PRKAR1B mutation associated with a new neurodegenerative disorder with unique pathology.

Pathological accumulation of intermediate filaments can be observed in neurodegenerative disorders, such as Alzheimer's disease, frontotemporal dementia and Parkinson's disease, and is also characteristic of neuronal intermediate filament inclusion disease. Intermediate filaments type IV include three neurofilament proteins (light, medium and heavy molecular weight neurofilament subunits) and α-internexin. The phosphorylation of intermediate filament proteins contributes to axonal growth, and is regulated by protein kinase A. Here we describe a family with a novel late-onset neurodegenerative disorder presenting with dementia and/or parkinsonism in 12 affected individuals. The disorder is characterized by a unique neuropathological phenotype displaying abundant neuronal inclusions by haematoxylin and eosin staining throughout the brain with immunoreactivity for intermediate filaments. Combining linkage analysis, exome sequencing and proteomics analysis, we identified a heterozygous c.149T>G (p.Leu50Arg) missense mutation in the gene encoding the protein kinase A type I-beta regulatory subunit (PRKAR1B). The pathogenicity of the mutation is supported by segregation in the family, absence in variant databases, and the specific accumulation of PRKAR1B in the inclusions in our cases associated with a specific biochemical pattern of PRKAR1B. Screening of PRKAR1B in 138 patients with Parkinson's disease and 56 patients with frontotemporal dementia did not identify additional novel pathogenic mutations. Our findings link a pathogenic PRKAR1B mutation to a novel hereditary neurodegenerative disorder and suggest an altered protein kinase A function through a reduced binding of the regulatory subunit to the A-kinase anchoring protein and the catalytic subunit of protein kinase A, which might result in subcellular dislocalization of the catalytic subunit and hyperphosphorylation of intermediate filaments.

Accuracy of the National Institute for Neurological Disorders and Stroke/Society for Progressive Supranuclear Palsy and neuroprotection and natural history in Parkinson plus syndromes criteria for the diagnosis of progressive supranuclear palsy.

Autopsy is the diagnostic gold standard for progressive supranuclear palsy (PSP). The National Institute of Neurological Disorders and Stroke and Society for Progressive Supranuclear Palsy (NINDS-SPSP) criteria for the clinical diagnosis of "probable" PSP are thought to possess high specificity and low sensitivity. The NINDS-SPSP criteria for "possible" PSP are considered to increase sensitivity at the expense of specificity. The Neuroprotection and Natural History in Parkinson Plus Syndromes (NNIPPS) criteria are intended to improve sensitivity while maintaining high specificity. The aim of this study was to conduct a clinicopathological evaluation of the NINDS-SPSP and NNIPPS criteria in tertiary neurological centers. Defined clinical features and their year of onset were recorded by chart review in neuropathologically diagnosed patients with PSP, Parkinsons's disease (PD), MSA parkinsonism and corticobasal degeneration from four European brain banks. Fulfillment of the clinical diagnostic criteria was verified for each year after disease onset and for the final antemortem record. We analyzed 98 PSP patients and 46 disease controls. The NINDS-SPSP "probable" criteria yielded shorter time to diagnosis, slightly higher specificity and positive predictive value (PPV), and similar sensitivity, compared with the NNIPPS criteria. Unexpectedly, the NINDS-SPSP "possible" criteria yielded the lowest sensitivity, specificity, and PPV. A combination of NINDS-SPSP possible and probable criteria yielded the highest sensitivity. We suggest that the NINDS-SPSP probable criteria might be preferred for recruitment of patients for clinical trials, where an early and specific diagnosis is important. For routine clinical care, where high sensitivity is crucial, a combination of NINDS possible and probable criteria might be preferred.

Midcingulate involvement in progressive supranuclear palsy and tau positive frontotemporal dementia.

BACKGROUND: Progressive supranuclear palsy (PSP) patients often exhibit cognitive decline and behavioural changes during the disease course. In a subset, these symptoms may be the presenting manifestation and can be similar to those in frontotemporal dementia (FTD). However, correlation studies between quantitative imaging measures and detailed neuropsychological assessment are scarce. The aim of this study was to investigate the functional role of affected brain regions in cognition in PSP compared with controls and subsequently examine these regions in FTD patients with known tau pathology (FTD tau). METHODS: 21 PSP patients, 27 healthy controls and 11 FTD tau patients were enrolled. All participants underwent neuropsychological testing and technetium-99m-hexamethyl-propylenamine-oxime single photon emission CT. Regression slope analyses were performed in statistical parametric mapping to find significant associations between neuropsychological test results and brain perfusion. RESULTS: PSP patients showed hypoperfusion in the midcingulate cortex (MCC) of which the posterior part correlated with Stroop III and Weigl. In FTD tau patients, MCC involvement was located more anterior and correlated with Stroop III and Wisconsin Card Sorting Test concepts. The degree of hypoperfusion in the anterior cortex and MCC in the disorders differed in the subgenual anterior cingulate cortex only. CONCLUSIONS: The posterior part of the MCC is prominently involved in the neurodegenerative process of PSP, and the severity of its hypoperfusion correlated with the extent of executive dysfunction. In FTD tau, this cognitive domain was associated with anterior MCC involvement. The degree of hypoperfusion in these regions did not differ between PSP and FTD tau. These observations provide insight into the role of the cingulate cortex in cognitive dysfunction in these neurodegenerative disorders and warrant further investigations.

Survival in progressive supranuclear palsy and frontotemporal dementia.

OBJECTIVE: To compare survival and to identify prognostic predictors for progressive supranuclear palsy and frontotemporal dementia. BACKGROUND: Progressive supranuclear palsy (PSP) and frontotemporal dementia (FTD) are related disorders. Homozygosity for H1 haplotype is associated with PSP, whereas several MAPT mutations have been identified in FTLD-tau. Survival duration probably reflects underlying pathophysiology or disease. METHODS: Patients with PSP and FTD were recruited by nationwide referral. Survival of 354 FTD patients was compared with that of 197 PSP patients. Cox regression analysis was performed to identify prognostic predictors. FTLD-tau was defined as Pick disease and FTDP-17 with MAPT mutations. Semiquantitative evaluation of tau-positive pathology was performed on all pathologically proven cases. RESULTS: The median survival of PSP patients (8.0 years; 95% CI 7.3 to 8.7) was significantly shorter than that of FTD patients (9.9 years; 95% CI 9.2 to 10.6). Corrected for demographic differences, PSP patients were still significantly more at risk of dying than FTD patients. In PSP, male gender, older onset-age and higher PSP Rating Scale score were identified as independent predictors for shorter survival, whereas in FTD a positive family history and an older onset-age were associated with a poor prognosis. The difference in hazard rate was even more pronounced when comparing pathologically proven cases of PSP with FTLD-tau. CONCLUSION: Survival of PSP patients is shorter than that of FTD patients, and probably reflects a more aggressive disease process in PSP. Independent predictors of shorter survival in PSP were male gender, older onset-age and higher PSP rating scale score, whereas in FTD a positive family history and higher onset-age were predictors for worse prognosis.

Multireceptor fingerprints in progressive supranuclear palsy.

BACKGROUND: Progressive supranuclear palsy (PSP) with a frontal presentation, characterized by cognitive deficits and behavioral changes, has been recognized as an early clinical picture, distinct from the classical so-called Richardson and parkinsonism presentations. The midcingulate cortex is associated with executive and attention tasks and has consistently been found to be impaired in imaging studies of patients with PSP. The aim of the present study was to determine alterations in neurotransmission underlying the pathophysiology of PSP, as well as their significance for clinically identifiable PSP subgroups. METHODS: In vitro receptor autoradiography was used to quantify densities of 20 different receptors in the caudate nucleus and midcingulate area 24' of patients with PSP (n = 16) and age- and sex-matched control subjects (n = 14). RESULTS: Densities of γ-aminobutyric acid type B, peripheral benzodiazepine, serotonin receptor type 2, and N-methyl-D-aspartate receptors were significantly higher in area 24' of patients with PSP, where tau impairment was stronger than in the caudate nucleus. Kainate and nicotinic cholinergic receptor densities were significantly lower, and adenosine receptor type 1 (A1) receptors significantly higher, in the caudate nucleus of patients with PSP. Receptor fingerprints also segregated PSP subgroups when clinical parameters such as occurrence of frontal presentation and tau pathology severity were taken into consideration. CONCLUSIONS: We demonstrate, for the first time to our knowledge, that kainate and A1 receptors are altered in PSP and that clinically identifiable PSP subgroups differ at the neurochemical level. Numerous receptors were altered in the midcingulate cortex, further suggesting that it may prove to be a key region in PSP. Finally, we add to the evidence that nondopaminergic systems play a role in the pathophysiology of PSP, thus highlighting potential novel treatment strategies.

Symmetrical corticobasal syndrome caused by a novel C.314dup progranulin mutation.

Corticobasal syndrome (CBS) is characterised by asymmetrical parkinsonism and cognitive impairment. The underlying pathology varies between corticobasal degeneration, progressive supranuclear palsy, Alzheimer's disease, Creutzfeldt-Jakob disease and frontotemporal lobar degeneration sometimes in association with GRN mutations. A 61-year-old male underwent neurological examination, neuropsychological assessment, MRI, and HMPAO-SPECT at our medical centre. After his death at the age of 63, brain autopsy, genetic screening and mRNA expression analysis were performed. The patient presented with slow progressive walking disabilities, non-fluent language problems, behavioural changes and forgetfulness. His family history was negative. He had primitive reflexes, rigidity of his arms and postural instability. Later in the disease course he developed dystonia of his left leg, pathological crying, mutism and dysphagia. Neuropsychological assessment revealed prominent ideomotor and ideational apraxia, executive dysfunction, non-fluent aphasia and memory deficits. Neuroimaging showed symmetrical predominant frontoparietal atrophy and hypoperfusion. Frontotemporal lobar degeneration (FTLD)-TDP type 3 pathology was found at autopsy. GRN sequencing revealed a novel frameshift mutation c.314dup, p.Cys105fs and GRN mRNA levels showed a 50% decrease. We found a novel GRN mutation in a patient with an atypical (CBS) presentation with symmetric neuroimaging findings. GRN mutations are an important cause of CBS associated with FTLD-TDP type 3 pathology, sometimes in sporadic cases. Screening for GRN mutations should also be considered in CBS patients without a positive family history.

Frequency of ubiquitin and FUS-positive, TDP-43-negative frontotemporal lobar degeneration.

Frontotemporal lobar degeneration (FTLD) is a clinically, genetically and pathologically heterogeneous disorder. Within FTLD with ubiquitin-positive inclusions (FTLD-U), a new pathological subtype named FTLD-FUS was recently found with fused in sarcoma (FUS) positive, TDP-43-negative inclusions, and striking atrophy of the caudate nucleus. The aim of this study was to determine the frequency of FTLD-FUS in our pathological FTLD series, and to describe the clinical, neuroimaging and neuropathological features of FTLD-FUS, especially caudate atrophy. Demographic and clinical data collected prospectively from 387 patients with frontotemporal dementia (FTD) yielded 74 brain specimens. Immunostaining was carried out using a panel of antibodies, including AT-8, ubiquitin, p62, FUS, and TDP-43. Cortical and caudate atrophy on MRI (n = 136) was rated as normal, mild-moderate or severe. Of the 37 FTLD-U cases, 33 were reclassified as FTLD-TDP and four (0.11, 95%: 0.00-0.21) as FTLD-FUS, with ubiquitin and FUS-positive, p62 and TDP-43-negative neuronal intranuclear inclusions (NII). All four FTLD-FUS cases had a negative family history, behavioural variant FTD (bvFTD), and three had an age at onset