A subtype of sporadic prion disease mimicking fatal familial insomnia.
ABSTRACT To establish a variant of sporadic prion disease as the sporadic form of fatal familial insomnia (FFI).
FFI is a recently described prion disease characterized clinically by severe sleep impairment, dysautonomia, and motor signs, and pathologically by atrophy of thalamic nuclei, especially the medial dorsal and anterior ventral, and of the inferior olive. FFI is linked to the D178N mutation coupled with the methionine codon at position 129 in the prion protein gene (PRNP). It is also identified by the properties of the abnormal prion protein (PrP(Sc)), which has the relative molecular mass of 19 kDa, corresponding to the so-called type 2, and a marked underrepresentation of the unglycosylated form relative to the diglycosylated and monoglycosylated forms.
Clinical, pathologic, PrP(Sc), and PRNP data from 5 subjects with a sporadic prion disease phenotypically similar to FFI were collected and analyzed.
All 5 subjects had a disease clinically similar and histopathologically virtually identical to FFI. PrP(Sc) type 2 was present in all subjects in amount and distribution similar to those of FFI. However, the PrP(Sc) did not show the striking underrepresentation of the unglycosylated isoform of the protein that is characteristic of FFI. Moreover, none of the subjects had the D178N PRNP mutation but all were homozygous for methionine at codon 129.
This condition is likely to represent the sporadic form of FFI and the term "sporadic fatal insomnia" is proposed.
SourceAvailable from: Giuseppe Legname[Show abstract] [Hide abstract]
ABSTRACT: Prion diseases are fatal neurodegenerative illnesses, which include Creutzfeldt-Jakob disease in humans and scrapie, chronic wasting disease, and bovine spongiform encephalopathy in animals. They are caused by unconventional infectious agents consisting primarily of misfolded, aggregated, β -sheet-rich isoforms, denoted prions, of the physiological cellular prion protein (PrP(C)). Many lines of evidence suggest that prions (PrP(Sc)) act both as a template for this conversion and as a neurotoxic agent causing neuronal dysfunction and cell death. As such, PrP(Sc) may be considered as both a neuropathological hallmark of the disease and a therapeutic target. Several diagnostic imaging probes have been developed to monitor cerebral amyloid lesions in patients with neurodegenerative disorders (such as Alzheimer's disease, Parkinson's disease, and prion disease). Examples of these probes are Congo red, thioflavin T, and their derivatives. We synthesized a series of styryl derivatives, denoted theranostics, and studied their therapeutic and/or diagnostic potentials. Here we review the salient traits of these small molecules that are able to detect and modulate aggregated forms of several proteins involved in protein misfolding diseases. We then highlight the importance of further studies for their practical implications in therapy and diagnostics.International Journal of Cell Biology 11/2013; 2013:150952. DOI:10.1155/2013/150952
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ABSTRACT: In clinical practice signal hyperintensity in the cortex and/or in the striatum on magnetic resonance (MR) diffusion-weighted images (DWI) is a marker of sporadic Creutzfeldt–Jakob Disease (sCJD). MR diagnostic accuracy is greater than 90%, but the biophysical mechanisms underpinning the signal abnormality are unknown. The aim of this prospective study is to combine an advanced DWI protocol with new mathematical models of the microstructural changes occurring in prion disease patients to investigate the cause of MR signal alterations. This underpins the later development of more sensitive and specific image-based biomarkers. DWI data with a wide a range of echo times and diffusion weightings were acquired in 15 patients with suspected diagnosis of prion disease and in 4 healthy age-matched subjects. Clinical diagnosis of sCJD was made in nine patients, genetic CJD in one, rapidly progressive encephalopathy in three, and Gerstmann–Sträussler–Scheinker syndrome in two. Data were analysed with two bi-compartment models that represent different hypotheses about the histopathological alterations responsible for the DWI signal hyperintensity. A ROI-based analysis was performed in 13 grey matter areas located in affected and apparently unaffected regions from patients and healthy subjects. We provide for the first time non-invasive estimate of the restricted compartment radius, designed to reflect vacuole size, which is a key discriminator of sCJD subtypes. The estimated vacuole size in DWI hyperintense cortex was in the range between 3 and 10 µm that is compatible with neuropathology measurements. In DWI hyperintense grey matter of sCJD patients the two bi-compartment models outperform the classic mono-exponential ADC model. Both new models show that T2 relaxation times significantly increase, fast and slow diffusivities reduce, and the fraction of the compartment with slow/restricted diffusion increases compared to unaffected grey matter of patients and healthy subjects. Analysis of the raw DWI signal allows us to suggest the following acquisition parameters for optimized detection of CJD lesions: b = 3000 s/mm2 and TE = 103 ms. In conclusion, these results provide the first in vivo estimate of mean vacuole size, new insight on the mechanisms of DWI signal changes in prionopathies and open the way to designing an optimized acquisition protocol to improve early clinical diagnosis and subtyping of sCJD.11/2014; DOI:10.1016/j.nicl.2014.11.017
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ABSTRACT: A novel point mutation resulting in a glutamate-to-glycine substitution in PRNP at codon 200, E200G with codon 129 MV polymorphism (cis valine) and type 2 PrPSc was identified in a patient with a prolonged disease course leading to pathology-proven Jakob-Creutzfeldt disease. Despite the same codon as the most common genetic form of human PRNP mutation, E200K, this novel mutation (E200G) presented with a different clinical and pathological phenotype, including prolonged duration, large vacuoles, no vacuolation in the hippocampus, severe neuronal loss in the thalamus, mild cerebellar involvement, and abundant punctate linear and curvilinear deposition of PrPSc in synaptic boutons and axonal terminals along the dendrites.12/2013; 1(1):80. DOI:10.1186/2051-5960-1-80