Kahn, Ilana

AbstractObjectiveOnset of multiple sclerosis (MS) occurs in childhood for approximately 5% of cases (pediatricMS, or ped‐MS). Epigenetic influences are strongly implicated inMSpathogenesis in adults, including the contribution from microRNAs (miRNAs), small noncodingRNAs that affect gene expression by binding target genemRNAs. Few studies have specifically examined miRNAs in ped‐MS, but individuals developingMSat an early age may carry a relatively high burden of genetic risk factors, and miRNAdysregulation may therefore play a larger role in the development of ped‐MSthan in adult‐onsetMS. This study aimed to look for evidence of miRNAinvolvement in ped‐MSpathogenesis.MethodsGWASresults from 486 ped‐MScases and 1362 controls from the U.S. PediatricMSNetwork and Kaiser Permanente Northern California membership were investigated for miRNA‐specific signals. First, enrichment of miRNA‐target gene network signals was evaluated usingMIGWASsoftware. Second,SNPs in miRNAgenes and in target gene binding sites (miR−SNPs) were tested for association with ped‐MS, and pathway analysis was performed on associated target genes.ResultsMIGWASanalysis showed that miRNA‐target gene signals were enriched inGWAS(P = 0.038) and identified 39 candidate biomarker miRNA‐target gene pairs, including immune and neuronal signaling genes. The miR‐SNPanalysis implicated dysregulation of miRNAbinding to target genes in five pathways, mainly involved in immune signaling.InterpretationEvidence fromGWASsuggests that miRNAs play a role in ped‐MSpathogenesis by affecting immune signaling and other pathways. Candidate biomarker miRNA‐target gene pairs should be further studied for diagnostic, prognostic, and/or therapeutic utility.

AbstractBackgroundThere is limited information about the potential associations of multiple sclerosis (MS) and commonly used household chemicals.MethodsWe 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.ResultsQuestionnaire 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.ConclusionsOur 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.