Annemieke M. Rozemuller

Quantifying prion disease penetrance using large population control cohorts

Large genomic reference data sets reveal a spectrum of pathogenicity in the prion protein gene and provide genetic validation for a therapeutic strategy in prion disease. Share trumps rare No longer just buzz words, “patient empowerment” and “data sharing” are enabling breakthrough research on rare genetic diseases. Although more than 100,000 genetic variants are believed to drive disease in humans, little is known about penetrance—the probability that a mutation will actually cause disease in the carrier. This conundrum persists because small sample sizes breed imperfect alliance estimates between mutations and disease risk. Now, a patient-turned-scientist joined with a large bioinformatics team to analyze vast amounts of shared data—from the Exome Aggregation Consortium and the 23andMe database—to provide insights into genetic-variant penetrance and possible treatment approaches for a rare, fatal genetic prion disease. More than 100,000 genetic variants are reported to cause Mendelian disease in humans, but the penetrance—the probability that a carrier of the purported disease-causing genotype will indeed develop the disease—is generally unknown. We assess the impact of variants in the prion protein gene (PRNP) on the risk of prion disease by analyzing 16,025 prion disease cases, 60,706 population control exomes, and 531,575 individuals genotyped by 23andMe Inc. We show that missense variants in PRNP previously reported to be pathogenic are at least 30 times more common in the population than expected on the basis of genetic prion disease prevalence. Although some of this excess can be attributed to benign variants falsely assigned as pathogenic, other variants have genuine effects on disease susceptibility but confer lifetime risks ranging from <0.1 to ~100%. We also show that truncating variants in PRNP have position-dependent effects, with true loss-of-function alleles found in healthy older individuals, a finding that supports the safety of therapeutic suppression of prion protein expression.

The spectrum of MR detectable cortical microinfarcts: a classification study with 7-tesla postmortem MRI and histopathology.

Cerebral microinfarcts (CMIs) are common neuropathologic findings in aging and dementia. We explored the spectrum of cortical CMIs that can be visualized with 7T magnetic resonance imaging (MRI). Thirty-three coronal brain slices of 11 individuals with neuropathologically confirmed dementia were subjected to a high-resolution postmortem 7T MRI protocol. First, we identified all visible small (ue4255u2009mm) intracortical and juxtacortical lesions on postmortem MRI. Lesions were classified as CMI or nonCMI based on histology, and their MR features were recorded. Thirty lesions were identified on the initial MRI evaluation, of which twenty-three could be matched with histology. Histopathology classified 12 lesions as CMIs, all of which were located intracortically. On the basis of their MR features, they could be classified as chronic gliotic CMIs—with or without cavitation or hemorrhagic components—and acute CMIs. Eleven MRI identified lesions were not of ischemic nature and most commonly enlarged or atypically shaped perivascular spaces. Their MRI features were similar to gliotic CMIs with or without cavitation, but these ‘CMI mimics’ were always located juxtacortically. 7T postmortem MRI distinguishes different histopathologic types of cortical CMIs, with distinctive MR characteristics. On the basis of our findings, we propose in vivo rating criteria for the detection of intracortical CMIs.

Inherited Creutzfeldt–Jakob disease in a Dutch patient with a novel five octapeptide repeat insertion and unusual cerebellar morphology

An atypical case of inherited Creutzfeldt–Jakob disease (CJD) is described in a 35-year-old Dutch woman, homozygous for methionine at codon 129 of the prion protein gene (PRNP). The clinical phenotype was characterised by slowly progressive cognitive decline and parkinsonism. Neuropathological findings consisted of scanty spongiosis and only faint to absent immunohistochemical staining for the abnormal prion protein, PrPSc, with patchy deposits in the cerebellar cortex. Purkinje cells were abnormally located in the molecular layer of the cerebellum. Western blot analysis showed the co-occurrence of PrPSc types 1 and 2 with an unusual distribution. Sequence analysis disclosed a novel 120 bp insertion in the octapeptide repeat region of the PRNP, encoding five additional R2 octapeptide repeats. These features define an unusual neuropathological phenotype and novel genotype, further expanding the spectrum of genotype–phenotype correlations in inherited prion diseases and emphasising the need to carry out pre-mortem PRNP sequencing in all young patients with atypical dementias.

The first case of fatal familial insomnia (ffi) in the netherlands: A patient from egyptian descent with concurrent four repeat tau deposits

Transmissible spongiform encephalopathies or prion diseases are a unique group of neurodegenerative disorders, occurring as sporadic, inherited or acquired forms [1]. These diseases are caused by accumulation in the brain of protease resistant PrP, an abnormal structural conformer of the cellular protein PrP [2,3]. In humans, inherited prion diseases are associated with three major phenotypes: Creutzfeldt-Jakob disease (CJD), GerstmannSträussler-Scheinker disease and fatal familial insomnia (FFI). The c.532G>A, p.Asp178Asn mutation, also known as the D178N mutation, in the prion protein gene (PRNP) is the only known mutation associated with FFI [4]. The same mutation is also associated with a CJD phenotype depending on the genotype at the polymorphic codon 129 on the mutated allele; the methionine allele is linked to FFI, whereas the valine allele is associated with a CJD phenotype [5]. The onset of FFI is in middle to late adulthood, although age at onset under 30 years has been reported in eight patients worldwide [6]. Clinical signs involve disturbances of the wake and sleep cycle, autonomic disorders, motor abnormalities, myoclonus and cognitive decline [7]. In its classical form, neuropathological features consist of thalamic and olivary degeneration with mild degrees of spongiform change in the cerebral cortex, absence of amyloid and low levels of PrP deposition throughout affected brain regions [8]. Tauopathy, which is sometimes seen in prion diseases with amyloidosis, has thus far not been reported in patients with FFI. In this report, we describe an unusual neuropathological phenotype in the first patient with FFI in the Netherlands, consisting of tau accumulations in several brain regions. A 57-year-old man presented with double vision and progressive memory loss. He was of Egyptian descent, but had lived in the Netherlands for 19 years. His family noted that he had become disoriented, confused and increasingly paranoid. For most of the day, he showed a tendency to fall asleep even during routine daily activities. However, while in this state, he experienced vivid dreaming and displayed frequent muscular jerks rather than resting as in normal slow-wave sleep. Later, he also suffered from a painful and itching sensation in both arms. In addition, he lost a significant amount of weight, despite an increased food intake. At neurological examination, 4 months after the onset of symptoms, the patient was disoriented in space and time, exhibited perseveration, mental confusion and an attention deficit. Spontaneous and evoked myoclonic jerks were observed in the hands, trunk and lower limbs. There was persistent hypertension, with loss of physiological nocturnal drop in blood pressure. The 14-3-3 test in cerebrospinal fluid was negative. Electroencephalography showed slowing of the global background rhythm, but no periodic sharp wave complexes were recorded. Polysomnography was abolished after 1.5 h due to confused behaviour. During this short recording there was excessive Rapid Eye Movement-sleep without atonia, sudden onset of slow-wave sleep with lack of K-complexes and sleep spindles and deep-sleep stages. Magnetic resonance imaging was hampered by movement artefacts. Over the next 2 months, his condition declined rapidly. He died at the age of 58 years, 7 months after the clinical onset of the disease. The family history indicated that his two sisters and possibly his father had been affected by a similar disorder (Figure 1). Permission was obtained for post mortem examination and tissues were retained for diagnosis and research. In the Netherlands, all autopsies are performed after informed consent has been obtained and ethical approval for research is automatically included for hospital autopsies. Samples of tissue from several brain regions were frozen at -80°C. Histopathological examination was performed on 5-mm-thick sections of formalin-fixed and paraffin-embedded brain tissue blocks, after decontamination for 1 h in 98% formic acid. Sections were taken from all areas of the cerebral cortex, the caudate nucleus, putamen, pallidum, hippocampal formation, including the transentorhinal and entorhinal regions, amygdala, Competing interests: none.

Hippocampal Calcification on Computed Tomography in Relation to Cognitive Decline in Memory Clinic Patients : A Case-Control Study

Background It was recently shown that calcification of the hippocampus can be detected on computed tomography (CT) images and these calcifications occur in up to 20% of people over 50 years of age. However, little is known about hippocampal calcification and its relation to cognition and cognitive decline. Therefore, the aim of this study was to (1) determine the prevalence of hippocampal calcification on CT in memory clinic patients controls, and (2) to assess its relation with cognitive decline. Methods 67 patients from a memory clinic (cases) were matched by age and gender to a control group. In both groups, hippocampal calcification was assessed by two raters on thin slice, non-contrast enhanced brain CT images. Calcifications were scored bilaterally on presence and severity (absent, mild, moderate, severe). Mini Mental State Exam (MMSE) score was determined in cases. Results Hippocampal calcification presence was significantly higher in cases (N = 26, 38.8%) compared to controls (N = 9, 13.4%) (P < .01) with an odds ratio of 4.40 (95%CI: 1.63–14.87). In cases, MMSE score was significantly lower in those with hippocampal calcification compared to those without (21.6 vs 24.5, p = .02). Conclusion In this case-control study we found significantly more hippocampal calcification in patients with cognitive decline as compared to controls. Furthermore, within the cases, MMSE score was significantly lower in those with hippocampal calcification.

Hippocampal calcification on brain CT: prevalence and risk factors in a cerebrovascular cohort

ObjectivesRecently, hippocampal calcification as observed on brain CT examinations was identified in over 20% of people over 50 years of age and a relation between hippocampal calcification and cognitive decline was shown. We determined the prevalence and investigated the vascular risk factors of hippocampal calcification in patients with cerebrovascular disease.MethodsHippocampal calcification was scored bilaterally on presence and severity on CT examinations in a cohort of 1130 patients with (suspected) acute ischaemic stroke. Multivariable logistic regression analysis, adjusting for age and gender as well as adjusting for multiple cardiovascular disease risk factors, was used to determine risk factors for hippocampal calcification.ResultsHippocampal calcification was present in 381 (34%) patients. Prevalence increased with age from 8% below 40 to 45% at 80 years and older. In multivariable logistic regression analysis, age per decile (OR 1.41 [95% CI 1.26–1.57], p < 0.01), hypertension (OR 0.74 [95% CI 0.56–0.99], p = 0.049), diabetes mellitus (OR 1.57 [95% CI 1.10–2.25], p = 0.01) and hyperlipidaemia (OR 1.63 [95% CI 1.20–2.22], p < 0.01) were significantly associated with hippocampal calcification.ConclusionsHippocampal calcification was a frequent finding on CT in this cohort of stroke patients and was independently positively associated with hyperlipidaemia and diabetes mellitus, suggesting an atherosclerotic origin.Key Points• Hippocampal calcification is prevalent in over 30% of cerebrovascular disease patients.• Prevalence increases from 8% below 40 to 45% over 80 years.• Hippocampal calcification is associated with cardiovascular risk factors hyperlipidaemia and diabetes mellitus.

Atypical Creutzfeldt-Jakob disease with PrP-amyloid plaques in white matter: molecular characterization and transmission to bank voles show the M1 strain signature

Amyloid plaques formed by abnormal prion protein (PrPSc) aggregates occur with low frequency in Creutzfeldt-Jakob disease, but represent a pathological hallmark of three relatively rare disease histotypes, namely variant CJD, sporadic CJDMV2K (methionine/valine at PRNP codon 129, PrPSc type 2 and kuru-type amyloid plaques) and iatrogenic CJDMMiK (MM at codon 129, PrPSc of intermediate type and kuru plaques). According to recent studies, however, PrP-amyloid plaques involving the subcortical and deep nuclei white matter may also rarely occur in CJDMM1 (MM at codon 129 and PrPSc type 1), the most common CJD histotype.To further characterize the phenotype of atypical CJDMM1 with white matter plaques (p-CJDMM1) and unravel the basis of amyloid plaque formation in such cases, we compared clinical and histopathological features and PrPSc physico-chemical properties between 5 p-CJDMM1 and 8 typical CJDMM1 brains lacking plaques. Furthermore, transmission properties after bioassay in two genetic lines of bank voles were also explored in the two groups.All 5 p-CJDMM1 cases hadxa0a disease duration longer than one year. Three cases were classified as sporadic CJDMM1, one as sporadic CJDMM1u2009+u20092C and one as genetic CJDE200K-MM1. Molecular mass, protease sensitivity and thermo-solubilization of PrPSc aggregates did not differ between p-CJDMM1 and classical CJDMM1 cases. Likewise, transmission properties such as incubation time, lesion profile and PrPSc properties in bank voles also matched in the two groups.The present data further define the clinical-pathologic phenotype of p-CJDMM1, definitely establish it as a distinctive CJD histotype and demonstrate that PrP-plaque formation in this histotype is not a strain-specific feature. Since cases lacking amyloid plaques may also manifest a prolonged (i.e. > than one year) disease course, unidentified, host-specific factors likely play a significant role, in addition to disease duration, in generating white matter PrP-amyloid plaques in p-CJDMM1.

Histological validation of calcifications in the human hippocampus as seen on computed tomography

Background Calcifications within the hippocampus were recently described for the first time on computed tomography (CT). These calcifications appeared in patients older than 50 years, the prevalence increases with age and they may be associated with cognitive decline. The aim of this study was to determine the histological basis (the presence, severity and location) of these CT-detected hippocampal calcifications of post-mortem brains. Methods CT scans of seven post-mortem brains were scored for the presence and severity (mild, moderate, severe) of hippocampal calcification. After this, samples from nine hippocampi (bilateral in two brains, unilateral in five brains) were stained with hematoxylin and eosin (HE) to indicate the cytoarchitecture, with Elastica van Gieson to analyse the elastic connective tissue of the vessel walls and with von Kossa for detection of calcium. Results In four brains (six hippocampi), calcifications were both found on CT and in corresponding histology. In three brains (three hippocampi), calcifications were absent on CT and corresponding histology. In histology, mild calcifications were located in the tail and severe calcifications involved the tail, body and sometimes the head of the hippocampus. The calcifications co-localised with precapillaries, capillaries and arteries of the molecular and granular layers of the dentate gyrus and the Cornu Ammonis 1. Conclusions In this study, calcifications of the hippocampus as seen on CT scans were histologically located in vascular structures of the tail, body and head of the hippocampus.

Additional file 8: of Proteomics analysis identifies new markers associated with capillary cerebral amyloid angiopathy in Alzheimerâ s disease

Figure S7. Immunoreactivity for COL6A2 is equally present in leptomeningeal vessels in control, AD and CAA tissue. (TIF 3794 kb)

Sporadic Fatal Insomnia in Europe: Phenotypic Features and Diagnostic Challenges: sFI in Europe

Comprehensively describe the phenotypic spectrum of sporadic fatal insomnia (sFI) to facilitate diagnosis and management of this rare and peculiar prion disorder.