Novel plasma and brain proteins that are implicated in multiple sclerosis.

Understanding how variations in the plasma and brain proteome contribute to multiple sclerosis susceptibility can provide important insights to guide drug repurposing and therapeutic development for the disease. However, the role of genetically predicted protein abundance in multiple sclerosis remains largely unknown. Integrating plasma proteomics (n = 3301) and brain proteomics (n = 376 discovery; n = 152 replication) into multiple sclerosis genome-wide association studies (n = 14 802 cases and 26 703 controls), we employed summary-based methods to identify candidate proteins involved in multiple sclerosis susceptibility. Next, we evaluated associations of the corresponding genes with multiple sclerosis at tissue-level using large gene expression quantitative trait data from whole-blood (n = 31 684) and brain (n = 1194) tissue. Further, to assess transcriptional profiles for candidate proteins at cell-level, we examined gene expression patterns in immune cell types (Dataset 1: n = 73 cases and 97 controls; Dataset 2: n = 31 cases and 31 controls) for identified plasma proteins, and in brain cell types (Dataset 1: n = 4 cases and 5 controls; Dataset 2: n = 5 cases and 3 controls) for identified brain proteins. In a longitudinal multiple sclerosis cohort (n = 203 cases followed up to 15 years), we also assessed the corresponding gene-level associations with the outcome of disability worsening. We identified 39 novel proteins associated with multiple sclerosis risk. Based on five identified plasma proteins, four available corresponding gene candidates showed consistent associations with multiple sclerosis risk in whole-blood, and we found TAPBPL upregulation in multiple sclerosis B cells, CD8+ T cells and natural killer cells compared with controls. Among the 34 candidate brain proteins, 18 were replicated in a smaller cohort and 14 of 21 available corresponding gene candidates also showed consistent associations with multiple sclerosis risk in brain tissue. In cell-specific analysis, six identified brain candidates showed consistent differential gene expression in neuron and oligodendrocyte cell clusters. Based on the 39 protein-coding genes, we found 23 genes that were associated with disability worsening in multiple sclerosis cases. The findings present a set of candidate protein biomarkers for multiple sclerosis, reinforced by high concordance in downstream transcriptomics findings at tissue-level. This study also highlights the heterogeneity of cell-specific transcriptional profiles for the identified proteins and that numerous candidates were also implicated in disease progression. Together, these findings can serve as an important anchor for future studies of disease mechanisms and therapeutic development.

Rapid and efficient cataract gene evaluation in F0 zebrafish using CRISPR-Cas9 ribonucleoprotein complexes.

Cataract is the leading cause of blindness worldwide. Congenital or paediatric cataract can result in permanent visual impairment or blindness even with best attempts at treatment. A significant proportion of paediatric cataract has a genetic cause. Therefore, identifying the genes that lead to cataract formation is essential for understanding the pathological process of inherited paediatric cataract as well as to the development of new therapies. Despite clear progress in genomics technologies, verification of the biological effects of newly identified candidate genes and variants is still challenging. Here, we provide a step-by-step pipeline to evaluate cataract candidate genes in F0 zebrafish using CRISPR-Cas9 ribonucleoprotein complexes (RNP). Detailed descriptions of CRISPR-Cas9 RNP design and formulation, microinjection, optimization of CRISPR-Cas9 RNP reagent dose and delivery route, editing efficacy analysis as well as cataract formation evaluation are included. Following this protocol, any cataract candidates can be readily and efficiently evaluated within 2 weeks using basic laboratory supplies.

Utilising multi-large omics data to elucidate biological mechanisms within multiple sclerosis genetic susceptibility loci.

BACKGROUND: Genome-wide association studies (GWAS) have succeeded in identifying over 200 susceptibility loci for multiple sclerosis (MS). However, the potential functional variants and the mechanisms by which these loci affect MS risk remain largely unexplained. OBJECTIVES: We used summary data-based Mendelian randomisation to prioritise risk genes and infer potential biological mechanisms for MS risk loci. METHODS: The data used consisted of DNA methylation (n = 1980) QTL (mQTL) and gene expression (n = 31,684) QTL (eQTL) derived from whole blood as well as MS GWAS summary statistics (14,802 cases, 26,703 controls). The findings were further evaluated using data derived from independent brain mQTL (n = 1160) and eQTL (n = 1194). RESULTS: In whole blood, we identified two independent genomic loci (lincRNA: RP11-326C3.13 and TNFSF14) with consistent genome-wide significant pleiotropic associations across different omics layers. In brain tissue, a similar effect for the RP11-326C3.13 locus was observed but not for TNFSF14, indicating a potential tissue-specific effect for the TNFSF14 locus. CONCLUSION: We provide in silico evidence for the putative biological mechanisms by which the identified DNA methylation sites and target genes are functionally relevant to MS development in different tissues. Future research targeting these genes and DNA methylation sites will determine their roles in the pathophysiology of MS.

The voltage-gated calcium channel CaV1.2 promotes adult oligodendrocyte progenitor cell survival in the mouse corpus callosum but not motor cortex.

Throughout life, oligodendrocyte progenitor cells (OPCs) proliferate and differentiate into myelinating oligodendrocytes. OPCs express cell surface receptors and channels that allow them to detect and respond to neuronal activity, including voltage-gated calcium channel (VGCC)s. The major L-type VGCC expressed by developmental OPCs, CaV1.2, regulates their differentiation. However, it is unclear whether CaV1.2 similarly influences OPC behavior in the healthy adult central nervous system (CNS). To examine the role of CaV1.2 in adulthood, we conditionally deleted this channel from OPCs by administering tamoxifen to P60 Cacna1c fl/fl (control) and Pdgfrα-CreER:: Cacna1c fl/fl (CaV1.2-deleted) mice. Whole cell patch clamp analysis revealed that CaV1.2 deletion reduced L-type voltage-gated calcium entry into adult OPCs by ~60%, confirming that it remains the major L-type VGCC expressed by OPCs in adulthood. The conditional deletion of CaV1.2 from adult OPCs significantly increased their proliferation but did not affect the number of new oligodendrocytes produced or influence the length or number of internodes they elaborated. Unexpectedly, CaV1.2 deletion resulted in the dramatic loss of OPCs from the corpus callosum, such that 7 days after tamoxifen administration CaV1.2-deleted mice had an OPC density ~42% that of control mice. OPC density recovered within 2 weeks of CaV1.2 deletion, as the lost OPCs were replaced by surviving CaV1.2-deleted OPCs. As OPC density was not affected in the motor cortex or spinal cord, we conclude that calcium entry through CaV1.2 is a critical survival signal for a subpopulation of callosal OPCs but not for all OPCs in the mature CNS.

Rediscovering the value of families for psychiatric genetics research.

As it is likely that both common and rare genetic variation are important for complex disease risk, studies that examine the full range of the allelic frequency distribution should be utilized to dissect the genetic influences on mental illness. The rate limiting factor for inferring an association between a variant and a phenotype is inevitably the total number of copies of the minor allele captured in the studied sample. For rare variation, with minor allele frequencies of 0.5% or less, very large samples of unrelated individuals are necessary to unambiguously associate a locus with an illness. Unfortunately, such large samples are often cost prohibitive. However, by using alternative analytic strategies and studying related individuals, particularly those from large multiplex families, it is possible to reduce the required sample size while maintaining statistical power. We contend that using whole genome sequence (WGS) in extended pedigrees provides a cost-effective strategy for psychiatric gene mapping that complements common variant approaches and WGS in unrelated individuals. This was our impetus for forming the "Pedigree-Based Whole Genome Sequencing of Affective and Psychotic Disorders" consortium. In this review, we provide a rationale for the use of WGS with pedigrees in modern psychiatric genetics research. We begin with a focused review of the current literature, followed by a short history of family-based research in psychiatry. Next, we describe several advantages of pedigrees for WGS research, including power estimates, methods for studying the environment, and endophenotypes. We conclude with a brief description of our consortium and its goals.

Lipid-related genetic polymorphisms significantly modulate the association between lipids and disability progression in multiple sclerosis.

OBJECTIVE: To investigate whether lipid-related or body mass index (BMI)-related common genetic polymorphisms modulate the associations between serum lipid levels, BMI and disability progression in multiple sclerosis (MS). METHODS: The association between disability progression (annualised Expanded Disability Status Scale (EDSS) change over 5 years, ΔEDSS) and lipid-related or BMI-related genetic polymorphisms was evaluated in a longitudinal cohort (n=184), diagnosed with MS. We constructed a cumulative genetic risk score (CGRS) of associated polymorphisms (p<0.05) and examined the interactions between the CGRS and lipid levels (measured at baseline) in predicting ΔEDSS. All analyses were conducted using linear regression. RESULTS: Five lipid polymorphisms (rs2013208, rs9488822, rs17173637, rs10401969 and rs2277862) and one BMI polymorphism (rs2033529) were nominally associated with ΔEDSS. The constructed lipid CGRS showed a significant, dose-dependent association with ΔEDSS (ptrend=1.4×10-6), such that participants having ≥6 risk alleles progressed 0.38 EDSS points per year faster compared with those having ≤3. This CGRS model explained 16% of the variance in ΔEDSS. We also found significant interactions between the CGRS and lipid levels in modulating ΔEDSS, including high-density lipoprotein (HDL; pinteraction=0.005) and total cholesterol:high-density lipoprotein ratio (TC:HDL; pinteraction=0.030). The combined model (combination of CGRS and the lipid parameter) explained 26% of the disability variance for HDL and 27% for TC:HDL. INTERPRETATION: In this prospective cohort study, both lipid levels and lipid-related polymorphisms individually and jointly were associated with significantly increased disability progression in MS. These results indicate that these polymorphisms and tagged genes might be potential points of intervention to moderate disability progression.

Common genetic variation within miR-146a predicts disease onset and relapse in multiple sclerosis.

Despite extensive studies focusing on the changes in expression of microRNAs (miRNAs) in multiple sclerosis (MS) compared to healthy controls, few studies have evaluated the association of genetic variants of miRNAs with MS clinical course. We investigated whether a functional polymorphism in the MS associated miR-146a gene predicted clinical course (hazard of conversion to MS and of relapse, and annualized change in disability), using a longitudinal cohort study of persons with a first demyelinating event followed up to their 5-year review. We found the genotype (GC+CC) of rs2910164 predicted relapse compared with the GG genotype (HR=2.09 (95% CI 1.42, 3.06), p=0.0001), as well as a near-significant (p=0.07) association with MS conversion risk. Moreover, we found a significant additive interaction between rs2910164 and baseline anti-EBNA-1 IgG titers predicting risk of conversion to MS (relative excess risk due to interaction [RERI] 2.39, p=0.00002) and of relapse (RERI 1.20, p=0.006). Supporting these results, similar results were seen for the other EBV-correlated variables: anti-EBNA-2 IgG titers and past history of infectious mononucleosis. There was no association of rs2910164 genotype for disability progression. Our findings provide evidence for miR-146a and EBV infection in modulating MS clinical course.

Genetic variation in the gene LRP2 increases relapse risk in multiple sclerosis.

BACKGROUND: Due to the lack of prospective studies with longitudinal data on relapse, past genetic studies have not attempted to identify genetic factors that predict relapse risk (the primary endpoint of many pivotal clinical trials testing the efficacy of multiple sclerosis (MS) disease-modifying drugs) at a genome-wide scale. METHODS: We conducted a genome-wide association analysis (GWAS) to identify genetic variants that predict MS relapse risk, using a three-stage approach. First, GWAS was conducted using the southern Tasmania MS Longitudinal Study with 141 cases followed prospectively for a mean of 2.3 years. Second, GWAS was conducted using the Ausimmune Longitudinal Study with 127 cases having a classic first demyelinating event followed for 5 years from onset. Third, the top hits with p<5.0×10-6 from the first two stages were combined with a longitudinal US paediatric MS cohort with 181 cases followed for 5 years after onset. Predictors of time to relapse were evaluated by a mixed effects Cox model. An inverse variance fixed effects model was then used to undertake a meta-analysis. RESULTS: In the pooled results, using these three unique longitudinal MS cohorts, we discovered one novel locus (LRP2; most significant single nucleotide polymorphism rs12988804) that reached genome-wide significance in predicting relapse risk (HR=2.18, p=3.30×10-8). LRP2 is expressed on the surface of many central nervous system cells including neurons and oligodendrocytes and is a critical receptor in axonal guidance. CONCLUSIONS: The finding of a genetic locus that has extensive effects on neuronal development and repair is of interest as a potential modulator of MS disease course.

Role of genetic susceptibility variants in predicting clinical course in multiple sclerosis: a cohort study.

BACKGROUND: The genetic drivers of multiple sclerosis (MS) clinical course are essentially unknown with limited data arising from severity and clinical phenotype analyses in genome-wide association studies. METHODS: Prospective cohort study of 127 first demyelinating events with genotype data, where 116 MS risk-associated single nucleotide polymorphisms (SNPs) were assessed as predictors of conversion to MS, relapse and annualised disability progression (Expanded Disability Status Scale, EDSS) up to 5-year review (ΔEDSS). Survival analysis was used to test for predictors of MS and relapse, and linear regression for disability progression. The top 7 SNPs predicting MS/relapse and disability progression were evaluated as a cumulative genetic risk score (CGRS). RESULTS: We identified 2 non-human leucocyte antigen (HLA; rs12599600 and rs1021156) and 1 HLA (rs9266773) SNP predicting both MS and relapse risk. Additionally, 3 non-HLA SNPs predicted only conversion to MS; 1 HLA and 2 non-HLA SNPs predicted only relapse; and 7 non-HLA SNPs predicted ΔEDSS. The CGRS significantly predicted MS and relapse in a significant, dose-dependent manner: those having ≥5 risk genotypes had a 6-fold greater risk of converting to MS and relapse compared with those with ≤2. The CGRS for ΔEDSS was also significant: those carrying ≥6 risk genotypes progressed at 0.48 EDSS points per year faster compared with those with ≤2, and the CGRS model explained 32% of the variance in disability in this study cohort. CONCLUSIONS: These data strongly suggest that MS genetic risk variants significantly influence MS clinical course and that this effect is polygenic.

Genetic loci for Epstein-Barr virus nuclear antigen-1 are associated with risk of multiple sclerosis.

BACKGROUND: Infection with the Epstein-Barr virus (EBV) is associated with an increased risk of multiple sclerosis (MS). OBJECTIVE: We sought genetic loci influencing EBV nuclear antigen-1 (EBNA-1) IgG titers and hypothesized that they may play a role in MS risk. METHODS: We performed a genome-wide association study (GWAS) of anti-EBNA-1 IgG titers in 3599 individuals from an unselected twin family cohort, followed by a meta-analysis with data from an independent EBNA-1 GWAS. We then examined the shared polygenic risk between the EBNA-1 GWAS (effective sample size (Neff) = 5555) and a large MS GWAS (Neff = 15,231). RESULTS: We identified one locus of strong association within the human leukocyte antigen (HLA) region, of which the most significantly associated genotyped single nucleotide polymorphism (SNP) was rs2516049 (p = 4.11 × 10-9). A meta-analysis including data from another EBNA-1 GWAS in a cohort of Mexican-American families confirmed that rs2516049 remained the most significantly associated SNP (p = 3.32 × 10-20). By examining the shared polygenic risk, we show that the genetic risk for elevated anti-EBNA-1 titers is positively correlated with the development of MS, and that elevated EBNA-1 titers are not an epiphenomena secondary to MS. In the joint meta-analysis of EBNA-1 titers and MS, loci at 1p22.1, 3p24.1, 3q13.33, and 10p15.1 reached genome-wide significance (p < 5 × 10-8). CONCLUSIONS: Our results suggest that apart from the confirmed HLA region, the association of anti-EBNA-1 IgG titer with MS risk is also mediated through non-HLA genes, and that studies aimed at identifying genetic loci influencing EBNA immune response provides a novel opportunity to identify new and characterize existing genetic risk factors for MS.

Genetic basis of neurocognitive decline and reduced white-matter integrity in normal human brain aging.

Identification of genes associated with brain aging should markedly improve our understanding of the biological processes that govern normal age-related decline. However, challenges to identifying genes that facilitate successful brain aging are considerable, including a lack of established phenotypes and difficulties in modeling the effects of aging per se, rather than genes that influence the underlying trait. In a large cohort of randomly selected pedigrees (n = 1,129 subjects), we documented profound aging effects from young adulthood to old age (18-83 y) on neurocognitive ability and diffusion-based white-matter measures. Despite significant phenotypic correlation between white-matter integrity and tests of processing speed, working memory, declarative memory, and intelligence, no evidence for pleiotropy between these classes of phenotypes was observed. Applying an advanced quantitative gene-by-environment interaction analysis where age is treated as an environmental factor, we demonstrate a heritable basis for neurocognitive deterioration as a function of age. Furthermore, by decomposing gene-by-aging (G × A) interactions, we infer that different genes influence some neurocognitive traits as a function of age, whereas other neurocognitive traits are influenced by the same genes, but to differential levels, from young adulthood to old age. In contrast, increasing white-matter incoherence with age appears to be nongenetic. These results clearly demonstrate that traits sensitive to the genetic influences on brain aging can be identified, a critical first step in delineating the biological mechanisms of successful aging.

Genome-wide genetic and transcriptomic investigation of variation in antibody response to dietary antigens.

Increased immunoglobulin G (IgG) response to dietary antigens can be associated with gastrointestinal dysfunction and autoimmunity. The underlying processes contributing to these adverse reactions remain largely unknown, and it is likely that genetic factors play a role. Here, we estimate heritability and attempt to localize genetic factors influencing IgG antibody levels against food-derived antigens using an integrative genomics approach. IgG antibody levels were determined by ELISA in >1,300 Mexican Americans for the following food antigens: wheat gliadin; bovine casein; and two forms of bovine serum albumin (BSA-a and BSA-b). Pedigree-based variance components methods were used to estimate additive genetic heritability (h(2) ), perform genome-wide association analyses, and identify transcriptional signatures (based on 19,858 transcripts from peripheral blood lymphocytes). Heritability estimates were significant for all traits (0.15-0.53), and shared environment (based on shared residency among study participants) was significant for casein (0.09) and BSA-a (0.33). Genome-wide significant evidence of association was obtained only for antibody to gliadin (P = 8.57 × 10(-8) ), mapping to the human leukocyte antigen II region, with HLA-DRA and BTNL2 as the best candidate genes. Lack of association of known celiac disease risk alleles HLA-DQ2.5 and -DQ8 with antigliadin antibodies in the studied population suggests a separate genetic etiology. Significant transcriptional signatures were found for all IgG levels except BSA-b. These results demonstrate that individual genetic differences contribute to food antigen antibody measures in this population. Further investigations may elucidate the underlying immunological processes involved.

Genetic Determinants of Epigenetic Patterns: Providing Insight into Disease.

The field of epigenetics and our understanding of the mechanisms that regulate the establishment, maintenance and heritability of epigenetic patterns continue to grow at a remarkable rate. This information is providing increased understanding of the role of epigenetic changes in disease, insight into the underlying causes of these epigenetic changes and revealing new avenues for therapeutic intervention. Epigenetic modifiers are increasingly being pursued as therapeutic targets in a range of diseases, with a number of agents targeting epigenetic modifications already proving effective in diseases such as cancer. Although it is well established that DNA mutations and aberrant expression of epigenetic modifiers play a key role in disease, attention is now turning to the interplay between genetic and epigenetic factors in complex disease etiology. The role of genetic variability in determining epigenetic profiles, which can then be modified by environmental and stochastic factors, is becoming more apparent. Understanding the interplay between genetic and epigenetic factors is likely to aid in identifying individuals most likely to benefit from epigenetic therapies. This goal is coming closer to realization because of continual advances in laboratory and statistical tools enabling improvements in the integration of genomic, epigenomic and phenotypic data.

Stimulated PBMC-produced IFN-γ and TNF-α are associated with altered relapse risk in multiple sclerosis: results from a prospective cohort study.

BACKGROUND: Altered reactivity of peripheral blood mononuclear cells (PBMC) and their production of cytokines may affect multiple sclerosis (MS) clinical course. We assessed the relationship of stimulated PBMC-produced IFN-γ, TNF-α, IL-4 and IL-10 in modulating relapse risk using a prospective cohort with established relapsing-remitting MS. METHODS: Cytokine production from PBMCs taken in summer and winter was measured by ELISA. Predictors of cytokines assessed by multilevel mixed-effects linear regression. Predictors of relapse assessed by survival analysis. RESULTS: Increasing IFN-γ was associated with increasing relapse risk, while increasing TNF-α reduced relapse risk after adjusting for IFN-γ. IL-10 and IL4 were not consistently associated with relapse risk. IFN-γ's effects on relapse were greatly attenuated by immunomodulatory therapies, by summer season and by higher serum vitamin D, whereas TNF-α's inverse association with relapse was only present in these circumstances. The TNF-α inverse association with relapse was only present among persons carrying the wild-type of the functional SNP rs1800693 in TNFRSF1A that has been previously associated with MS risk. CONCLUSIONS: We found strong effects of IFN-γ and TNF-α on relapse risk, these differing by immunomodulatory therapy, season, and serum vitamin D, as well as by genotype. These results indicate altered reactivity of immune cells modulate MS disease.

Novel modulating effects of PKC family genes on the relationship between serum vitamin D and relapse in multiple sclerosis.

BACKGROUND: The interplay between genes and environmental factors on multiple sclerosis (MS) clinical course has been little studied. METHODS: We conducted a prospective cohort study of 141 participants with relapsing-remitting MS (RRMS) and genotype data followed from 2002 to 2005 and examined genes in the vitamin D metabolism and vitamin D receptor (VDR)/retinoid X receptor (RXR) transcription factor formation pathway. Gene-vitamin D interactions and the genetic predictors of relapse were assessed using survival analysis. Genetic predictors of 25-hydroxyvitamin D (25(OH)D) were evaluated by multilevel mixed-effects linear regression. Significance threshold was adjusted by Bonferroni correction for the number of genes evaluated. RESULTS: The relationship between 25(OH)D and hazard of relapse was significantly different for different alleles of two intronic single nucleotide polymorphisms (SNPs) (rs908742 in PRKCZ and rs3783785 in PRKCH) in the protein kinase C (PKC) family genes (p(interaction)=0.001, p(adj)=0.021, respectively). Two other intronic SNPs (rs1993116 in CYP2R1and rs7404928 in PRKCB) were significantly associated with lower levels of 25(OH)D (p(interaction)=0.001, p(adj)=0.021, respectively). A cumulative effect of multiple 'risk' genotypes on 25(OH)D levels and hazard of relapse was observed for the significant SNPs (p(trend)=7.12×10(-6) for 25(OH)D levels, p(trend)=8.86×10(-6) for hazard of relapse). CONCLUSIONS: Our data support the hypothesis that gene-vitamin D interactions may influence MS clinical course and that the PKC family genes may play a role in the pathogenesis of MS relapse through modulating the association between 25(OH)D and relapse.

The potential role of epigenetic modifications in the heritability of multiple sclerosis.

It is now well established that both genetic and environmental factors contribute to and interact in the development of multiple sclerosis (MS). However, the currently described causal genetic variants do not explain the majority of the heritability of MS, resulting in 'missing heritability'. Epigenetic mechanisms, which principally include DNA methylation, histone modifications and microRNA-mediated post-transcriptional gene silencing, may contribute a significant component of this missing heritability. As the development of MS is a dynamic process potentially starting with inflammation, then demyelination, remyelination and neurodegeneration, we have reviewed the dynamic epigenetic changes in these aspects of MS pathogenesis and describe how environmental risk factors may interact with epigenetic changes to manifest in disease.

Association between multiple sclerosis risk-associated SNPs and relapse and disability--a prospective cohort study.

BACKGROUND: The modulating effects of the multiple sclerosis (MS) risk-associated single-nucleotide polymorphisms (SNPs) on MS clinical course are not well established. OBJECTIVES: The objective of this paper is to investigate whether known MS risk-associated SNPs were associated with clinical course, and whether these SNPs modified the 25(OH)D-relapse association. METHODS: Using a prospective cohort of 141 participants with relapsing-remitting MS and genotype data followed between 2002 and 2005, genotype-vitamin D interactions and the genetic predictors of relapse were assessed using survival analysis, and genetic predictors of 25(OH)D and disability progression were evaluated by multilevel mixed-effects linear regression. RESULTS: While no SNP reached statistical significance after multiple testing, five SNPs were associated with relapse, with significant cumulative genotype risk effects and two demonstrated significant allele dose-response. Two SNPs altered the 25(OH)D-relapse association with significant allele dose-response. Five SNPs modified levels of 25(OH)D, with significant cumulative genotype 'risk' effect, and three demonstrated significant allele dose-response. We found no consistent evidence for an association between any SNPs and disability. CONCLUSIONS: Our study provides evidence for an association between known MS risk-associated SNPs and relapse. Our findings indicate gene-environment interactions may be an important mechanism on MS clinical course, and provide support for the role of vitamin D in MS relapse.

Measuring the impact of rare diseases in Tasmania, Australia.

BACKGROUND: An ongoing challenge with rare diseases is limited data and, consequently, limited knowledge about the collective prevalence and impact of these conditions on individuals, families, and the health system, particularly in rural and regional areas. Using existing datasets, this project aimed to examine the epidemiology of and hospital activity for Tasmanians with rare diseases. METHODS: Rare diseases were defined as non-infectious diseases with a prevalence of less than 1 in 2000. An initial resource set of 1028 ICD-10-AM diagnostic codes was used to identify a cohort of Tasmanians with rare diseases in Tasmanian Health datasets (1 January 2007 until 31 December 2020). Validating the resource set using a small group with known rare diseases revealed limitations in ascertainment, and so an expanded set of 1940 ICD-10-AM diagnostic codes was developed by cross-referencing ICD-10-AM codes with Orphanet data. Cohort hospital activity and admission costs were compared to statewide data for the final year of the study, 01 January 2020 to 31 December 2020. RESULTS: Using the resource set of 1028 ICD-10-AM diagnostic codes, the period prevalence of rare diseases in Tasmania across all age groups was estimated at 3.5%, with a point prevalence of 1.5% in December 2020. In 2020, 3384 individuals within the Tasmanian rare disease cohort, representing 0.6% of the Tasmanian population, accessed the public hospital system and accounted for 5.6% of all admissions. The mean length of stay for rare disease-related hospital admissions was 5.0 days, compared to 3.3 days for non-rare disease-related admissions. The mean cost per admission for the rare disease cohort was AUD$11,310, compared to AUD$6475 for all admissions statewide. In 2020, using the expanded resource set, the total cost of public hospital admissions in Tasmania was estimated to be AUD$979 million, with rare disease-related hospital admissions accounting for 9.1% of this cost, increasing to 19.0% when the costs for all admissions for the rare disease patients were included. CONCLUSIONS: Patients with rare diseases had more admissions, longer length of stay, and a higher average cost per admission. Patients with rare diseases have a disproportionate impact on statewide hospital activity and costs in Tasmania.

The association between disability progression, relapses, and treatment in early relapse onset MS: an observational, multi-centre, longitudinal cohort study.

The indirect contribution of multiple sclerosis (MS) relapses to disability worsening outcomes, and vice-versa, remains unclear. Disease modifying therapies (DMTs) are potential modulators of this association. Understanding how these endo-phenotypes interact may provide insights into disease pathogenesis and treatment practice in relapse-onset MS (ROMS). Utilising a unique, prospectively collected clinical data from a longitudinal cohort of 279 first demyelinating event cases followed for up to 15 years post-onset, we examined indirect associations between relapses and treatment and the risk of disability worsening, and vice-versa. Indirect association parameters were estimated using joint models for longitudinal and survival data. Early relapses within 2.5 years of MS onset predicted early disability worsening outcomes (HR = 3.45, C.I 2.29-3.61) per relapse, but did not contribute to long-term disability worsening thereinafter (HR = 0.21, C.I 0.15-0.28). Conversely, disability worsening outcomes significantly contributed to relapse risk each year (HR = 2.96, C.I 2.91-3.02), and persisted over time (HR = 3.34, C.I 2.90-3.86), regardless of DMT treatments. The duration of DMTs significantly reduced the hazards of relapses (1st-line DMTs: HR = 0.68, C.I 0.58-0.79; 3rd-line DMTs: HR = 0.37, C.I 0.32-0.44) and disability worsening events (1st-line DMTs: HR = 0.74, C.I 0.69-0.79; 3rd-line DMTs: HR = 0.90, C.I 0.85-0.95), respectively. Results from time-dynamic survival probabilities further revealed individuals having higher risk of future relapses and disability worsening outcomes, respectively. The study provided evidence that in ROMS, relapses accrued within 2.5 years of MS onset are strong indicators of disability worsening outcomes, but late relapses accrued 2.5 years post onset are not overt risk factors for further disability worsening. In contrast, disability worsening outcomes are strong positive predictors of current and subsequent relapse risk. Long-term DMT use and older age strongly influence the individual outcomes and their associations.