BCG vaccination and multiple sclerosis risk: A Norwegian cohort study.

INTRODUCTION: Bacillus Calmette-Guérin (BCG) vaccination induces long-lasting effects on the adaptive and innate immune systems and prevents development of experimental autoimmune encephalomyelitis and possibly also inflammatory disease activity in multiple sclerosis (MS). OBJECTIVE: The objective is to examine if BCG given in early adulthood decreases MS risk. METHODS: From 791,369 (52% females) Norwegians participating in a national tuberculosis screening program from 1963 to 1975, we collected information on BCG vaccination and tuberculosis disease status. Later, MS disease was ascertained through both the Norwegian MS Registry and Biobank and the Norwegian Death Registry. We used logistic regression models to assess the relationship between BCG vaccination and MS risk. RESULTS: In those BCG vaccinated, mean age at vaccination was 15.6 (standard deviation (SD) = 5.5) years. A total of 2862 (65% females) MS cases were retrieved. Overall, we found no association between MS risk and BCG vaccination. Compared to non-BCG-vaccinated individuals with no signs of tuberculosis infection, odds ratio (OR) for MS was 1.00 (95% confidence interval (CI) = 0.80-1.25) in the BCG-vaccinated group. In those not BCG vaccinated because of latent tuberculosis infection, the corresponding OR was 0.86 (95% CI = 0.66-1.13). CONCLUSION: We found no evidence of BCG vaccination or latent tuberculosis infection in young adulthood being linked to MS risk.

Predictors of hospitalization due to infection in rituximab-treated MS patients.

BACKGROUND: Rituximab is extensively used off-label to treat multiple sclerosis (MS), and long-term vigilance for adverse events is needed. This study was conducted to determine frequencies and predictors of hematological adverse events, including hypogammaglobulinemia, severe lymphopenia, neutropenia, and infections leading to hospitalization. METHODS: This retrospective cohort study included all patients with MS initiating rituximab treatment at Haukeland University Hospital between January 1st, 2017, and July 1st, 2021. Patients were followed by clinical monitoring and repeated blood sampling every six months. Clinical outcomes and laboratory results were retrieved from the Norwegian MS Registry and Biobank and the patient administrative system at Haukeland University Hospital. RESULTS: Five hundred and fifty-six patients were included, 515 with relapsing-remitting MS (RRMS) and 41 with progressive MS. Overall, 33 patients (5.9%) experienced 56 episodes of infections requiring hospital admission. Sixty patients (10.8%) had confirmed hypogammaglobulinemia, 17 (3.1%) had confirmed severe lymphopenia, and 10 (1.8%) had confirmed severe neutropenia. Predictors of infection requiring hospital admission were progressive MS (adjusted OR (aOR): 4.81; 95%CI: 1.25-18.48), duration of treatment with rituximab (aOR: 1.52; 95%CI: 1.11-2.09) and confirmed severe lymphopenia (aOR: 13.58; 95%CI: 3.41-54.06) and neutropenia (aOR: 13.40; 95%CI: 2.93-61.25). Of the hematological abnormalities, only hypogammaglobulinemia was associated with treatment duration (aOR: 1.35; 95%CI: 1.09-1.69). CONCLUSION: The risk of hospitalization due to infection is associated with time on rituximab treatment, in patients with lympho- or neutropenia, and in patients with primary progressive MS. We observed a time-dependent decline in IgG values, in contrast to neutrophil and lymphocyte count, suggesting a cumulative dose-dependent response. These predictors can assist clinicians in assessing and monitoring MS patients receiving rituximab.

Humoral immunity to SARS-CoV-2 mRNA vaccination in multiple sclerosis: the relevance of time since last rituximab infusion and first experience from sporadic revaccinations.

INTRODUCTION: The effect of disease-modifying therapies (DMT) on vaccine responses is largely unknown. Understanding the development of protective immunity is of paramount importance to fight the COVID-19 pandemic. OBJECTIVE: To characterise humoral immunity after mRNA-COVID-19 vaccination of people with multiple sclerosis (pwMS). METHODS: All pwMS in Norway fully vaccinated against SARS-CoV-2 were invited to a national screening study. Humoral immunity was assessed by measuring anti-SARS-CoV-2 SPIKE RBD IgG response 3-12 weeks after full vaccination, and compared with healthy subjects. RESULTS: 528 pwMS and 627 healthy subjects were included. Reduced humoral immunity (anti-SARS-CoV-2 IgG <70 arbitrary units) was present in 82% and 80% of all pwMS treated with fingolimod and rituximab, respectively, while patients treated with other DMT showed similar rates as healthy subjects and untreated pwMS. We found a significant correlation between time since the last rituximab dose and the development of humoral immunity. Revaccination in two seronegative patients induced a weak antibody response. CONCLUSIONS: Patients treated with fingolimod or rituximab should be informed about the risk of reduced humoral immunity and vaccinations should be timed carefully in rituximab patients. Our results identify the need for studies regarding the durability of vaccine responses, the role of cellular immunity and revaccinations.

Cancer related mortality in multiple sclerosis. A population based cohort study.

BACKGROUND: Cancer is a major cause of death, but how cancer influences mortality risk in Multiple Sclerosis (MS) is unclear. OBJECTIVES: Determine all-cause mortality and mortality following a cancer diagnosis among MS patients compared with matched population controls. METHODS: Norwegian MS patients born 1930 - 1979 (n= 6950) followed-up 1953 - 2016, were matched with 37 922 controls. We compared incident cancer diagnosis from the Cancer Registry of Norway, date of death from the Cause of Death Registry, education from the National Education Database, by multivariate Cox proportional hazard regression. RESULTS: Hazard ratio (HR) and 95% confidence interval (CI) for all-cause mortality among MS patients was 4.97 (4.64 - 5.33), and 2.61 (2.29 - 2.98) for mortality following a cancer diagnosis. Mortality in MS was highest following urinary- (2.53: 1.55 - 4.14), colorectal- (2.14: 1.47 - 3.11), hematological- (1.76: 1.08 - 2.88), ovarian - 2.30 (1.73-3.06) and breast cancer diagnosis (2.61: 1.85 - 3.68), compared to controls. High education was inversely associated with mortality among MS patients. CONCLUSIONS: All-cause mortality was five- fold and mortality following a cancer diagnosis was two- fold increased among MS patients. Mortality following specific cancers raises the possibility of diagnostic neglect.

Mortality and cause of death in multiple sclerosis in western Norway 1950-2021: a registry-based linkage study.

BACKGROUND: Persons with multiple sclerosis (pwMS) have higher risk of mortality compared with the general population. Longitudinal studies are important for understanding the evolution of survival in pwMS. OBJECTIVE: Examine changes in mortality among pwMS during the past seven decades. METHODS: We followed pwMS from Hordaland and Møre and Romsdal in Western Norway, with disease onset from before 1950, identified from population-based epidemiological surveys and the Norwegian MS Registry and Biobank, until 1 January 2021. Data were linked to the Norwegian Cause of Death Registry to obtain underlying cause of death. We examined all-cause, and cause-specific mortality using standardised mortality ratios (SMR) and excess death rates (EDR). We calculated life expectancies and assessed survival stratified by sex, age and disease phenotype at onset. We compared hazard ratios (HRs) for mortality, in pwMS diagnosed before and after the era of disease-modifying treatment (DMT). RESULTS: Of 3624 pwMS, 964 (55.5% women) had died, predominantly of multiple sclerosis (49.0%). Median life expectancy for pwMS was 74.3 years (95% CI 73.3 to 75.3), compared with 83.1 years for the general population (p<0.001). From disease onset, pwMS survived 14.6 years shorter than the general population (p<0.001). Overall, SMR was 2.3 (95% CI 2.13 to 2.42) and EDR was 6.8 (95% CI 6.42 to 7.09) for pwMS. Treatment-eligible pwMS diagnosed in the DMT era had the lowest risk of mortality, HR 0.49 (95% CI 0.34 to 0.70,p<0.001). CONCLUSION: Excess mortality among pwMS declined during the past seven decades, possibly due to improved diagnostics, better symptomatic treatment and access to DMTs.

Abuse and revictimization in adulthood in multiple sclerosis: a cross-sectional study during pregnancy.

BACKGROUND: Knowledge concerning exposure to abuse in adulthood and in pregnancy in people with multiple sclerosis (MS) is sparse. OBJECTIVE: To determine the occurrence of adult abuse and abuse in relation to pregnancy in women with MS and their risk of revictimization (repeated abuse as adults after childhood abuse). METHODS: This cross-sectional study comprised pregnant women from the Norwegian Mother, Father and Child Cohort study. Information on abuse was acquired through self-completed questionnaires. We used logistic regression to estimate adjusted odds ratios (aORs) with 95% confidence intervals (CIs). RESULTS: We identified 106 women with MS at enrollment through linkage with national health registries. The reference group consisted of 77,278 women without MS. Twenty-seven women (26%) with MS reported any adult abuse compared to 15,491 women (20%) without MS, aOR 1.33 (0.85-2.09). Twenty-two (21%) women with MS reported systematic emotional abuse compared to 13% without MS, aOR 1.75 (1.08-2.83). Ten women (10%) with MS reported sexual abuse, compared to 6% without MS, aOR 1.72 (0.89-3.33). More women with MS reported rape as an adult, aOR 2.37 (1.02-5.49). Women with MS had higher risk of revictimization as adults, after childhood abuse, aOR 2.23 (1.22-4.10). The risk of abuse during pregnancy or 6 months preceding pregnancy was similar between the groups. CONCLUSIONS: Women with MS had increased occurrence of systematic emotional abuse, rape, and revictimization as adults, compared to women without MS.

Association of adverse childhood experiences with the development of multiple sclerosis.

OBJECTIVE: To study whether exposure to childhood emotional, sexual or physical abuse is associated with subsequent multiple sclerosis (MS) development. METHODS: A nationwide, prospective cohort study based on participants in the Norwegian Mother, Father and Child cohort study. Enrolment took place 1999-2008, with follow-up until 31 December 2018. Childhood abuse before age 18 years was obtained from self-completed questionnaires. We identified MS diagnoses through data-linkage with national health registries and hospital records. The Cox model was used to estimate HRs for MS with 95% CIs, adjusting for confounders and mediators. RESULTS: In this prospective cohort study, 14 477 women were exposed to childhood abuse and 63 520 were unexposed. 300 women developed MS during the follow-up period. 71 of these (24%) reported a history of childhood abuse, compared with 14 406 of 77 697 (19%) women that did not develop MS. Sexual abuse (HR 1.65, 95% CI 1.13 to 2.39) and emotional abuse (HR 1.40, 95% CI 1.03 to 1.90) in childhood were both associated with an increased risk of developing MS. The HR of MS after exposure to physical abuse was 1.31 (95% CI 0.83 to 2.06). The risk of MS was further increased if exposed to two (HR 1.66, 95% CI 1.04 to 2.67) or all three abuse categories (HR 1.93, 95% CI 1.02 to 3.67). INTERPRETATION: Childhood sexual and emotional abuse were associated with an increased risk of developing MS. The risk was higher when exposed to several abuse categories, indicating a dose-response relationship. Further studies are needed to identify underlying mechanisms.

Incidence of cancer in multiple sclerosis before and after the treatment era- a registry- based cohort study.

BACKGROUND: Whether disease-modifying therapies (DMTs) influence cancer in multiple sclerosis (MS) is uncertain. OBJECTIVES: Assess incidence of cancer diagnosis among Norwegian MS patients compared to the general population in 1953 to 1995 and 1996 to 2017-reflecting era before and after introduction of DMTs. METHODS: We performed a nationwide cohort study comprising 6949 MS patients and 37,922 controls, matched on age, sex and county. The cohort was linked to Norwegian Cancer Registry, Cause of Death Registry and National Educational database. We used Poisson regression to calculate incidence rate ratio (IRR) of cancer. RESULTS: During 1953-1995 MS patients had similar cancer frequency compared to controls (IRR: 1.11 (95% Confidence Intervals (CI): 0.90-1.37)), although MS patients had increased frequency of cancer in endocrine glands (IRR: 2.51 (1.27-4.93). During 1996-2017 we identified significant increased frequency of cancer among MS patients compared to controls (IRR: 1.38 (95% CI: 1.28-1.52): in brain (IRR: 1.97 (1.41-2.78)), meninges (IRR: 2.44 (1.54-3.77)), respiratory organs (IRR: 1.96 (1.49-2.63)). The excess cancer diagnosis was most frequent among MS patients ≥ 60 years of age (HR 1.30 (1.15-1.47)). CONCLUSION: Incidence of cancer among MS patients compared to controls was higher in 1996 to 2017, corresponding in time to the introduction of DMT for MS. This was observed more frequently among MS patients older than 60 years of age.

Safety and efficacy of rituximab as first- and second line treatment in multiple sclerosis - A cohort study.

BACKGROUND: Rituximab is increasingly used as off-label therapy in multiple sclerosis (MS). More data are needed on safety and efficacy of rituximab, particularly in cohorts of de novo patients and patients in early therapy escalation. OBJECTIVE: To investigate the safety and efficacy of off-label treatment with rituximab in an MS-cohort of predominantly de novo patients or as therapy escalation. METHODS: We retrieved safety and efficacy data from the Norwegian MS-registry and biobank for all MS-patients treated with rituximab at Haukeland University Hospital, Bergen, Norway, during a four year period. RESULTS: In the 365 MS-patients (320 relapsing-remitting MS (RRMS), 23 secondary progressive MS (SPMS), and 22 primary progressive MS (PPMS)), the overall annualized relapse rate (ARR) was 0.03 and annualized drug discontinuation rate (ADDR) was 0.05. NEDA-3 was achived in 79% of patients with available data (n=351). Sixty-one patients experienced infusion-related adverse events of which two were serious (CTCAE grade 3-4). Eighteen patients experienced serious non-infusion related adverse events, of which 16 were infections. Infections (n = 34; 9.3%, CTCAE grade 2-5), hypogammaglobulinemia (n = 19, 5.2%) and neutropenia (n = 16; 4.4%) were the most common non-infusion-related adverse events. CONCLUSION: Rituximab was a safe and highly efficient disease modifying therapy in this cohort of MS-patients; however, infections and neutropenia need to be monitored.

Perinatal Depression and Anxiety in Women With Multiple Sclerosis: A Population-Based Cohort Study.

OBJECTIVE: To assess the occurrence of perinatal depression and anxiety in women before and after diagnosis of multiple sclerosis (MS). METHODS: A total of 114,629 pregnant women were included in the Norwegian Mother, Father and Child Cohort study (1999-2008). We assessed depression and anxiety by questionnaires during and after pregnancy. Women with MS were identified from national health registries and hospital records and grouped into (1) MS diagnosed before pregnancy (n = 140) or MS diagnosed after pregnancy with (2) symptom onset before pregnancy (n = 98) or (3) symptom onset after pregnancy (n = 308). Thirty-five women were diagnosed with MS in the postpartum period. The reference group (n = 111,627) consisted of women without MS. RESULTS: Women with MS diagnosed before pregnancy had an adjusted odds ratio of 2.0 (95% confidence interval, 1.2-3.1) for depression in the third trimester. Risk factors were adverse socioeconomic factors and history of psychiatric disease and physical/sexual abuse. The risk of anxiety was not increased. Women diagnosed with MS in the postpartum period had especially high risk of postpartum depression. Women with MS symptom onset within 5 years after pregnancy had increased risk of both depression and anxiety during pregnancy, whereas women with more than 5 years until symptom onset did not. CONCLUSION: Women diagnosed with MS have increased risk of perinatal depression. Women with MS symptom onset within 5 years after pregnancy have increased risk of both depression and anxiety during pregnancy.

High incidence and prevalence of MS in Møre and Romsdal County, Norway, 1950-2018.

OBJECTIVE: To determine prevalence and longitudinal trends in incidence of MS in Møre and Romsdal County, Western Norway, from 1950 to 2018. METHODS: Retrospective longitudinal population-based observational study. All patients diagnosed, or living, with MS in Møre and Romsdal were identified as incident or prevalent cases from local, regional, and national sources. We compiled the data in the Norwegian Multiple Sclerosis Registry and Biobank and used the aggregated data set to calculate incidence and prevalence rates using population measures obtained from Statistics Norway. RESULTS: On January 1, 2018, the estimated prevalence was 335.8 (95% CI, 314.1-358.5) per 100,000 inhabitants, with a female:male ratio of 2.3. From 1950 through 2017, we observed a considerable (p < 0.001) increase in average annual incidence rates from 2.1 (95% CI, 1.3-3.3) to 14.4 (95% CI, 11.9-17.3) per 100,000. From 2005 through 2017, the incidence among women increased from 17.1 (95% CI, 14.0-20.7) to 23.2 (95% CI, 18.7-28.5) per 100,000, whereas the incidence among men declined from 10.3 (95% CI, 7.9-13.2) to 5.9 (95% CI, 3.4-8.8) per 100,000. CONCLUSION: Møre and Romsdal County in Western Norway has the highest prevalence of MS reported in Norway. The incidence has steadily increased since 1950, and during the latest 15 years, we observed opposing trends in sex-specific incidence rates.

Risk of cancer among multiple sclerosis patients, siblings, and population controls: A prospective cohort study.

BACKGROUND: Risk of cancer in multiple sclerosis (MS) patients compared to their siblings is unknown. OBJECTIVE: The objective was to prospectively investigate the risk of cancer among MS patients compared to siblings without MS and to population controls. METHODS: We retrieved data on MS patients born between 1930 and 1979 from the Norwegian Multiple Sclerosis Registry and population studies and on cancer diagnosis from the Cancer Registry of Norway. We used adjusted Cox proportional hazard regression to estimate cancer risk among 6883 MS patients, 8918 siblings without MS, and 37,919 population controls. RESULTS: During 65 years of follow-up, cancer risk among MS patients was higher than that among population controls (hazard ratio (HR) = 1.14, 95% confidence interval (CI): 1.05-1.23) in respiratory organs (HR = 1.66, 95% CI: 1.26-2.19), urinary organs (HR = 1.51, 95% CI: 1.12-2.04), and the central nervous system (HR = 1.52, 95% CI: 1.11-2. 09). Siblings had higher risk of hematological cancers compared with MS patients (HR = 1.82, 95% CI: 1.21-2.73) and population controls (HR = 1.72, 95% CI: 1.36-2.18). CONCLUSION: MS patients were associated with increased risk of cancer compared to population controls. Siblings had increased risk of hematological cancer. This indicates that MS and hematological cancer could share a common etiology.

Antiepileptic and psychiatric medication in a nationwide cohort of patients with glioma WHO grade II-IV.

INTRODUCTION: Glioma is the most common intracranial primary brain tumor. Patients with glioma often suffer from epilepsy, anxiety and depression. Aims of this study were to identify risk factors for drug-treated anxiety and depression, and to determine the use of psychiatric medication in a national glioma cohort. METHODS: Data from the Cancer Registry of Norway on all persons diagnosed with glioma WHO grade II-IV 2004-2010 were linked with data from the Norwegian Prescription Database. Cox regression analysis was used to assess risk factors for drug-treated anxiety and depression. Standardized incidence ratios were calculated for psychiatric medication dispensed to glioma patients and compared to the general population. RESULTS: The glioma cohort consisted of 1056 males and 772 females. Of the 1828 patients, 565 had glioma grade II-III, and 1263 had grade IV. The patients with glioma grade II-III who were treated with levetiracetam had an increased risk for drug-treated anxiety compared to patients without levetiracetam; hazard ratio 2.8 (95% confidence interval 1.7-4.9). Female gender increased the risk for drug-treated anxiety compared to males in patients with glioma grade IV; hazard ratio 1.5 (95% confidence interval 1.2-2.0). Antidepressants were less frequently dispensed to patients with glioma grade II-III and epilepsy than to the general population. CONCLUSIONS: Patients with glioma grade II-III on levetiracetam had an increased risk for drug-treated anxiety. The subgroup of patients with glioma grade II-III and epilepsy received less antidepressants than the general population.

Increased levels of cell-free mitochondrial DNA in the cerebrospinal fluid of patients with multiple sclerosis.

Mitochondrial DNA (mtDNA) can act as damage-associated molecular pattern molecule (DAMP) and initiate an inflammatory response. We hypothesized that the concentration of mtDNA might reflect inflammatory activity in multiple sclerosis and investigated therefore levels of cell-free mitochondrial DNA in cerebrospinal fluid of patients with relapsing-remitting multiple sclerosis. Significantly higher levels of mtDNA were found in patients compared to controls and there was an inverse correlation between disease duration and mtDNA concentration. Our study suggests that mitochondria can be involved early in multiple sclerosis, but whether this is as an initiator of the inflammatory response or part of its maintenance is unclear. Further, our study suggests that changes in mtDNA may provide a novel marker for early disease activity.

The influence of coping styles on long-term employment in multiple sclerosis: A prospective study.

BACKGROUND: The aim was to investigate predictive values of coping styles, clinical and demographic factors on time to unemployment in patients diagnosed with multiple sclerosis (MS) during 1998-2002 in Norway. METHOD: All patients ( N = 108) diagnosed with MS 1998-2002 in Hordaland and Rogaland counties, Western Norway, were invited to participate in the long-term follow-up study in 2002. Baseline recordings included disability scoring (Expanded Disability Status Scale (EDSS)), fatigue (Fatigue Severity Scale (FSS)), depression (Beck Depression Inventory (BDI)), and questionnaire assessing coping (the Dispositional Coping Styles Scale (COPE)). Logistic regression analysis was used to identify factors associated with unemployed at baseline, and Cox regression analysis to identify factors at baseline associated with time to unemployment during follow-up. RESULTS: In all, 41 (44%) were employed at baseline. After 13 years follow-up in 2015, mean disease duration of 22 years, 16 (17%) were still employed. Median time from baseline to unemployment was 6 years (±5). Older age at diagnosis, female gender, and depression were associated with patients being unemployed at baseline. Female gender, long disease duration, and denial as avoidant coping strategy at baseline predicted shorter time to unemployment. CONCLUSION: Avoidant coping style, female gender, and longer disease duration were associated with shorter time to unemployment. These factors should be considered when advising patients on MS and future employment.

Allelic imbalance of multiple sclerosis susceptibility genes IKZF3 and IQGAP1 in human peripheral blood.

BACKGROUND: Multiple sclerosis is a chronic inflammatory, demyelinating disease of the central nervous system. Recent genome-wide studies have revealed more than 110 single nucleotide polymorphisms as associated with susceptibility to multiple sclerosis, but their functional contribution to disease development is mostly unknown. RESULTS: Consistent allelic imbalance was observed for rs907091 in IKZF3 and rs11609 in IQGAP1, which are in strong linkage disequilibrium with the multiple sclerosis associated single nucleotide polymorphisms rs12946510 and rs8042861, respectively. Using multiple sclerosis patients and healthy controls heterozygous for rs907091 and rs11609, we showed that the multiple sclerosis risk alleles at IKZF3 and IQGAP1 are expressed at higher levels as compared to the protective allele. Furthermore, individuals homozygous for the multiple sclerosis risk allele at IQGAP1 had a significantly higher total expression of IQGAP1 compared to individuals homozygous for the protective allele. CONCLUSIONS: Our data indicate a possible regulatory role for the multiple sclerosis-associated IKZF3 and IQGAP1 variants. We suggest that such cis-acting mechanisms may contribute to the multiple sclerosis association of single nucleotide polymorphisms at IKZF3 and IQGAP1.

Genetic variants are major determinants of CSF antibody levels in multiple sclerosis.

Immunological hallmarks of multiple sclerosis include the production of antibodies in the central nervous system, expressed as presence of oligoclonal bands and/or an increased immunoglobulin G index-the level of immunoglobulin G in the cerebrospinal fluid compared to serum. However, the underlying differences between oligoclonal band-positive and -negative patients with multiple sclerosis and reasons for variability in immunoglobulin G index are not known. To identify genetic factors influencing the variation in the antibody levels in the cerebrospinal fluid in multiple sclerosis, we have performed a genome-wide association screen in patients collected from nine countries for two traits, presence or absence of oligoclonal bands (n = 3026) and immunoglobulin G index levels (n = 938), followed by a replication in 3891 additional patients. We replicate previously suggested association signals for oligoclonal band status in the major histocompatibility complex region for the rs9271640*A-rs6457617*G haplotype, correlated with HLA-DRB1*1501, and rs34083746*G, correlated with HLA-DQA1*0301 (P comparing two haplotypes = 8.88 × 10(-16)). Furthermore, we identify a novel association signal of rs9807334, near the ELAC1/SMAD4 genes, for oligoclonal band status (P = 8.45 × 10(-7)). The previously reported association of the immunoglobulin heavy chain locus with immunoglobulin G index reaches strong evidence for association in this data set (P = 3.79 × 10(-37)). We identify two novel associations in the major histocompatibility complex region with immunoglobulin G index: the rs9271640*A-rs6457617*G haplotype (P = 1.59 × 10(-22)), shared with oligoclonal band status, and an additional independent effect of rs6457617*G (P = 3.68 × 10(-6)). Variants identified in this study account for up to 2-fold differences in the odds of being oligoclonal band positive and 7.75% of the variation in immunoglobulin G index. Both traits are associated with clinical features of disease such as female gender, age at onset and severity. This is the largest study population so far investigated for the genetic influence on antibody levels in the cerebrospinal fluid in multiple sclerosis, including 6950 patients. We confirm that genetic factors underlie these antibody levels and identify both the major histocompatibility complex and immunoglobulin heavy chain region as major determinants.

Month of birth and risk of multiple sclerosis: confounding and adjustments.

A month of birth effect on multiple sclerosis (MS) risk has been reported from different countries. Recent critics have suggested that this finding is caused by confounding and that adequately adjusting for year and place of birth would markedly reduce this effect. All inhabitants in Norway are registered in the Norwegian Population Registry (Statistics Norway), making this an ideal area for performing adjusted analyses. Using the entire Norwegian population born between 1930 and 1979 (n = 2,899,260), we calculated the excess between observed and expected number of births for each month for 6649 Norwegian MS patients, 5711 mothers, 5247 fathers, and 8956 unaffected siblings. The analyses were adjusted for year of birth and place of birth according to the 19 counties in Norway. An unadjusted analysis revealed 13% fewer MS births than expected in February (P = 0.0015; Bonferroni corrected P = 0.018), 10% more in April (P = 0.0083; Bonferroni corrected P = 0.0996) and 15% more in December (P = 0.00058; Bonferroni corrected P = 0.007). Adjustments for both year and place of birth significantly altered our results for February and December, but even after these adjustments there were still 10% more MS births than expected in April (P = 0.00796; Bonferroni corrected P = 0.096). MS patients had a higher incidence of April births than their siblings (Fisher-exact test; P = 0.011), mothers (Fisher-exact test; P = 0.004), and fathers (Fisher-exact test; P = 0.011) without MS. Adjustments for confounding significantly affected our results. However, even after adjustments, there appears to be a persistent higher than expected frequency of April births in the MS population.

Oligoclonal band phenotypes in MS differ in their HLA class II association, while specific KIR ligands at HLA class I show association to MS in general.

Multiple sclerosis (MS) patients have been reported to have different HLA class II allele profiles depending on oligoclonal bands (OCBs) in the cerebrospinal fluid, but HLA class I alleles and killer cell immunoglobulin-like receptor (KIR) ligands have not been studied. We investigated the association of HLA alleles and KIR ligands according to OCB status in MS patients (n=3876). Specific KIR ligands were associated with patients when compared to controls (n=3148), supporting a role for NK cells in MS pathogenesis. HLA class I alleles and KIR ligands did not differ between OCB phenotypes, but HLA class II associations were convincingly replicated.