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Novel homozygous splicing mutations in ARL2BP cause autosomal recessive retinitis pigmentosa.
Purpose: Mutations in ARL2BP, encoding ADP-ribosylation factor-like 2 binding protein, have recently been implicated as a cause of autosomal recessive retinitis pigmentosa (arRP), with three homozygous variants identified to date. In this study, we performed next-generation sequencing to reveal additional arRP cases associated with ARL2BP variants. Methods: Whole-genome sequencing (WGS) or whole-exome sequencing (WES) was performed in 1,051 unrelated individuals recruited for the UK Inherited Retinal Disease Consortium and NIHR-BioResource Rare Diseases research studies. Sanger sequencing was used to validate the next-generation sequencing data, and reverse transcriptase (RT)-PCR analysis was performed on RNA extracted from blood from affected individuals to test for altered splicing of ARL2BP. Detailed phenotyping was performed, including clinical evaluation, electroretinography, fundus photography, fundus autofluorescence imaging, and spectral-domain optical coherence tomography. Results: Homozygous variants in ARL2BP (NM_012106.3) were identified in two unrelated individuals with RP. The variants, c.207+1G>A and c.390+5G>A, at conserved splice donor sites for intron 3 and intron 5, respectively, were predicted to alter the pre-mRNA splicing of ARL2BP. RT-PCR spanning the affected introns revealed that both variants caused abnormal splicing of ARL2BP in samples from affected individuals. Conclusions: This study identified two homozygous variants in ARL2BP as a rare cause of arRP. Further studies are required to define the underlying disease mechanism causing retinal degeneration as a result of mutations in ARL2BP and any phenotype-genotype correlation associated with residual levels of the wild-type transcript.
Renal replacement anticoagulant management: Protocol and analysis plan for an observational comparative effectiveness study of linked data sources
© The Intensive Care Society 2020. Acute kidney injury is common in critical illness. In patients with severe acute kidney injury, renal replacement therapy is needed to prevent harm from metabolic and electrolyte disturbances and fluid overload. In the UK, continuous renal replacement therapy (CRRT) is the preferred modality, which requires anticoagulation. Over the last decade, conventional systemic heparin anticoagulation has started being replaced by regional citrate anticoagulation for CRRT, which is now used in approximately 50% of ICUs. This shift towards regional citrate anticoagulation for CRRT is occurring with little evidence of safety or longer term effectiveness. Renal replacement anticoagulant management (RRAM) is an observational comparative effectiveness study, utilising existing data sources to address the clinical and cost-effectiveness of the change to regional citrate anticoagulation for CRRT in UK ICUs. The study will use data from approximately 85,000 patients who were treated in adult, general ICUs participating in the case mix programme national clinical audit between 1 April 2009 and 31 March 2017. A survey of health service providers’ anticoagulation practices will be combined with treatment and hospital outcome data from the case mix programme and linked with long-term outcomes from the Civil Registrations (deaths), Hospital Episodes Statistics for England, Patient Episodes Data for Wales, and the UK Renal Registry datasets. The primary clinical effectiveness outcome is all-cause mortality at 90-days. The study will incorporate an economic evaluation with micro-costing of both regional citrate anticoagulation and systemic heparin anticoagulation. Study registration: NCT03545750
Improved fibre dispersion estimation using b-tensor encoding.
Measuring fibre dispersion in white matter with diffusion magnetic resonance imaging (MRI) is limited by an inherent degeneracy between fibre dispersion and microscopic diffusion anisotropy (i.e., the diffusion anisotropy expected for a single fibre orientation). This means that estimates of fibre dispersion rely on strong assumptions, such as constant microscopic anisotropy throughout the white matter or specific biophysical models. Here we present a simple approach for resolving this degeneracy using measurements that combine linear (conventional) and spherical tensor diffusion encoding. To test the accuracy of the fibre dispersion when our microstructural model is only an approximation of the true tissue structure, we simulate multi-compartment data and fit this with a single-compartment model. For such overly simplistic tissue assumptions, we show that the bias in fibre dispersion is greatly reduced (∼5x) for single-shell linear and spherical tensor encoding data compared with single-shell or multi-shell conventional data. In in-vivo data we find a consistent estimate of fibre dispersion as we reduce the b-value from 3 to 1.5 ms/μm2, increase the repetition time, increase the echo time, or increase the diffusion time. We conclude that the addition of spherical tensor encoded data to conventional linear tensor encoding data greatly reduces the sensitivity of the estimated fibre dispersion to the model assumptions of the tissue microstructure.
APOE-ε4 Genotype and Dementia Before and After Transient Ischemic Attack and Stroke: Population-Based Cohort Study.
Background and Purpose- APOE-ε4 genotype is a risk factor for sporadic Alzheimer disease and reduced recovery from brain injury. Since data on APOE genotype and dementia associated with transient ischemic attack/stroke are sparse, we determined the associations in a longitudinal population-based cohort. Methods- All patients with transient ischemic attack or stroke (2002-2012) in a defined population of 92 728 OxVASC (Oxford Vascular Study) had follow-up to 5-years. Pre-event and incident postevent dementia were ascertained through direct patient assessment and follow-up, supplemented by review of hospital/primary care records. Associations between pre- and post-event dementia and APOE genotype (ε4/ε4-homozygous and ε4/ε3-heterozygous versus ε3/ε3) were examined using logistic regression and Cox regression models, respectively, adjusted for age, sex, education, cerebrovascular burden (stroke severity, prior stroke, white matter disease), diabetes mellitus, and dysphasia. Results- Among 1767 genotyped patients (mean/SD age, 73.0/13.0 years, 901 [51%] male, 602 [34%] transient ischemic attack), 1058 (59.9%) were APOE-ε3/ε3, 403 (22.8%) were ε4/ε3 and 30 (1.7%) were ε4-homozygous. Homozygosity was associated with both pre-event (adjusted odds ratio, 5.81 [95% CI, 1.93-17.48]; P=0.002) and postevent dementia (adjusted hazard ratio, 3.64 [95% CI, 1.90-7.00]; P<0.0001). Association with postevent dementia was maintained after further adjustment for baseline cognitive impairment (hazard ratio, 2.41 [95% CI, 1.19-4.89]; P=0.01). There were no associations overall between ε4/ε3 and pre-event dementia (adjusted odds ratio, 1.47 [95% CI, 0.88-2.45]; P=0.14) or postevent dementia (hazard ratio, 1.11 [95% CI, 0.84-1.48]; P=0.47). Conclusions- In patients with transient ischemic attack and stroke, APOE-ε4 homozygosity was associated with both pre- and post-event dementia. Associations were independent of cerebrovascular burden and may be mediated through increased neurodegenerative pathology or vulnerability to injury.
Global Stroke Statistics 2019.
BACKGROUND:Data on stroke epidemiology and availability of hospital-based stroke services around the world are important for guiding policy decisions and healthcare planning. AIMS:To provide the most current incidence, mortality and case-fatality data on stroke and describe current availability of stroke units around the world by country. METHODS:We searched multiple databases (based on our existing search strategy) to identify new original manuscripts and review articles published between 1 June 2016 and 31 October 2018 that met the ideal criteria for data on stroke incidence and case-fatality. For data on the availability of hospital-based stroke services, we searched PubMed for all literature published up until 31 June 2018. We further screened reference lists, citation history of manuscripts and gray literature for this information. Mortality codes for International Classification of Diseases-9 and International Classification of Diseases-10 were extracted from the World Health Organization mortality database for each country providing these data. Population denominators were obtained from the World Health Organization, and when these were unavailable within a two-year period of mortality data, population denominators within a two-year period were obtained from the United Nations. Using country-specific population denominators and the most recent years of mortality data available for each country, we calculated both the crude mortality from stroke and mortality adjusted to the World Health Organization world population. RESULTS:Since our last report in 2017, there were two countries with new incidence studies, China (n = 1) and India (n = 2) that met the ideal criteria. New data on case-fatality were found for Estonia and India. The most current mortality data were available for the year 2015 (39 countries), 2016 (43 countries), and 2017 (7 countries). No new data on mortality were available for six countries. Availability of stroke units was noted for 63 countries, and the proportion of patients treated in stroke units was reported for 35/63 countries. CONCLUSION:Up-to-date data on stroke incidence, case-fatality, and mortality statistics provide evidence of variation among countries and changing magnitudes of burden among high and low-middle income countries. Reporting of hospital-based stroke units remains limited and should be encouraged.