Edwards, Alice Rutatangwa

Background and Objectives The genetic basis of adult-onset multiple sclerosis (MS) is well-studied, but less is known about pediatric-onset MS (pedMS), comprising approximately 5% of all MS onsets. Mendelian randomization (MR) studies have demonstrated evidence for a causal association between MS and both 25-hydroxyvitamin D [25(OH)D] serum levels and genetic variation related to vitamin D receptor (VDR) binding. The objective was to identify whether VDR binding variants (VDR-BVs) previously implicated in adult-onset MS were associated with pedMS using genetic instrumental variables (GIVs). Methods Using previously identified VDR-BVs to construct individual GIVs with two-sample MR, we investigated associations with pedMS in 725 cases and 592 controls of European ancestry from the US Network of Pediatric MS Centers. Associations between each VDR-BV and pedMS were estimated using logistic regression adjusting for the first three genome-wide principal components. A significant interaction between a VDR-BV and 25(OH)D GIV provided evidence for a causal association unbiased by pleiotropy. Results One VDR-BV, rs2531804, previously associated with adult-onset MS, was also significantly associated with pedMS after multiple testing correction. Discussion This study is the first to use VDR-BVs from previous MR studies to demonstrate causal differences in VDR binding at a locus contributing to pedMS susceptibility.

Objective To assess real‐world effectiveness of initial treatment with newer compared to injectable disease‐modifying therapies (DMTs) on disease activity in pediatric multiple sclerosis (MS) and clinically isolated syndrome (CIS). Methods This is a cohort study of children with MS/CIS followed at 12 clinics in the US Network of Pediatric MS Centers, who received initial therapy with newer (fingolimod, dimethyl fumarate, teriflunomide, natalizumab, rituximab, ocrelizumab) or injectable (interferon‐β, glatiramer acetate) DMTs. Propensity scores (PSs) were computed, including preidentified confounders. Relapse rate while on initial DMT was modeled with negative binomial regression, adjusted for PS‐quintile. Time to new/enlarging T2‐hyperintense and gadolinium‐enhancing lesions on brain magnetic resonance imaging were modeled with midpoint survival analyses, adjusted for PS‐quintile. Results A total of 741 children began therapy before 18 years, 197 with newer and 544 with injectable DMTs. Those started on newer DMTs were older (15.2 vs injectable 14.4 years, p = 0.001) and less likely to have a monofocal presentation. In PS‐quintile–adjusted analysis, those on newer DMTs had a lower relapse rate than those on injectables (rate ratio = 0.45, 95% confidence interval (CI) = 0.29–0.70, p < 0.001; rate difference = 0.27, 95% CI = 0.14–0.40, p = 0.004). One would need to treat with newer rather than injectable DMTs for 3.7 person‐years to prevent 1 relapse. Those started on newer DMTs had a lower rate of new/enlarging T2 (hazard ratio [HR] = 0.51, 95% CI = 0.36–0.72, p < 0.001) and gadolinium‐enhancing lesions (HR = 0.38, 95% CI = 0.23–0.63, p < 0.001) than those on injectables. Interpretation Initial treatment of pediatric MS/CIS with newer DMTs led to better disease activity control compared to injectables, supporting greater effectiveness of newer therapies. Long‐term safety data for newer DMTs are required. ANN NEUROL 2020 ANN NEUROL 2020;88:42–55

AbstractObjectiveWhile 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.MethodsCases 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.ResultsA 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.InterpretationEBV 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.