and typical spongiform lesions in the brain. Together, these findings show increased expression of water channels in the brain in human and animal prion diseases. These modifications may have implications in the regulation of water transport in astrocytes and may account for an imbalance in water and ion homeostasis in prion diseases.

The imaging appearance of Creutzfeldt-Jakob disease caused by the E200K mutation

The E200K mutation on chromosome 20 can cause familial Creutzfeldt-Jakob disease (CJD). Patients with this mutation are clinically similar to those with sporadic CJD, but their imaging features are not well documented. We report here the quantitative and qualitative evaluation of the magnetic resonance (MR) imaging characteristics of this unique group of patients using three-dimensional spoiled gradient recalled (SPGR) echo images, diffusion-weighted imaging (DWI) with apparent diffusion coefficient (ADC) measurements, MR spectroscopy and a fluid-attenuated inversion recovery (FLAIR) sequence. The SPGR and ADC data were analyzed with SPM99. ANCOVA and regression models were used for a region-of-interest (ROI) analysis of ADC and metabolic ratios. CJD patients had a decreased fraction of gray matter and an increased fraction of cerebrospinal fluid (P=.001) in the cortex and cerebellum and increased ADC values in the cortex (P<.001). Focal decreases of ADC were found in the putamen via ROI analysis (548+/-83 vs. 709+/-9 microm(2)/s, P=.02). N-acetyl aspartate (NAA) was generally reduced, with the NAA/Cho ratio lowest in the cingulate gyrus. Qualitative assessment revealed hyperintensities on FLAIR, DWI or both in the putamen (three out of four patients), caudate (three out of four patients) and thalamus. These results provide a framework for future study of patients with genetically defined familial CJD.