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BACKGROUND: Multiple sclerosis (MS) and allergies are both considered to be related to imbalanced Th1 and Th2 immune responses. Previous studies evaluating the relationship between MS and allergies provide conflicting results. OBJECTIVE: To assess allergies and asthma as risk factors for MS and as predictors of MS relapses in a pediatric cohort. METHODS: The environment and genetic risk factors for pediatric MS study is a national case-control project with 16 participating US sites. An environmental questionnaire is used that includes history of allergies in the first five years of life. Case-control data are entered in the pediatric MS Network database and cases at 12 of the 16 sites enter relapse data prospectively. Annualized relapse rate was calculated for patients with follow-up and adjusted for age at disease onset, gender, race, ethnicity, and use of disease-modifying therapy (DMT). RESULTS: We included 271 cases (mean age at disease onset of 15.7years and 62% female) and 418 controls. Relapse data were available for 193 cases. There was no difference in prevalence of allergies or asthma between cases and controls. Patients with food allergies had fewer relapses compared to patients without food allergies (0.14 vs 0.48, p=0.01). CONCLUSIONS: While allergies and asthma are not associated with pediatric MS, cases with food allergies have fewer relapses compared to those without food allergies.

Background: Pediatric multiple sclerosis (MS) is rare: only 1.5-5% of MS cases are diagnosed before 18 years of age, and data on disease-modifying therapies (DMTs) for pediatric MS are limited. The CONNECTED study assessed the long-term safety and efficacy of treatment with delayed-release dimethyl fumarate (DMF), an oral MS DMT, in pediatric patients with MS. Methods: CONNECTED is the 96-week extension to FOCUS, a 24-week phase 2 study of patients aged 13-17 years; participants received DMF 240 mg twice daily. Endpoints included (primary) incidence of adverse events (AEs), serious AEs, and DMF discontinuations due to an AE, and (secondary) T2 hyperintense lesion incidence by magnetic resonance imaging and annualized relapse rate (ARR). Results: Twenty participants [median (range) age, 17 (14-18) years; 65% female] who completed FOCUS enrolled into CONNECTED; 17 (85%) completed CONNECTED. Eighteen participants (90%) experienced AEs: the most frequent was flushing (25%). None experienced infections or fever related to low lymphocyte counts. Three participants experienced four serious AEs; none led to DMF discontinuation. Twelve of 17 participants (71%) had no new/newly enlarged T2 lesions from weeks 16-24, two (12%) had one, and one each (6%) had two, three, or five or more lesions [median (range), 0 (0-6)]. Over the full 120-week treatment period, ARR was 0.2, an 84.5% relative reduction ( n = 20; 95% confidence interval: 66.8-92.8; p < 0.0001) vs. the year before DMF initiation. Conclusions: The long-term safety and efficacy observed in CONNECTED was consistent with adults, suggesting pediatric and adolescent patients with MS might benefit from DMF treatment., Competing Interests: RA reports receiving personal compensation for serving on speaker/advisory boards for Bayer, Biogen, Merck, Novartis, Roche, and Sanofi, and receiving research support from Biogen, Merck, Novartis, and Roche for the establishment of regional multiple sclerosis registries and the conduct of clinical trials. PH reports receiving speaker/consulting fees from Bayer, Merck, and Novartis. AB reports receiving speaker/consulting fees from AveXis, Biogen, Genzyme, and Merck. MV reports receiving speaker/consulting fees from Biogen, Genzyme, Merck, Novartis, Roche, and Teva. JP is a contractor for Biogen. XP and VB are employees of and hold stock/stock options in Biogen. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Alroughani, Huppke, Mazurkiewicz-Beldzinska, Blaschek, Valis, Aaen, Pultz, Peng and Beynon.)

Incomplete relapse recovery contributes to disability accrual and earlier onset of secondary progressive multiple sclerosis. We sought to investigate the effect of age on relapse recovery. We identified patients with multiple sclerosis from two longitudinal prospective studies, with an Expanded Disability Status Scale (EDSS) score within 30 days after onset of an attack, and follow-up EDSS 6 months after attack. Adult patients with multiple sclerosis (n = 632) were identified from the Comprehensive Longitudinal Investigations in Multiple Sclerosis at Brigham study (CLIMB), and paediatric patients (n = 132) from the US Network of Paediatric Multiple Sclerosis Centers (NPMSC) registry. Change in EDSS was defined as the difference in EDSS between attack and follow-up. Change in EDSS at follow-up compared to baseline was significantly lower in children compared to adults (P = 0.001), as were several functional system scores. Stratification by decade at onset for change in EDSS versus age found for every 10 years of age, EDSS recovery is reduced by 0.15 points (P < 0.0001). A larger proportion of children versus adults demonstrated improvement in EDSS following an attack (P = 0.006). For every 10 years of age, odds of EDSS not improving increase by 1.33 times (P < 0.0001). Younger age is associated with improved recovery from relapses. Age-related mechanisms may provide novel therapeutic targets for disability accrual in multiple sclerosis., (© The Author(s) (2020). Published by Oxford University Press on behalf of the Guarantors of Brain. All rights reserved. For permissions, please email: journals.permissions@oup.com.)

Objective: Onset of multiple sclerosis (MS) occurs in childhood for approximately 5% of cases (pediatric MS, or ped-MS). Epigenetic influences are strongly implicated in MS pathogenesis in adults, including the contribution from microRNAs (miRNAs), small noncoding RNAs that affect gene expression by binding target gene mRNAs. Few studies have specifically examined miRNAs in ped-MS, but individuals developing MS at an early age may carry a relatively high burden of genetic risk factors, and miRNA dysregulation may therefore play a larger role in the development of ped-MS than in adult-onset MS. This study aimed to look for evidence of miRNA involvement in ped-MS pathogenesis., Methods: GWAS results from 486 ped-MS cases and 1362 controls from the U.S. Pediatric MS Network and Kaiser Permanente Northern California membership were investigated for miRNA-specific signals. First, enrichment of miRNA-target gene network signals was evaluated using MIGWAS software. Second, SNPs in miRNA genes and in target gene binding sites (miR-SNPs) were tested for association with ped-MS, and pathway analysis was performed on associated target genes., Results: MIGWAS analysis showed that miRNA-target gene signals were enriched in GWAS ( P  = 0.038) and identified 39 candidate biomarker miRNA-target gene pairs, including immune and neuronal signaling genes. The miR-SNP analysis implicated dysregulation of miRNA binding to target genes in five pathways, mainly involved in immune signaling., Interpretation: Evidence from GWAS suggests that miRNAs play a role in ped-MS pathogenesis by affecting immune signaling and other pathways. Candidate biomarker miRNA-target gene pairs should be further studied for diagnostic, prognostic, and/or therapeutic utility., Competing Interests: E. Waubant is site PI for a Novartis and Roche trial. She has volunteered on an advisory board for a Novartis trial. She is a nonremunerated advisor for clinical trial design to Novartis, Biogen‐IDEC, Sanofi, Genentech, Serono, and Celgene. She has funding from the NMSS, PCORI, and the Race to Erase MS. She is the section editor for Annals of Clinical and Translational Neurology, and co‐Chief editor for MS And Related Disorders. A. Waldman reports grants from NIH (NINDS) NS071463 and from NMSS during the conduct of the study, as well as funds for investigator‐initiated study from Ionis Pharmaceuticals and Biogen Idec and grants from United Leukodystrophy Foundation outside the submitted work. She is a consultant for Optum and has received royalties from UpToDate. B. Greenberg has received grant funding from Chugai, Medimmune, Medday, National Institutes of Health (NIH), NMSS, Guthy Jackson Charitable Foundation, and Transverse Myelitis Association. He has received consulting fees from Novartis, EMD Serono, Celgene, and Alexion. L. Benson reports BG12 clinical trial support from Biogen, grants from Boston Children's Hospital Office of Faculty Development, travel funds from National MS Society, and personal fees from National Vaccine Compensation Program outside the submitted work. T.C. Casper reports grants from National MS Society. J. Graves reports speaking honoraria from Novartis outside the submitted work. B. Weinstock‐Guttman reports grants and personal fees from Biogen, EMD Serono, Novartis, and Genentech, and personal fees from Mallinckrodt outside the submitted work.

Multiple sclerosis (MS) is an autoimmune disease with high prevalence among populations of northern European ancestry. Past studies have shown that exposure to ultraviolet radiation could explain the difference in MS prevalence across the globe. In this study, we investigate whether the difference in MS prevalence could be explained by European genetic risk factors. We characterized the ancestry of MS-associated alleles using RFMix, a conditional random field parameterized by random forests, to estimate their local ancestry in the largest assembled admixed population to date, with 3,692 African Americans, 4,915 Asian Americans, and 3,777 Hispanics. The majority of MS-associated human leukocyte antigen (HLA) alleles, including the prominent HLA-DRB1*15:01 risk allele, exhibited cosmopolitan ancestry. Ancestry-specific MS-associated HLA alleles were also identified. Analysis of the HLA-DRB1*15:01 risk allele in African Americans revealed that alleles on the European haplotype conferred three times the disease risk compared to those on the African haplotype. Furthermore, we found evidence that the European and African HLA-DRB1*15:01 alleles exhibit single nucleotide polymorphism (SNP) differences in regions encoding the HLA-DRB1 antigen-binding heterodimer. Additional evidence for increased risk of MS conferred by the European haplotype were found for HLA-B*07:02 and HLA-A*03:01 in African Americans. Most of the 200 non-HLA MS SNPs previously established in European populations were not significantly associated with MS in admixed populations, nor were they ancestrally more European in cases compared to controls. Lastly, a genome-wide search of association between European ancestry and MS revealed a region of interest close to the ZNF596 gene on chromosome 8 in Hispanics; cases had a significantly higher proportion of European ancestry compared to controls. In conclusion, our study established that the genetic ancestry of MS-associated alleles is complex and implicated that difference in MS prevalence could be explained by the ancestry of MS-associated alleles., Competing Interests: The authors have declared that no competing interests exist.

Background: There is limited information about the potential associations of multiple sclerosis (MS) and commonly used household chemicals., Methods: We performed a case-control study of exposures to common household chemicals during childhood in children with MS and healthy pediatric controls. Exposures to household products were collected from a comprehensive questionnaire (http://www.usnpmsc.org/Documents/EnvironmentalAssessment.pdf) completed by parents at the time of enrollment in the study. Cases included children diagnosed with MS or clinically isolated syndrome with at least two silent T2 bright lesions on MRI, recruited within 4 years of disease onset from 16 pediatric MS clinics in the USA. Multivariate analyses using logistic regression were adjusted for possible confounders including age, sex, race, ethnicity, mother's highest level of education, and urban versus rural living., Results: Questionnaire responses to household chemicals were available for 312 eligible cases (median age 15.7 years, 63% girls) and 490 healthy controls (median age 15.0, 57% girls). Exposure to rodenticides (odds ratio [OR] 2.10, 95% confidence interval [CI] 1.35-3.26, P  ≤ 0.001), weed control agents (OR 1.99, 95% CI 1.36-2.92, P  ≤ 0.001) and products for plant/tree disease control (OR 2.72, 95% CI 1.54-4.82, P  ≤ 0.001) anytime during childhood were associated with an increased risk for pediatric-onset MS in adjusted and multiple comparisons analyses., Conclusions: Our findings suggest that exposure to specific household chemicals during early childhood is associated with the risk of developing pediatric-onset MS. Future studies are needed to elucidate a causal relationship and the exact agents involved.

Background: We previously identified air quality as a risk factor of interest for pediatric multiple sclerosis. The purpose of this study is to more closely examine the association between the six criteria air pollutants and pediatric MS as well as identify specific areas of toxic release using data from the Toxic Release Inventory., Methods: Pediatric MS cases ( N = 290) and healthy controls ( N = 442) were included as part of an ongoing case-control study. We used the National Emissions Inventory system to estimate particulate exposure by county of residence for each participant. Proximity to Toxic Release Inventory (TRI) sites was also assessed using ArcGIS mapping tools. Risk-Screening Environmental Indicators (RSEI) classified counties at risk to exposure of environmental toxic releases., Results: Fine particulate matter (PM 2.5 ), carbon monoxide (CO), sulfur dioxide (SO 2 ), and lead air emissions were associated with increased odds for pediatric MS ( P < 0.01) for those residing within 20 miles of an MS center. Most study participants (75%) resided within 5 miles of at least one TRI site; however, the mean total pounds of stack air releases was higher for sites near MS cases (81,000 tons) compared to those near healthy controls (35,000 tons, P = 0.002). Average RSEI scores did not differ significantly between cases and controls., Conclusion: Out of several air pollutants examined, we show that fine particulate matter and three other criteria pollutants (SO 2 , CO, and lead) were statistically associated with higher odds for pediatric MS.

Objective: While prior Epstein-Barr virus (EBV) infection has been consistently associated with subsequent risk of developing multiple sclerosis (MS), the association with other common herpesviruses has been more controversial. Our objectives were to determine whether remote infection with EBV and other common herpesviruses affect the susceptibility to pediatric MS and if there are interactions between genetic and demographic factors and viral infections., Methods: Cases with pediatric-onset MS or clinically isolated syndrome within 4 years of disease onset, and controls were recruited from 16 American pediatric MS centers. Logistic regression models adjusted for potential confounders assessed the association between case status and serological evidence for past infection with EBV, cytomegalovirus (CMV), Herpes Simplex viruses-1 (HSV-1) and -2. We determined the heterogeneity of the effect of viral infection on the risk of having MS according to race, ethnicity and HLA-DRB1:1501 status., Results: A total of 356 pediatric cases and 493 controls were recruited. In multivariable models, EBV-viral capsid antigen (VCA) seropositivity was associated with increased odds of having MS by 7.4 times (95% CI: 4.5-12.0, P < 0.001). Seropositivity for HSV-1 was also associated with increased odds of having MS (OR 1.54, 95% CI: 1.06-2.25, P = 0.025) but this increase was seen only in Whites (OR = 2.18, 95% CI 1.35-3.52, P < 0.001) and those negative for HLA-DRB1*1501 (OR = 1.89, 95% CI 1.17-3.03, P = 0.009). The effect of remote EBV infection on the risk of pediatric MS depended on race and HLA-DRB1*15:01 status., Interpretation: EBV seropositivity is strongly associated with pediatric MS, as is HSV-1 seropositivity in subjects negative for HLA-DRB1*15:01 . Our report of interactions between select viral exposures, and age, race and DRB1 status suggests a complex effect of environmental and genetic risk factors on MS development.

Objective: The aim of this study was to examine the relative contributions of body mass index (BMI) and pubertal measures for risk and age of onset of pediatric MS., Methods: Case-control study of 254 (63% female) MS cases (onset<18 years of age) and 420 (49% female) controls conducted at 14 U.S. Pediatric MS Centers. Sex- and age-stratified BMI percentiles were calculated using CDC growth charts from height and weight measured at enrollment for controls, and within 1 year of onset for MS cases. Sex-stratified associations between MS risk and age at symptom onset with both BMI and pubertal factors were estimated controlling for race and ethnicity., Results: Only 11% of girls and 15% of boys were prepubertal (Tanner stage I) at MS onset. 80% of girls had onset of MS after menarche. BMI percentiles were higher in MS cases versus controls (girls: P < 0.001; boys: P = 0.018). BMI was associated with odds of MS in multivariate models in postpubertal girls (OR = 1.60, 95% confidence interval [CI]: 1.12, 2.27, P = 0.009) and boys (OR = 1.43, 95% CI: 1.08, 1.88, P = 0.011). In girls with MS onset after menarche, higher BMI was associated with younger age at first symptoms ( P = 0.031). Younger menarche was associated with stronger effects of BMI through mediation and interaction analysis. In pubertal/postpubertal boys, 89% of whom were obese/overweight, earlier sexual maturity was associated with earlier onset of MS ( P < 0.001)., Interpretation: Higher BMI in early adolescence is a risk factor for MS in girls and boys. Earlier age at sexual maturity contributes to earlier age at MS onset, particularly in association with obesity.