New rare genetic variants in multiple sclerosis

In recent years, our understanding of genetic factors associated with multiple sclerosis (MS) has considerably increased as a result of new analytical approaches to genome-wide association studies, together with the large numbers of samples available through international collaborations. It is now clear that MS risk is multigenic, and that common variants (now numbering more than 150) contribute only a relatively small proportion to the overall heritability of MS. As a result, attention has once again turned to the possibility of identifying rare variants through a number of novel as well as more traditional methodologies. However, detecting effects of rare variants once again poses challenges of statistical power, and several different approaches can be applied to manage this issue, some of which are illustrated below. In this month’s Journal Club we review five recent publications that have employed large international cohorts, multiplex families, or candidate gene approaches to investigate rare genetic variants and their association with MS risk

A longitudinal model for disease progression was developed and applied to multiple sclerosis

OBJECTIVES: To develop a model of disease progression using multiple sclerosis (MS) as an exemplar. STUDY DESIGN AND SETTINGS: Two observational cohorts, the University of Wales MS (UoWMS), UK (1976), and British Columbia MS (BCMS) database, Canada (1980), with longitudinal disability data [the Expanded Disability Status Scale (EDSS)] were used; individuals potentially eligible for MS disease-modifying drugs treatments, but who were unexposed, were selected. Multilevel modeling was used to estimate the EDSS trajectory over time in one data set and validated in the other; challenges addressed included the choice and function of time axis, complex observation-level variation, adjustments for MS relapses, and autocorrelation. RESULTS: The best-fitting model for the UoWMS cohort (404 individuals, and 2,290 EDSS observations) included a nonlinear function of time since onset. Measurement error decreased over time and ad hoc methods reduced autocorrelation and the effect of relapse. Replication within the BCMS cohort (978 individuals and 7,335 EDSS observations) led to a model with similar time (years) coefficients, time [0.22 (95% confidence interval {CI}: 0.19, 0.26), 0.16 (95% CI: 0.10, 0.22)] and log time [-0.13 (95% CI: -0.39, 0.14), -0.15 (95% CI: -0.70, 0.40)] for BCMS and UoWMS, respectively. CONCLUSION: It is possible to develop robust models of disability progression for chronic disease. However, explicit validation is important given the complex methodological challenges face

How common is truly benign MS in a UK population?

Objectives The prevalence and definition of benign multiple sclerosis (BMS) remain controversial. Most definitions are based on the Expanded Disability Status Scale (EDSS), not encompassing the wider impact of disease. The explanation for favourable outcomes remains unclear. We aim to provide a detailed characterisation of patients with low EDSS scores at long disease durations. Methods We screened a population-based registry containing 3062 people with MS to identify individuals with unlimited walking ability at disease durations >15 years. A representative cohort underwent detailed clinical assessment and classified as having BMS according to EDSS score <3, no significant fatigue, mood disturbance, cognitive impairment or disrupted employment, and had not received a disease-modifying therapy. We determined patient-reported perceptions of MS status and made comparisons with EDSS-based definitions. Results Of 1049 patients with disease duration of >15 years, 200 (19.1%) had most recent EDSS score <4.0. Detailed contemporary clinical assessment of a representative sample of 60 of these patients revealed 48 (80%) had an EDSS score of <4.0, 35 (58%) <3.0 and 16 (27%) <2.0. Only nine (15%) fulfilled our criteria for BMS; impaired cognition (57%) and effects on employment (52%) the most common causes for exclusion. Meanwhile, 33/60 (69%) patients considered their disease benign. Population frequency for BMS was estimated at 2.9% (95% CI 2.0 to 4.1). Conclusions Comprehensive assessment reveals a small minority of people with MS who appear genuinely benign after 15 years. Study of such individuals may uncover insights about disease pathogenesis. However, discrepancy between patient perception and clinician perception of BMS undermines use of the term ‘benign’ in clinical settings

Serum neurofilament-light concentration and real-world outcome in MS

Background Prognostication in multiple sclerosis (MS) remains challenging. Biomarkers capable of providing this information at diagnosis would be valuable in shaping therapeutic decisions. Measurement of neurofilament light (NfL) has shown promise in predicting clinical outcomes in established MS, but its ability to predict outcomes in real-world cohorts at diagnosis requires further validation. Methods We used linear regression to evaluate the relationship between serum NfL (sNfL), measured at the time of diagnosis with short-term (1-year) and medium-term (5-year) clinical outcomes in 164 people with MS from a real-world, population-based cohort. Cox proportional hazards regression was used to analyse the association between sNfL and subsequent hazard of relapse or sustained accumulation of disability (SAD). Analyses were adjusted for age and disease-modifying treatment (DMT). Results sNfL concentration at diagnosis was modestly associated with baseline EDSS score (β = 0.272, 95% CI 0.051 to 0.494, p = 0.016). However, no significant associations were found between baseline sNfL and odds of relapse at 12-months, 5-year EDSS change, or the hazard of relapse or SAD over 5 years follow-up. Dichotomising baseline sNfL according to the median sNfL did not change these findings. Conclusions sNfL appears to be of limited clinical utility in predicting future irreversible neurological disability in a largely untreated real-world population, and remains insufficiently validated to shape treatment decisions at the time of diagnosis. Further studies may be needed for sNfL to be considered as a prognostic marker in the MS clinic. However the masking effect of DMTs on the natural disease trajectory will continue to pose challenges

Opal (Zn/Si) ratios as a nearshore geochemical proxy in coastal Antarctica

Author Posting. © American Geophysical Union, 2008. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Paleoceanography 23 (2008): PA2218, doi:10.1029/2007PA001576.During the last 50 years, the Antarctic Peninsula has experienced rapid warming with associated retreat of 87% of marine and tidewater glacier fronts. Accelerated glacial retreat and iceberg calving may have a significant impact on the freshwater and nutrient supply to the phytoplankton communities of the highly productive coastal regions. However, commonly used biogenic carbonate proxies for nutrient and salinity conditions are not preserved in sediments from coastal Antarctica. Here we describe a method for the measurement of zinc to silicon ratios in diatom opal, (Zn/Si)opal, which is a potential archive in Antarctic marine sediments. A core top calibration from the West Antarctic Peninsula shows (Zn/Si)opal is a proxy for mixed layer salinity. We present down-core (Zn/Si)opal paleosalinity records from two rapidly accumulating sites taken from nearshore environments off the West Antarctic Peninsula which show an increase in meltwater input in recent decades. Our records show that the recent melting in this region is unprecedented for over 120 years.The work was funded as part of NERC Antarctic Funding Initiative AFI4– 02. K.R.H. is funded by NERC grant NER/S/A/2004/12390

The Eighth Data Release of the Sloan Digital Sky Survey: First Data from SDSS-III

The Sloan Digital Sky Survey (SDSS) started a new phase in August 2008, with new instrumentation and new surveys focused on Galactic structure and chemical evolution, measurements of the baryon oscillation feature in the clustering of galaxies and the quasar Ly alpha forest, and a radial velocity search for planets around ~8000 stars. This paper describes the first data release of SDSS-III (and the eighth counting from the beginning of the SDSS). The release includes five-band imaging of roughly 5200 deg^2 in the Southern Galactic Cap, bringing the total footprint of the SDSS imaging to 14,555 deg^2, or over a third of the Celestial Sphere. All the imaging data have been reprocessed with an improved sky-subtraction algorithm and a final, self-consistent photometric recalibration and flat-field determination. This release also includes all data from the second phase of the Sloan Extension for Galactic Understanding and Evolution (SEGUE-2), consisting of spectroscopy of approximately 118,000 stars at both high and low Galactic latitudes. All the more than half a million stellar spectra obtained with the SDSS spectrograph have been reprocessed through an improved stellar parameters pipeline, which has better determination of metallicity for high metallicity stars.Comment: Astrophysical Journal Supplements, in press (minor updates from submitted version

Adaptation interventions and their effect on vulnerability in developing countries: Help, hindrance or irrelevance?

This paper critically reviews the outcomes of internationally-funded interventions aimed at climate change adaptation and vulnerability reduction. It highlights how some interventions inadvertently reinforce, redistribute or create new sources of vulnerability. Four mechanisms drive these maladaptive outcomes: (i) shallow understanding of the vulnerability context; (ii) inequitable stakeholder participation in both design and implementation; (iii) a retrofitting of adaptation into existing development agendas; and (iv) a lack of critical engagement with how ‘adaptation success’ is defined. Emerging literature shows potential avenues for overcoming the current failure of adaptation interventions to reduce vulnerability: first, shifting the terms of engagement between adaptation practitioners and the local populations participating in adaptation interventions; and second, expanding the understanding of ‘local’ vulnerability to encompass global contexts and drivers of vulnerability. An important lesson from past adaptation interventions is that within current adaptation cum development paradigms, inequitable terms of engagement with ‘vulnerable’ populations are reproduced and the multi-scalar processes driving vulnerability remain largely ignored. In particular, instead of designing projects to change the practices of marginalised populations, learning processes within organisations and with marginalised populations must be placed at the centre of adaptation objectives. We pose the question of whether scholarship and practice need to take a post-adaptation turn akin to post-development, by seeking a pluralism of ideas about adaptation while critically interrogating how these ideas form part of the politics of adaptation and potentially the processes (re)producing vulnerability. We caution that unless the politics of framing and of scale are explicitly tackled, transformational interventions risk having even more adverse effects on marginalised populations than current adaptation

Non-motor phenotypic subgroups in adult-onset idiopathic, isolated, focal cervical dystonia

Background: Non-motor symptoms are well established phenotypic components of adult-onset idiopathic, isolated, focal cervical dystonia (AOIFCD). However, improved understanding of their clinical heterogeneity is needed to better target therapeutic intervention. Here, we examine non-motor phenotypic features to identify possible AOIFCD subgroups. Methods: Participants diagnosed with AOIFCD were recruited via specialist neurology clinics (dystonia wales: n = 114, dystonia coalition: n = 183). Non-motor assessment included psychiatric symptoms, pain, sleep disturbance, and quality of life, assessed using self-completed questionnaires or face-to-face assessment. Both cohorts were analyzed independently using Cluster, and Bayesian multiple mixed model phenotype analyses to investigate the relationship between non-motor symptoms and determine evidence of phenotypic subgroups. Results: Independent cluster analysis of the two cohorts suggests two predominant phenotypic subgroups, one consisting of approximately a third of participants in both cohorts, experiencing increased levels of depression, anxiety, sleep impairment, and pain catastrophizing, as well as, decreased quality of life. The Bayesian approach reinforced this with the primary axis, which explained the majority of the variance, in each cohort being associated with psychiatric symptomology, and also sleep impairment and pain catastrophizing in the Dystonia Wales cohort. Conclusions: Non-motor symptoms accompanying AOIFCD parse into two predominant phenotypic sub-groups, with differences in psychiatric symptoms, pain catastrophizing, sleep quality, and quality of life. Improved understanding of these symptom groups will enable better targeted pathophysiological investigation and future therapeutic intervention