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Multiple sclerosis (MS) is a complex and demyelinating disease of the central nervous system. One of the challenges of the post-genome-wide association studies (GWAS) era is to understand the molecular basis of statistical associations to reveal gene networks and potential therapeutic targets. The L3MBTL3 locus has been associated with MS risk by GWAS. To identify the causal variant of the locus, we performed fine mapping in a cohort of 3440 MS patients and 1688 healthy controls. The variant that best explained the association was rs6569648 (P = 4.13E-10, odds ratio = 0.71, 95% confidence interval (CI) = 0.64–0.79), which tagged rs7740107, located in intron 7 of L3MBTL3. The rs7740107 (A/T) variant has been reported to be the best expression and splice quantitative trait locus (eQTL and sQTL) of the region in up to 35 human genotype-tissue expression (GTEx) tissues. By sequencing RNA from blood of 17 MS patients and quantification by digital qPCR, we determined that this eQTL/sQTL originated from the expression of a novel short transcript starting in intron 7 near rs7740107. The short transcript was translated into three proteins starting at different translation initiation codons. These N-terminal truncated proteins lacked the region where L3MBTL3 interacts with the transcriptional regulator Recombination Signal Binding Protein for Immunoglobulin Kappa J Region which, in turn, regulates the Notch signalling pathway. Our data and other functional studies suggest that the genetic mechanism underlying the MS association of rs7740107 affects not only the expression of L3MBTL3 isoforms, but might also involve the Notch signalling pathway.

There are an increasing number of treatments available for multiple sclerosis (MS). The early identification of optimal responders to individual treatments is important to achieve individualized therapy. With this aim, we performed a multicenter retrospective longitudinal study including 186 MS patients treated with natalizumab who were followed for 2 years. We analyzed the following variables at recruitment: sex, current age, age at disease onset, disease duration, EDSS, number of T2 and Gd + lesions, IgG and IgM oligoclonal bands, HLA class II (DR, DRB, DQA, DQB, and DRB1*15:01), IgG and IgM antibody titers against human herpesvirus 6 (HHV-6) and the antibody response to Epstein–Barr virus (EBV) through the measurement of the anti-EBNA-1 and anti-VCA IgG titers, in relation to clinical response (no relapses or disability progression), and to NEDA-3 (no evidence of disease activity in terms of clinical response and no changes in MRI scans either) after 2-years follow-up. Baseline EDSS score, baseline EBNA-1 IgG titers and percentage change of HHV6 IgG titers between baseline and 6 month visits were significantly different in clinical responders and in NEDA-3 status (all of them remained significant in the multivariate analysis). We identified three variables for the early identification of natalizumab optimal responders in a rapid and cost-effective approach.

The detection of IgG aquaporin-4 antibodies in the serum of patients with Neuromyelitis optica (NMO) has dramatically improved the diagnosis of this disease and its distinction from multiple sclerosis. Recently, a group of patients have been described who have an NMO spectrum disorder (NMOsd) and who are seronegative for AQP4 antibodies but positive for IgG aquaporin-1 (AQP1) or myelin oligodendrocyte glycoprotein (MOG) antibodies. The purpose of this study was to determine whether AQP1 and MOG could be considered new biomarkers of this disease, and if point mutations in the gDNA of AQP4, AQP1 and MOG genes could be associated with the etiology of NMOsd. We evaluated the diagnostic capability of ELISA and cell-based assays (CBA), and analyzed their reliability, specificity, and sensitivity in detecting antibodies against these three proteins. The results showed that both assays can recognize these antigen proteins under appropriate conditions, but only anti-AQP4 antibodies, and not AQP1 or MOG, appears to be a clear biomarker for NMOsd. CBA is the best method for detecting these antibodies, and serum levels of AQP4 antibodies do not correlate with the progression of this disease. So far, the sequencing analysis has not revealed a genetic basis for the etiology of NMOsd, but a more extensive analysis is required before definitive conclusions can be drawn.

The importance of studying the cerebrospinal fluid (CSF) in Multiple Sclerosis (MS) is included in the last McDonald criteria (2018). The study of oligoclonal IgG bands (OCGB) assay is strongly recommended in some situations in which MS diagnosis is uncertain. New biomarkers are developed during the last years. Kappa free light chains (FLC) can predict conversion to MS in patients with Clinically Isolated Syndrome (CIS). The aim of this work is to validate the clinical usefulness of the kappa index, and to establish the actual state of knowledge for kappa index as a biomarker of conversion in CIS patients by a meta-analysis. Kappa index seems more relevant than the mere concentration of kappa FLC in CSF. In the validation study, 334 patients were included; in which 100 were CIS patients. Patients were divided in two groups according kappa index cut-off of 10.62: group 1 (kappa index10.62); group 2 (kappa index10.62). In group 1 more patients had positive OCGB, IgG index0.56 and fulfilled magnetic resonance imaging (MRI) criteria. In contrast, in group 2, more patients showed negative OCGB, IgG index0.56 and did not fulfilled MRI criteria. While 67.6% of patients from group 1 converted to MS, only 12.5% of patients from group 2 converted to MS. An HR of 6.02 was obtained in the Kaplan-Meier analysis. In the meta-analysis, 8 studies were finally included. The SROC curve revealed a high diagnostic performance for the kappa index as a MS diagnostic biomarker. Despite heterogeneity found between studies, the global OR revealed a good discriminatory capacity of kappa index. In conclusion, kappa index has a great clinical sensitivity and specificity as a support in MS diagnosis. High kappa index increase the probability of CIS to MS conversion. A correct sample processing in the preanalytical stage is key to obtain right results and to allow establishing comparison between laboratories.

Objective Progressive multifocal leukoencephalopathy (PML) is a serious side effect associated with natalizumab treatment in multiple sclerosis (MS). PML risk increases in individuals seropositive for anti–John Cunningham virus (JC) antibodies, with prolonged duration of natalizumab treatment, and with prior exposure to immunosuppressants. We explored whether the presence of lipid-specific immunoglobulin M oligoclonal bands in cerebrospinal fluid (CSF; IgM bands), a recognized marker of highly inflammatory MS, may identify individuals better able to counteract the potential immunosuppressive effect of natalizumab and hence be associated with a reduced risk of developing PML. Methods We studied 24 MS patients who developed PML and another 343 who did not suffer this opportunistic infection during natalizumab treatment. Patients were recruited at 25 university hospitals. IgM bands were studied by isoelectric focusing and immunodetection. CSF lymphocyte counts were explored in 151 MS patients recruited at Ramon y Cajal Hospital in Madrid, Spain. Results IgM bands were independently associated with decreased PML risk (odds ratio [OR] = 45.9, 95% confidence interval [CI] = 5.9–339.3, p

Objective To identify a biomarker distinguishing patients who, despite a primary progressive multiple sclerosis (PPMS) clinical course, may nonetheless benefit from immune therapy. Methods The presence or absence of both immunoglobulin (Ig) G and IgM oligoclonal bands (OCB) was blindly examined in paired cerebrospinal fluid (CSF) and serum samples from a large PPMS patient cohort, and related to clinical and imaging evidence of focal inflammatory disease activity. Results Using both cross-sectional samples and serial sampling in a subgroup of patients followed prospectively as part of the placebo-controlled OLYMPUS study of rituximab in PPMS, we found that the presence of CSF-restricted IgM OCB (but not of IgG OCB) is associated with an active inflammatory disease phenotype in PPMS patients. This finding was confirmed in an independent, multicenter validation cohort. Interpretation The presence of CSF IgM OCB may be a biomarker for a subset of PPMS patients with more active inflammatory disease, who may benefit from immune-directed treatments. Ann Neurol 2014;76:231–240

An early and accurate diagnosis of multiple sclerosis (MS) is very important, since it allows early treatment initiation, which reduces the activity of the disease. Oligoclonal IgG band (OCGB) detection is a good ancillary tool for MS diagnosis. However, it was argued that its usefulness was limited by the high interlaboratory variability. In the last years, different techniques for OCGB detection have appeared. We performed a blinded aleatorized multicenter study in 19 Spanish hospitals to assess the accuracy and reproducibility of OCGB detection in this new scenario. We studied cerebrospinal fluid (CSF) and serum samples from 114 neurological patients. Every hospital contributed to the study with triplicated pairs of CSF and serum samples of six patients and analyzed 18 different samples. Global analysis rendered a sensitivity of 92.1%, a specificity of 95.1% and a Kappa value of 0.81. This shows that current techniques for OCGB detection have good accuracy and a high interlaboratory reproducibility and thus, represent a good tool for MS diagnosis. When we analyzed separately the different techniques used for OCGB detection, the highest concordance was observed in western blot with alkaline phosphatase detection (kappa=0.91). This indicates that high sensitivity techniques improve the reproducibility of this assay.

Background Multiple sclerosis (MS) initiates with a first attack or clinically isolated syndrome (CIS). The importance of an early treatment in MS leads to the search, as soon as possible, for novel biomarkers which can predict conversion from CIS to MS. Objective The purpose of this study was to assess the predictive value of the kappa index ([Formula: see text] index), using kappa free light light chains ([Formula: see text]FLCs) in cerebrospinal fluid (CSF), for the conversion of CIS patients to MS, and compare its accuracy with other parameters used in clinical practice. Methods FLC levels were analysed in CSF from 176 patients: 70 as control group, 77 CIS, and 29 relapsing–remitting MS. FLC levels were quantified by nephelometry. Results [Formula: see text] Index sensitivity and specificity (93.1%; 95.7%) was higher than those from the immunoglobulin G (IgG) index (75.9%; 94.3%), and lower than those from oligoclonal IgG bands (OCGBs) (96.5%; 98.6%). The optimal cut-off for [Formula: see text] index was 10.62. Most of the CIS patients with [Formula: see text] index >10.62 presented OCGBs, IgG index >0.56 and fulfilled magnetic resonance imaging (MRI) criteria. Conclusion CIS patients above [Formula: see text] index cut-off of 10.62 present 7.34-fold risk of conversion to MS than CIS below this value. The [Formula: see text] index correlated with positive OCGBs, IgG index above 0.56 and MRI criteria.

Several variants in strong linkage disequilibrium (LD) at the SP140 locus have been associated with multiple sclerosis (MS), Crohn's disease (CD) and chronic lymphocytic leukemia (CLL). To determine the causal polymorphism, we have integrated high-density data sets of expression quantitative trait loci (eQTL), using GEUVADIS RNA sequences and 1000 Genomes genotypes, with MS-risk variants of the high-density Immunochip array performed by the International Multiple Sclerosis Genetic Consortium (IMSGC). The variants most associated with MS were also correlated with a decreased expression of the full-length RNA isoform of SP140 and an increase of an isoform lacking exon 7. By exon splicing assay, we have demonstrated that the rs28445040 variant was the causal factor for skipping of exon 7. Western blots of peripheral blood mononuclear cells from MS patients showed a significant allele-dependent reduction of the SP140 protein expression. To confirm the association of this functional variant with MS and to compare it with the best-associated variant previously reported by GWAS (rs10201872), a case-control study including 4384 MS patients and 3197 controls was performed. Both variants, in strong LD (r(2) = 0.93), were found similarly associated with MS [P-values, odds ratios: 1.9E-9, OR = 1.35 (1.22-1.49) and 4.9E-10, OR = 1.37 (1.24-1.51), respectively]. In conclusion, our data uncover the causal variant for the SP140 locus and the molecular mechanism associated with MS risk. In addition, this study and others previously reported strongly suggest that this functional variant may be shared with other immune-mediated diseases as CD and CLL.

Background: The presence of oligoclonal IgM bands (OCMB) in cerebrospinal fluid (CSF) is an unfavourable prognostic marker in multiple sclerosis. There is no commercial test to investigate OCMB status. However, a sensitive and specific isoelectrofocusing (IEF) and western blot method was described. We aimed to study the inter-centre reproducibility of this technique, a necessary condition for a reliable test to be incorporated into clinical practice. Methods: The presence of OCMB was analysed by IEF and western blot with prior reduction of pentameric IgM. We assayed the reproducibility of this test in a blinded multicentre study performed in 13 university hospitals. Paired-CSF and serum samples from 52 neurological patients were assayed at every centre. Results: Global analysis rendered a concordance of 89.8% with a kappa value of 0.71. Conclusion: These data indicate that OCMB detection by means of IEF and western blot with IgM reduction shows a good interlaboratory reproducibility and thus can be used in daily clinical setting. 2014 Elsevier B.V. All rights reserved.

© The Author(s), 2015. Background: Recent findings have shown a correlation between the intrathecal IgG index and variants at the immunoglobulin heavy chain (IGHC) locus in patients with multiple sclerosis (MS). Objectives: The objective of this paper is to analyse the association of the locus with MS susceptibility and its relationship with intrathecal immunoglobulin (Ig) parameters. Methods: We genotyped the rs11621145 variant, located at the IGHC locus, in 2726 patients with MS and 2133 healthy controls. Associations of intrathecal IgG and IgM indexes with rs11621145 were analysed by linear regression analysis in 538 MS patients. Results: We found that rs11621145 showed statistically significant evidence for association with susceptibility to MS (odds ratio = 0.69, p = 1.053E-09), though validation of this result in additional cohorts would be desirable. We confirmed the association between the IgG index and the rs11621145 (p = 6.85E- 07, Beta = 0.207). zFurthermore, rs11621145 was inversely correlated with IgM index (p = 7.24E-04, Beta = -0.277), and therefore marks a decreased likelihood of presenting IgM oligoclonal bands (odds ratio = 0.38, p = 2.35E-06). Conclusions: Our results suggest that the polymorphism of the IGHC locus could be altering the swiching of the Ig isotype in B cells and it may be interfering with T-dependent and T-independent antibody responses., Fondo de Investigación Sanitaria (FIS)-Fondos Europeos de Desarrollo Regional (FEDER) [grant numbers RETICS-REEM- RD12/0032/0015-RD12/0032/0005-RD12/0032/0006-RD12/0032/0009, P12/00555, PI10/01616, PI13/01527, PI13/ 01466, CP10/00526, PI12-00239]; Junta de Andalucía- Fondos Europeos de Desarrollo Regional (FEDER) [grant numbers P07-CVI-02551, P09-CTS-5218].

Vanishing white matter (VWM) is a childhood leukoencephalopathy with central hypomyelination, white matter rarefaction, and cystic degeneration. Adult onset, variable phenotype, and high frequency characterize Arg113His mutation caused by G338A polymorphism associated with VWM. A patient with trauma-associated onset, and clinical features compatible with multiple sclerosis (MS), was homozygous for G338A mutation of eukaryotic translation initiation factor (eIF2B5). The authors checked a cohort of 101 MS patients, including 19 with head/neck trauma-associated onset, and failed to find the mutation, described above, in MS chromosomes. Our report does not exclude the presence in MS chromosomes of other mutations in the eIF2B gene family. Multiple Sclerosis 2007; 13: 424-427. http://msj.sagepub.com

Objective To explore cell subsets and molecules that changed specifically in patients with multiple sclerosis (MS) who had an optimal response to natalizumab. Natalizumab is a monoclonal antibody that inhibits the migration of activated immune cells to the central nervous system. It shows high efficacy in modifying the natural history of MS and induces freedom of disease activity in about 40% of treated patients with MS. Design Prospective study of intrathecal immunoglobulin synthesis and cerebrospinal fluid lymphocyte subsets in patients with MS before and 1 year after beginning treatment with natalizumab. We monitored clinical and magnetic resonance imaging activity during a median time of 2 years. Setting Two tertiary hospitals from the Spanish National Health Service. Patients A total of 23 patients with MS. Main Outcome Measures The differences between patients free of disease activity and patients with active disease during treatment. Results Of the 23 patients, 10 (43.5%) remained free of disease activity during follow-up. The remaining 13 patients (56.5%) had relapses or new lesions despite natalizumab therapy. We did not find differences in demographic variables or clinical data between both groups prior to natalizumab therapy. All patients showed a decrease in cerebrospinal fluid CD4 + cells regardless of their response to treatment. Conversely, only patients free of disease activity showed a decrease in local IgM and, to a lesser extent, in IgG synthesis. They also showed lower percentages of B cells, particularly of CD5 + and plasmablast subsets that virtually disappeared after treatment with natalizumab. Conclusion These data indicate that inhibition of intrathecal antibody synthesis is associated with a complete therapeutic response to natalizumab in patients with aggressive MS.