Genes and environment in multiple sclerosis: Impact of temporal changes in the sex ratio on recurrence risks.

OBJECTIVE: To evaluate the impact of temporal increase of female to male (F:M) sex ratio for persons with multiple sclerosis (MS) on the familial risk (empiric recurrence risks or RRs) for biological relatives of affected individuals. METHODS: Detailed family histories were systematically obtained from people with MS attending the University of British Columbia Hospital MS Clinic. The study cohort was born in 1970 or more recently. Data were collected from 1 September 2015 to 31 January 2019. The study was designed to allow only one proband per family. Age-corrected RRs for biological relatives of probands were calculated based on a modification of the maximum-likelihood approach. RESULTS: Data analyses were possible for 746 unique probands (531 females; 215 males) and 19,585 of their biological relatives. RRs were temporally impacted. CONCLUSION: Both genetic sharing and environmental factors are important in determining RRs. It appears that there is an increase in MS risk due to environmental factors in later life (i.e. not shared family environment). Environmental exposures in genetically predisposed individuals might be driving the MS risk. The increase in F:M ratio of RRs for sisters/brothers of female probands over time is likely due to environmental differences.

Risk factors for peripartum depression in women with multiple sclerosis.

BACKGROUND: Peripartum depression (PPD) is underexplored in multiple sclerosis (MS). OBJECTIVE: To evaluate prevalence of and risk factors for PPD in women with MS. METHODS: Retrospective single-center analysis of women with MS with a live birth. Prevalence of PPD was estimated with logistic regression with generalized estimating equations (GEE). GEE evaluated predictors of PPD (e.g. age, marital status, parity, pre-pregnancy depression/anxiety, antidepressant discontinuation, sleep disturbance, breastfeeding, relapses, gadolinium-enhancing lesions, and disability). Factors significant in univariable analyses were included in multivariable analysis. RESULTS: We identified 143 live births in 111 women (mean age 33.1 ± 4.7 years). PPD was found in 18/143 pregnancies (12.6%, 95% CI = 7.3-17.8). Factors associated with PPD included older age (OR 1.16, 95% CI = 1.03-1.32 for 1-year increase), primiparity (OR 4.02, CI = 1.14-14.23), pre-pregnancy depression (OR 3.70, CI = 1.27-10.01), sleep disturbance (OR 3.23, CI = 1.17-8.91), and breastfeeding difficulty (OR 3.58, CI = 1.27-10.08). Maternal age (OR 1.17, CI = 1.02-1.34), primiparity (OR 8.10, CI = 1.38-47.40), and pre-pregnancy depression (OR 3.89, CI = 1.04-14.60) remained significant in multivariable analyses. Relapses, MRI activity, and disability were not associated with PPD. CONCLUSION: The prevalence of PPD in MS appeared similar to the general population, but was likely underestimated due to lack of screening. PPD can affect MS self-management and offspring development, and prospective studies are needed.

NLRX1 inhibits the early stages of CNS inflammation and prevents the onset of spontaneous autoimmunity.

Nucleotide-binding, leucine-rich repeat containing X1 (NLRX1) is a mitochondria-located innate immune sensor that inhibits major pro-inflammatory pathways such as type I interferon and nuclear factor-κB signaling. We generated a novel, spontaneous, and rapidly progressing mouse model of multiple sclerosis (MS) by crossing myelin-specific T-cell receptor (TCR) transgenic mice with Nlrx1-/- mice. About half of the resulting progeny developed spontaneous experimental autoimmune encephalomyelitis (spEAE), which was associated with severe demyelination and inflammation in the central nervous system (CNS). Using lymphocyte-deficient mice and a series of adoptive transfer experiments, we demonstrate that genetic susceptibility to EAE lies within the innate immune compartment. We show that NLRX1 inhibits the subclinical stages of microglial activation and prevents the generation of neurotoxic astrocytes that induce neuronal and oligodendrocyte death in vitro. Moreover, we discovered several mutations within NLRX1 that run in MS-affected families. In summary, our findings highlight the importance of NLRX1 in controlling the early stages of CNS inflammation and preventing the onset of spontaneous autoimmunity.

Exome sequencing in multiple sclerosis families identifies 12 candidate genes and nominates biological pathways for the genesis of disease.

Multiple sclerosis (MS) is an inflammatory disease of the central nervous system characterized by myelin loss and neuronal dysfunction. Although the majority of patients do not present familial aggregation, Mendelian forms have been described. We performed whole-exome sequencing analysis in 132 patients from 34 multi-incident families, which nominated likely pathogenic variants for MS in 12 genes of the innate immune system that regulate the transcription and activation of inflammatory mediators. Rare missense or nonsense variants were identified in genes of the fibrinolysis and complement pathways (PLAU, MASP1, C2), inflammasome assembly (NLRP12), Wnt signaling (UBR2, CTNNA3, NFATC2, RNF213), nuclear receptor complexes (NCOA3), and cation channels and exchangers (KCNG4, SLC24A6, SLC8B1). These genes suggest a disruption of interconnected immunological and pro-inflammatory pathways as the initial event in the pathophysiology of familial MS, and provide the molecular and biological rationale for the chronic inflammation, demyelination and neurodegeneration observed in MS patients.

Genetic analysis of nucleotide-binding leucine-rich repeat (NLR) receptors in multiple sclerosis.

Genetic and functional analyses of the inflammasome suggest a role for this multiprotein complex in the biological mechanisms leading to the onset and progression of multiple sclerosis (MS). Nucleotide-binding, leucine-rich repeat (NLR) receptors trigger the activation and assembly of specific inflammasomes in response to danger signals. Mining exome sequencing data from 326 MS patients identified 17 rare missense or nonsense variants in NLR family pyrin domain containing 1 (NLRP1), NLRP3, NLRP6, NLRP7 and NLR family CARD domain containing 4 (NLRC4). Genotyping these variants in 2503 MS cases and 1076 healthy controls did not result in statistically significant differences between groups, and segregation analysis within MS families was largely unsupportive of co-segregation of these variants with disease. However, the identification of MS patients harboring rare homozygote variants in NLRP1 (p.Ile601Phe and p.Ser1387Ile), a variant in NLRP3 (p.Leu832Ile) resulting in the substitution of a critical amino acid for the formation of its leucine-rich repeat domain, and several MS patients with NLRC4 variants (p.Arg310Ter and p.Glu600Ter) causing protein truncations suggest that rare protein-altering variants in inflammasome-activating NLR receptors may contribute to MS risk.

Canadian Multiple Sclerosis Pregnancy Study (CANPREG-MS): Rationale and Methodology.

BACKGROUND: Multiple sclerosis (MS) is the most common cause of neurological disability, other than trauma, among young adults of reproductive age. In contrast to the past, today there is very little lag time from clinical onset to diagnosis. Disease-modifying therapies are also now available outside of clinical trials. However, there is very little evidence-based population data to help an individual with MS make informed decisions with respect to reproductive options. OBJECTIVE: The objective of this study is to develop a Canada-wide, prospective population-based registry of women with MS who are either trying to become pregnant and/or have become pregnant. METHODS: The study represents a "real-world" scenario. Women with MS are invited to participate, regardless of clinical course, therapy, disease duration, and/or disability. The methodology to develop such a registry is very complex making it imperative to understand the design and rationale when interpreting results for clinical purposes. RESULTS: This paper is a comprehensive discussion of the study rationale and methodology. CONCLUSIONS: The study is ongoing, with over 100 potential participants. Numerous future publications are envisioned as the study progresses. The present paper is thus designed to be the key referral paper for subsequent publications in which it will not be possible to provide the necessary detailed information on rationale and methodology.

Fondements et méthodologie de l'étude de cohorte prospective canadienne sur la grossesse dans le contexte de la sclérose en plaques. Contexte : Outre les traumatismes, la sclérose en plaques (SP) demeure la cause la plus fréquente d'invalidité neurologique parmi les jeunes adultes en âge de procréer. Contrairement au passé, les délais entre l'apparition des premiers signes cliniques de SP et un diagnostic sont de nos jours passablement courts. Qui plus est, des traitements modificateurs de la maladie (TMM) sont dorénavant disponibles en dehors d'un contexte d'essais cliniques. Cela dit, il existe encore peu de données probantes basées sur des études populationnelles en vue d'aider une personne atteinte de la SP à prendre des décisions éclairées quant à ses options en matière de reproduction. Objectif : L'objectif de cette étude est d'élaborer, à l'échelle canadienne, un registre prospectif de femmes atteintes de SP qui essaient de devenir enceintes et/ou qui le sont devenues. Méthodes : Cette étude repose sur un scénario ancré dans « la vie réelle ¼. Ainsi, des femmes atteintes de SP ont été invitées à y participer quels que soient l'évolution clinique de leur état de santé, leurs traitements, la durée de leur maladie et/ou leur degré d'invalidité. La méthodologie permettant d'élaborer un tel registre demeure très complexe, ce qui rend impérieux la compréhension de sa conception et de ses fondements au moment d'interpréter nos résultats à des fins cliniques. Résultats : Cet article constitue une discussion approfondie de la méthodologie et des fondements de cette étude. Conclusions : Toujours en cours, cette étude peut compter sur plus de 100 participants potentiels. De nombreuses publications subséquentes sont également envisagées au fur et à mesure de sa progression. Le présent article est par conséquent destiné à devenir une référence clé pour d'autres articles dans lesquels il ne sera pas possible d'indiquer tous les renseignements détaillés en ce qui regarde la méthodologie et les fondements de cette étude.

Increased mean R2* in the deep gray matter of multiple sclerosis patients: Have we been measuring atrophy?

BACKGROUND: Magnetic resonance relaxometry studies in multiple sclerosis (MS) have suggested that iron accumulates within deep gray matter (DGM) structures early in the disease course. However, the commonly utilized mean R2* and magnetic susceptibility measures reflect regional iron concentration but not a structure's total iron content. Thus, tissue atrophy could impact mean R2* and magnetic susceptibility estimates. PURPOSE: To demonstrate that both average iron concentration and total iron content need to be reported in order to distinguish between atrophy-related and definite magnetic susceptibility changes. STUDY TYPE: Observational. POPULATION: The study was performed on 30 healthy controls (HCs) and 39 people with definite MS. FIELD STRENGTH/SEQUENCE: 3T Philips Achieva using an 8-channel SENSE head coil. R2* data were acquired using a multiecho gradient echo sequence and diffusion tensor imaging data were acquired using an echo-planar sequence. ASSESSMENT: Total iron content in DGM structures was assessed by calculating the sum of all R2* values within a region (denoted as R2mass* ) and compared to the mean R2* as a measure of iron concentration. STATISTICAL TEST: Significant group differences were investigated in a linear regression model. All DGM structures were assessed individually and the significance threshold was adjusted using the Bonferroni-Holm correction for multiple comparisons. RESULTS: There was an increased mean DGM R2* in MS patients compared to HCs (significant in the pallidus, P = 0.0051). In contrast, R2mass* in patients was found to be lower in the thalamus and the caudate (P = 0.0011) compared to HCs, and similar between the two cohorts in the other DGM regions. DATA CONCLUSION: An increase in mean R2* may not necessarily reflect increased iron accumulation. We propose R2mass* as an additional metric to account for the effects of tissue atrophy when assessing tissue content changes, such as iron deposition or loss. LEVEL OF EVIDENCE: 1 Technical Efficacy: Stage 1 J. Magn. Reson. Imaging 2019;50:201-208.

Analysis of NOD-like receptor NLRP1 in multiple sclerosis families.

The implementation of exome sequencing technologies has started to unravel the genetic etiology of familial multiple sclerosis (MS). A homozygote p.G587S mutation in NLRP1 has been suggested as potentially causative for the onset of MS in an affected sibling pair, who later developed malignant melanoma. To validate the proposed role of recessive NLRP1 mutations in the pathological mechanisms of MS, we examined exome sequencing data from 326 MS patients from Canada for the identification of NLRP1 missense and nonsense variants. This analysis did not identify the previously described p.G587S mutation; however, three patients with potential NLRP1 compound heterozygote mutations were observed. Haplotype and segregation analyses indicate that the variants observed in these patients were inherited in cis, and do not segregate with disease within families. Thus, the analysis of MS patients from Canada failed to identify potentially pathogenic mutations in NLRP1, including the previously described p.G587S mutation. Further studies are necessary to confirm a role of NLRP1 in the pathophysiology of MS.

Purinergic receptors P2RX4 and P2RX7 in familial multiple sclerosis.

Genetic variants in the purinergic receptors P2RX4 and P2RX7 have been shown to affect susceptibility to multiple sclerosis (MS). In this study, we set out to evaluate whether rare coding variants of major effect could also be identified in these purinergic receptors. Sequencing analysis of P2RX4 and P2RX7 in 193 MS patients and 100 controls led to the identification of a rare three variant haplotype (P2RX7 rs140915863:C>T [p.T205M], P2RX7 rs201921967:A>G [p.N361S], and P2RX4 rs765866317:G>A [p.G135S]) segregating with disease in a multi-incident family with six family members diagnosed with MS (logarithm of odds = 3.07). Functional analysis of this haplotype in HEK293 cells revealed impaired P2X7 surface expression (P < 0.01), resulting in over 95% inhibition of adenosine triphosphate (ATP)-induced pore function (P < 0.001) and a marked reduction in phagocytic ability (P < 0.05). In addition, transfected cells showed 40% increased peak ATP-induced inward current (P < 0.01), and a greater Ca2+ response to the P2X4 135S variant compared with wild type (P < 0.0001). Our study nominates rare genetic variants in P2RX4 and P2RX7 as major genetic contributors to disease, further supporting a role for these purinergic receptors in MS and the disruption of transmembrane cation channels leading to impairment of phagocytosis as the pathological mechanisms of disease.

Genetic modifiers of multiple sclerosis progression, severity and onset.

The genetic contribution to clinical outcomes for multiple sclerosis (MS) has yet to be defined. We performed exome sequencing analysis in 100 MS patients presenting opposite extremes of clinical phenotype (discovery cohort), and genotyped variants of interest in 2016 MS patients (replication cohort). Linear and logistic regression analyses were used to identify significant associations with disease course, severity and onset. Our analysis of the discovery cohort nominated 38 variants in 21 genes. Replication analysis identified PSMG4 p.W99R and NLRP5 p.M459I to be associated with disease severity (p=0.002 and 0.008). CACNA1H p.R1871Q was found associated with patients presenting relapsing remitting MS at clinical onset (p=0.028) whereas NLRP5 p.M459I and EIF2AK1 p.K558R were associated with primary progressive disease (p=0.031 and 0.023). In addition, PSMG4 p.W99R and NLRP5 p.R761L were found to correlate with an earlier age at MS clinical onset, and MC1R p.R160W with delayed onset of clinical symptoms (p=0.010-0.041).

Common genetic etiology between "multiple sclerosis-like" single-gene disorders and familial multiple sclerosis.

Several single-gene disorders with clinical and radiological characteristics similar to those observed in multiple sclerosis (MS) patients have been described. To evaluate whether this phenotypic overlap can be ascribed to a common genetic etiology, 28 genes known to present pathogenic mutations for 24 of these disorders were sequenced in 270 MS patients. All identified variants were genotyped in 2131 MS cases and 830 healthy controls, and those exclusively observed in patients were assessed for segregation within families. This analysis identified 9 rare variants in 6 genes segregating with disease in 13 families. Four different mutations were identified in CYP27A1, including a reported pathogenic mutation for cerebrotendinous xanthomatosis (p.R405W), which was observed in six patients from a multi-incident family, three diagnosed with MS, two with an undefined neurological disease and one seemingly healthy. A LYST p.V1678A and a PDHA1 p.K387Q mutation were both observed in five MS patients from three separate multi-incident families. In addition, CLCN2 p.V174G, GALC p.D162E and POLG p.R361G were each identified in two MS patients from one family. This study suggests a shared genetic etiology between MS and the characterized single-gene disorders, and highlights cholesterol metabolism and the synthesis of oxysterols as important biological mechanisms for familial MS.

Patient-Reported Benefits of Extracranial Venous Therapy: British Columbia CCSVI Registry.

Objective Chronic cerebrospinal venous insufficiency (CCSVI) has been hypothesized to be a risk factor for multiple sclerosis (MS). Venoplasty has been proposed as a treatment for CCSVI. The aim of our study was to gain a better understanding of the "real-world" safety and longitudinal effectiveness of venoplasty Methods: British Columbia residents who self-reported having had venoplasty and consented to participate in the study were interviewed and followed for up to 24 months post-therapy using standardized structured questionnaires Results: Participants reported procedure-related complications (11.5%) and complications within the first month after the procedure (17.3%). Initially, more than 40% of participants perceived that the venoplasty had had positive effects on their health conditions, such as fatigue, numbness, balance, concentration/memory and mobility. However, this improvement was not maintained over time Conclusions: Follow-up patient-reported outcomes indicated that the initial perception of the positive impact of venoplasty on the health conditions of MS patients was not sustained over time. In addition, venoplasty was not without associated morbidity.

Prevalence of Extracranial Venous Narrowing on Magnetic Resonance Venography Is Similar in People With Multiple Sclerosis, Their Siblings, and Unrelated Healthy Controls: A Blinded, Case-Control Study.

PURPOSE: The study sought to assess and compare the prevalence of narrowing of the major extracranial veins in subjects with multiple sclerosis and controls, and to assess the sensitivity and specificity of magnetic resonance venography (MRV) for describing extracranial venous narrowing as it applies to the chronic cerebrospinal venous insufficiency theory, using catheter venography (CV) as the gold standard. METHODS: The jugular and azygos veins were assessed with time-of-flight MRV in this assessor-blinded, case-control study of subjects with multiple sclerosis, their unaffected siblings, and unrelated controls. The veins were evaluated by diameter and area, and compared with CV. Collateral vessels were also analyzed for maximal diameter, as a potential indicator of compensatory flow. RESULTS: A high prevalence of extracranial venous narrowing was demonstrated in all study groups, collectively up to 84% by diameter criteria and 90% by area, with no significant difference between the groups when assessed independently (P = .34 and .63, respectively). There was high interobserver variability in the reporting of vessel narrowing (kappa = 0.32), and poor vessel per vessel correlation between narrowing on MRV and CV (kappa = 0.064). Collateral neck veins demonstrated no convincing difference in maximum size or correlation with jugular narrowing. CONCLUSION: There is a high prevalence of narrowing of the major extracranial veins on MRV in all 3 study groups, with no significant difference between them. These findings do not support the chronic cerebrospinal venous insufficiency theory. Although MRV has shown a high sensitivity for identifying venous narrowing, time-of-flight imaging demonstrates poor interobserver agreement and poor specificity when compared with the gold standard CV.

Viral exposures and MS outcome in a prospective cohort of children with acquired demyelination.

Epstein-Barr virus (EBV) infection is associated with increased multiple sclerosis (MS) risk. Recently, cytomegalovirus (CMV) infection has been proposed as a protective factor against MS development. We determined EBV, herpes simplex virus, varicella-zoster virus and CMV seroprevalence in 247 prospectively followed children with acquired demyelinating syndromes (ADS). Remote EBV infection was more common in children with MS than those with monophasic ADS while CMV infection was more common in children with monophasic ADS. Children displaying evidence of remote EBV without CMV infection were at highest risk of subsequent MS diagnosis. Viral infection repertoire detected at ADS provides important prognostic information.

Incidence of Multiple Sclerosis and Related Disorders in Asian Populations of British Columbia.

BACKGROUND: Global variation in the incidence of multiple sclerosis (MS) is generally ascribed to differences in genetic and environmental risk factors. Here we investigate temporal trends in the incidence of MS and related disorders in British Columbia, Canada, from 1986 to 2010, focusing particularly on the Asian ethnic subpopulation. METHODS: A longitudinal database was screened to identify newly diagnosed cases of MS and related disorders, including neuromyelitis optica and clinically isolated syndromes. Age-standardized, sex-specific mean annual incidence was calculated for the Asian and non-Asian population of British Columbia for 5-year intervals from 1986 to 2010. Temporal changes and cohort differences in incidence rates and demographic characteristics were evaluated. RESULTS: During this period, the incidence of MS and related disorders in the non-Asian population remained relatively unchanged, from 10.41 (95% confidence interval [CI]: 9.87-10.97) to 9.91 (95% CI: 9.46-10.39) per 100,000 (p=0.167). In contrast, incidence in the Asian population doubled during the same period. This increase was driven by a precipitous rise in the incidence of MS in females from 0.71 (95% CI: 0.01-1.50) to 2.08 (95% CI: 1.43-2.91) per 100,000 (p=0.004), including both Canadian-born and immigrant Asians. The incidence of neuromyelitis optica did not change significantly during this period. CONCLUSIONS: The incidence of MS may be increasing among females in the Asian ethnic population of British Columbia.

Predictors of chronic cerebrospinal venous insufficiency procedure use among older people with multiple sclerosis: a national case-control study.

BACKGROUND: Following the initial reports of Chronic Cerebrospinal Venous Insufficiency (CCSVI) and the purported curative potential of venoplasty, (coined the 'liberation' procedure) Canadians living with multiple sclerosis (MS) began to travel abroad to receive the unregulated procedure, often placing them at odds with their health providers. The purpose of this study was to determine the factors influencing older MS patients' decision to undergo the procedure in order to develop more specific and targeted health information. METHODS: We performed secondary analysis of data collected as part of the 'Canadian Survey of Health Lifestyle and Aging with MS' from people over the age of 55 years with MS symptoms for 20 or more years. The survey consisted of self-reported information on impairments, disability, participation, demographics, personal and environmental factors. In order to compare respondents who underwent the procedure to those who did not and to develop a predictive model, we created a comparison group using a case-control algorithm, controlling for age, gender and education, and matching procedure cases to controls 1:3. We used multivariate stepwise least likelihood regression of 'a priori' variables to determine predictive factors. RESULTS: The prevalence of the 'liberation' procedure in our sample was 12.8% (95/743), substantially lower than reported in previous studies of complementary/alternative treatments in MS. The predictive model contained five factors; living alone (Odds ratio 0.24, 95%CI 0.09-0.63), diagnosis of anxiety (Odds ratio 0.29, 95%CI 0.10 - 0.84), rating of neurologist's helpfulness (Odds ratio 0.56, 95%CI 0.44 -0 .71), Body Mass Index (Odds ratio 0.93, 95%CI, 0.89 - 0.98) and perceived physical impact of MS (Odds ratio 1.02, 95%CI 1.01 - 1.04). CONCLUSIONS: Predictive factors differed from previous studies of complementary/alternative treatment use likely due to both the invasiveness of the procedure and the advanced age of our study cohort. Our findings suggest that health professionals should target information on the risks and benefits of unregulated procedures to those patients who feel dissatisfied with their neurologist and they should include family members in discussions since they may be providing the logistical support to travel abroad and undergo the 'liberation' procedure. Our findings may be applicable to others with chronic disabling conditions who contemplate the user-pay unregulated invasive procedures available to them.

An assessment of genetic counseling services for individuals with multiple sclerosis.

Multiple sclerosis (MS) affects up to 1/500 Canadians. The University of British Columbia MS Clinic (UBC Clinic) is the only MS clinic in Canada (and likely internationally) that routinely offers genetic counseling to patients and their families. A typical session includes the collection of family history and demographic data, discussion of the inheritance of MS, interpretation of family-specific recurrence risks and psychosocial counseling. The aims of this study were to explore patients': 1) expectations of the genetic counseling session; 2) understanding of the etiology of MS (both pre and post-session); and 3) post-session perceptions of genetic counseling. A two-part questionnaire to assess genetic counseling services was distributed before and after sessions to all consenting patients seen during the period October 1, 2008 to February 28, 2009 inclusive. Sixty-two completed questionnaires were analysed. Genetic counseling was found to significantly increase the number of individuals who were able to correctly identify the etiology of MS (p < 0.001). Patient satisfaction with genetic counseling was high, with an average satisfaction score of 32.4/35 (92.6 %). Of those who provided comments (n = 42/60) regarding the usefulness of the genetic counseling session, 95.2 % reported it useful (n = 40/42). Findings suggest that genetic counseling is effective in increasing patients' knowledge of the etiology of MS and is viewed by patients as a useful service. Based on the high level of positive feedback regarding genetic counseling by the study sample, this study suggests that the services provided by genetic counselors may be beneficial for patients with MS seen in other centers.

Genetic variants in IL2RA and IL7R affect multiple sclerosis disease risk and progression.

Multiple sclerosis (MS) is a common demyelinating neurodegenerative disease with a strong genetic component. Previous studies have associated genetic variants in IL2RA and IL7R in the pathophysiology of the disease. In this study, we describe the association between IL2RA (rs2104286) and IL7R (rs6897932) in the Canadian population. Genotyping 1,978 MS patients and 830 controls failed to identify any significant association between these variants and disease risk. However, stratified analysis for family history of disease and disease course identified a trend towards association for IL2RA in patients without a family history (p = 0.05; odds ratio = 0.77) and a significant association between IL7R and patients who developed progressive MS (PrMS) (p = 0.002; odds ratio = 0.73). Although not statistically significant, the effect of IL2RA (rs2104286) in patients without a family history of MS indicates that the genetic components for familial and sporadic disease are perhaps distinct. This data suggests that the onset of sporadic disease is likely determined by a large number of variants of small effect, whereas MS in patients with a family history of disease is caused by a few deleterious variants. In addition, the significant association between PrMS and rs6897932 indicates that IL7R may not be disease-causing but a determinant of disease course. Further characterization of the effect of IL2RA and IL7R genetic variants in defined MS subtypes is warranted to evaluate the effect of these genes on specific clinical outcomes and to further elucidate the mechanisms of disease onset and progression.