Linkage analysis and whole exome sequencing identify a novel candidate gene in a Dutch multiple sclerosis family.

BACKGROUND: Multiple sclerosis (MS) is a complex disease resulting from the joint effect of many genes. It has been speculated that rare variants might explain part of the missing heritability of MS. OBJECTIVE: To identify rare coding genetic variants by analyzing a large MS pedigree with 11 affected individuals in several generations. METHODS: Genome-wide linkage screen and whole exome sequencing (WES) were performed to identify novel coding variants in the shared region(s) and in the known 110 MS risk loci. The candidate variants were then assessed in 591 MS patients and 3169 controls. RESULTS: Suggestive evidence for linkage was obtained to 7q11.22-q11.23. In WES data, a rare missense variant p.R183C in FKBP6 was identified that segregated with the disease in this family. The minor allele frequency was higher in an independent cohort of MS patients than in healthy controls (1.27% vs 0.95%), but not significant (odds ratio (OR) = 1.33 (95% confidence interval (CI): 0.8-2.4), p = 0.31). CONCLUSION: The rare missense variant in FKBP6 was identified in a large Dutch MS family segregating with the disease. This association to MS was not found in an independent MS cohort. Overall, genome-wide studies in larger cohorts are needed to adequately investigate the role of rare variants in MS risk.

High neurofilament levels are associated with clinically definite multiple sclerosis in children and adults with clinically isolated syndrome.

BACKGROUND: A promising biomarker for axonal damage early in the disease course of multiple sclerosis (MS) is neurofilament light chain (NfL). It is unknown whether NfL has the same predictive value for MS diagnosis in children as in adults. OBJECTIVE: To explore the predictive value of NfL levels in cerebrospinal fluid (CSF) for MS diagnosis in paediatric and adult clinically isolated syndrome (CIS) patients. METHODS: A total of 88 adult and 65 paediatric patients with a first attack of demyelination were included and followed (mean follow up-time in adults: 62.8 months (standard deviation (SD) ±38.7 months) and 43.8 months (SD ±27.1 months) in children). Thirty control patients were also included. Lumbar puncture was done within 6 months after onset of symptoms. NfL was determined in CSF using enzyme-linked immunosorbent assay (ELISA). COX regression analyses were used to calculate hazard ratios (HR) for clinically definite multiple sclerosis (CDMS) diagnosis. RESULTS: After adjustments for age, oligoclonal bands (OCB), and asymptomatic T2 lesions on baseline magnetic resonance imaging (MRI), increased NfL levels in both paediatric and adult CIS patients were associated with a shorter time to CDMS diagnosis (children HR = 3.7; p = 0.007, adults HR = 2.1; p = 0.032). For CIS patients with a future CDMS diagnosis, children showed higher NfL levels than adults (geometric mean 4888 vs 2156 pg/mL; p = 0.007). CONCLUSION: CSF NfL levels are associated with CDMS diagnosis in children and adults with CIS. This makes NfL a promising predictive marker for disease course with potential value in clinical practice.

Fatigue after a first attack of suspected multiple sclerosis.

BACKGROUND: Fatigue is reported by more than 75% of multiple sclerosis (MS) patients. In an earlier study, we showed that fatigue is not only a common symptom in patients at time of clinically isolated syndrome (CIS; fatigued 46%) but also predicts subsequent diagnosis of clinically definite multiple sclerosis (CDMS). The course of fatigue after CIS is unknown. OBJECTIVE: We aimed to explore the long-term course of fatigue after CIS. METHODS: In this study, 235 CIS patients, aged 18-50 years, were prospectively followed. Patients filled in the Krupp's Fatigue Severity Scale (FSS) and the Hospital Anxiety and Depression Scale (HADS) at baseline and annually. After reaching CDMS diagnosis, Expanded Disability Status Scale (EDSS) was obtained annually. Mixed-effects models were used to analyse longitudinal FSS measurements. RESULTS: Fatigue at baseline was an independent predictor for CDMS diagnosis (hazard ratio (HR): 2.6, 95% confidence interval (CI): 1.6-4.4). The evolution of FSS was the same in CIS patients who remained monophasic and patients who were diagnosed with CDMS during follow-up. However, FSS increased by 0.86 units after reaching CDMS diagnosis ( p = 0.01). After this increase, the FSS course remained unaltered ( p = 0.44). CONCLUSION: Fatigue, which is often present at time of CIS, probably persists over time and increases after a second attack.

Genome-wide significant association with seven novel multiple sclerosis risk loci.

OBJECTIVE: A recent large-scale study in multiple sclerosis (MS) using the ImmunoChip platform reported on 11 loci that showed suggestive genetic association with MS. Additional data in sufficiently sized and independent data sets are needed to assess whether these loci represent genuine MS risk factors. METHODS: The lead SNPs of all 11 loci were genotyped in 10 796 MS cases and 10 793 controls from Germany, Spain, France, the Netherlands, Austria and Russia, that were independent from the previously reported cohorts. Association analyses were performed using logistic regression based on an additive model. Summary effect size estimates were calculated using fixed-effect meta-analysis. RESULTS: Seven of the 11 tested SNPs showed significant association with MS susceptibility in the 21 589 individuals analysed here. Meta-analysis across our and previously published MS case-control data (total sample size n=101 683) revealed novel genome-wide significant association with MS susceptibility (p<5×10(-8)) for all seven variants. This included SNPs in or near LOC100506457 (rs1534422, p=4.03×10(-12)), CD28 (rs6435203, p=1.35×10(-9)), LPP (rs4686953, p=3.35×10(-8)), ETS1 (rs3809006, p=7.74×10(-9)), DLEU1 (rs806349, p=8.14×10(-12)), LPIN3 (rs6072343, p=7.16×10(-12)) and IFNGR2 (rs9808753, p=4.40×10(-10)). Cis expression quantitative locus effects were observed in silico for rs6435203 on CD28 and for rs9808753 on several immunologically relevant genes in the IFNGR2 locus. CONCLUSIONS: This study adds seven loci to the list of genuine MS genetic risk factors and further extends the list of established loci shared across autoimmune diseases.

EBNA-1 titer gradient in families with multiple sclerosis indicates a genetic contribution.

OBJECTIVE: In multiplex MS families, we determined the humoral immune response to Epstein-Barr virus nuclear antigen 1 (EBNA-1)-specific immunoglobulin γ (IgG) titers in patients with MS, their healthy siblings, and biologically unrelated healthy spouses and investigated the role of specific genetic loci on the antiviral IgG titers. METHODS: IgG levels against EBNA-1 and varicella zoster virus (VZV) as control were measured. HLA-DRB1*1501 and HLA-A*02 tagging single-nucleotide polymorphisms (SNPs) were genotyped. We assessed the associations between these SNPs and antiviral IgG titers. RESULTS: OR for abundant EBNA-1 IgG was the highest in patients with MS and intermediate in their siblings compared with spouses. We confirmed that HLA-DRB1*1501 is associated with abundant EBNA-1 IgG. After stratification for HLA-DRB1*1501, the EBNA-1 IgG gradient was still significant in patients with MS and young siblings compared with spouses. HLA-A*02 was not explanatory for EBNA-1 IgG titer gradient. No associations for VZV IgG were found. CONCLUSIONS: In families with MS, the EBNA-1 IgG gradient being the highest in patients with MS, intermediate in their siblings, and lowest in biologically unrelated spouses indicates a genetic contribution to EBNA-1 IgG levels that is only partially explained by HLA-DRB1*1501 carriership.

Smoking at time of CIS increases the risk of clinically definite multiple sclerosis.

BACKGROUND: Cigarette smoking is a modifiable risk factor that influences the disease course of patients with multiple sclerosis (MS). However, in patients with a clinically isolated syndrome (CIS), there are conflicting results about the association between smoking and the risk of a subsequent MS diagnosis. The aim of this study was to determine the risk of clinically definite MS (CDMS) in smoking and non-smoking patients at time of a first demyelinating event. METHODS: Two hundred and fifty patients, aged 18-50 years, were included in our prospective CIS cohort. At time of the first neurological symptoms, patients completed a questionnaire about smoking habits. Cox regression analyses were performed to calculate univariate and multivariate hazard ratios for CDMS diagnosis in smoking and non-smoking CIS patients. RESULTS: One hundred and fourteen (46%) CIS patients were diagnosed with CDMS during a mean follow-up of 58 months. In total, 79 (32%) patients smoked at time of CIS. Sixty-seven % of the smoking CIS patients were diagnosed with CDMS during follow-up compared to 36% of the non-smoking CIS patients (p < 0.001). Smoking at time of CIS was an independent predictor for CDMS diagnosis (HR 2.3; p = 0.002). Non-smoking CIS patients who had a history of smoking did not have a higher risk for CDMS than those who had never smoked. CONCLUSIONS: Smoking at time of CIS was an independent risk factor for a future CDMS diagnosis. This is an additional argument to quit smoking at time of the first attack of suspected MS.

Application of the 2017 Revised McDonald Criteria for Multiple Sclerosis to Patients With a Typical Clinically Isolated Syndrome.

Importance: In 2017, the International Panel on Diagnosis of Multiple Sclerosis revised the McDonald 2010 criteria for the diagnosis of multiple sclerosis (MS). The new criteria are easier to apply and could lead to more and earlier diagnoses. It is important to validate these criteria globally for their accuracy in clinical practice. Objective: To evaluate the diagnostic accuracy of the 2017 criteria vs the 2010 criteria in prediction of clinically definite MS in patients with a typical clinically isolated syndrome (CIS). Design, Setting and Patients: A total of 251 patients at Erasmus MC, Rotterdam, the Netherlands, in collaboration with several regional hospitals, fulfilled the inclusion criteria. Thirteen patients received another diagnosis early in the diagnostic process and therefore were excluded from the analyses. Nine patients with CIS declined to participate in the study. This left 229 patients who were included between March 2006 and August 2016 in this prospective CIS cohort. Patients underwent a baseline magnetic resonance imaging scan within 3 months after onset of symptoms and, if clinically required, a lumbar puncture was performed. Data were analyzed between December 2017 and January 2018. Main Outcomes and Measures: Sensitivity, specificity, accuracy, and positive and negative predictive value were calculated after 1, 3, and 5 years for the 2017 vs the 2010 criteria. Results: Among the 229 patients with CIS, 167 were women (73%), and the mean (SD) age was 33.5 (8.2) years. One hundred thirteen patients (49%) were diagnosed as having CDMS during a mean (SD) follow-up time of 65.3 (30.9) months. Sensitivity for the 2017 criteria was higher than for the 2010 criteria (68%; 95% CI, 57%-77% vs 36%; 95% CI, 27%-47%; P < .001), but specificity was lower (61%; 95% CI, 50%-71% vs 85%; 95% CI, 76%-92%; P < .001). Using the 2017 criteria, more MS diagnoses could be made at baseline (n = 97 [54%]; 95% CI, 47%-61% vs n = 46 [26%]; 95% CI, 20%-32%; P < .001). In the group with at least 5 years of follow-up, 33% of patients who were diagnosed as having MS using the 2017 criteria did not experience a second attack during follow-up vs 23% when using the 2010 criteria. Conclusions and Relevance: The 2017 revised McDonald criteria are associated with greater sensitivity but less specificity for a second attack than the previous 2010 criteria. The tradeoff is that it leads to a higher number of MS diagnoses in patients with a less active disease course.

Soluble CD27 Levels in Cerebrospinal Fluid as a Prognostic Biomarker in Clinically Isolated Syndrome.

Importance: There is a growing number of therapies that could be administered after the first symptom of central nervous system demyelination. These drugs can delay multiple sclerosis (MS) diagnosis and slow down future disability. However, treatment of patients with benign course may not be needed; therefore, there is a need for biomarkers to predict long-term prognosis in patients with clinically isolated syndrome (CIS). Objective: To investigate whether the T-cell activation marker soluble CD27 (sCD27) measured in cerebrospinal fluid of patients at time of a first attack is associated with a subsequent diagnosis of MS and a higher relapse rate. Design, Setting, and Participants: This prospective study included 77 patients with CIS between March 2002 and May 2015 in a tertiary referral center for multiple sclerosis, in collaboration with several regional hospitals. Patients with CIS underwent a lumbar puncture and magnetic resonance imaging scan within 6 months after first onset of symptoms. Main Outcomes and Measures: Soluble CD27 levels were determined in cerebrospinal fluid using a commercially available enzyme-linked immunosorbent assay. Cox regression analyses was used to calculate univariate and multivariate hazard ratios for MS diagnosis. Association between sCD27 levels and relapse rate was assessed using a negative binomial regression model. Results: Among 77 patients with CIS, 50 were female (79.5%), and mean (SD) age was 32.7 (7.4) years. Mean (SD) age in the control individuals was 33.4 (9.5) years, and 20 were female (66.7%).Patients with CIS had higher cerebrospinal fluid sCD27 levels than control individuals (geometric mean, 31.3 U/mL; 95% CI, 24.0-40.9 vs mean, 4.67 U/mL; 95% CI, 2.9-7.5; P < .001). During a mean (SD) follow-up of 54.8 (35.1) months, 39 of 77 patients (50.6%) were diagnosed as having MS. In a model adjusted for magnetic resonance imaging and cerebrospinal fluid measurements, sCD27 levels were associated with a diagnosis of MS (hazard ratio, 2.4 per 100 U/mL increase in sCD27 levels; 95% CI, 1.27-4.53; P = .007). Additionally, patients with MS with high sCD27 levels (median, >31.4 U/mL) at the time of CIS had a 5.5 times higher annualized relapse rate than patients with low sCD27 levels (annualized relapse rate, 0.06 vs 0.33; P = .02). Conclusions and Relevance: Soluble CD27 in cerebrospinal fluid of patients with CIS was associated with MS diagnosis and a high relapse rate. Therefore, sCD27 is an activation molecule directly related to the immunopathology of the disease and is a potential clinical marker to help in treatment decisions after a first attack of suspected MS.

Burden of genetic risk variants in multiple sclerosis families in the Netherlands.

BACKGROUND: Approximately 20% of multiple sclerosis patients have a family history of multiple sclerosis. Studies of multiple sclerosis aggregation in families are inconclusive. OBJECTIVE: To investigate the genetic burden based on currently discovered genetic variants for multiple sclerosis risk in patients from Dutch multiple sclerosis multiplex families versus sporadic multiple sclerosis cases, and to study its influence on clinical phenotype and disease prediction. METHODS: Our study population consisted of 283 sporadic multiple sclerosis cases, 169 probands from multiplex families and 2028 controls. A weighted genetic risk score based on 102 non-human leukocyte antigen loci and HLA-DRB1*1501 was calculated. RESULTS: The weighted genetic risk score based on all loci was significantly higher in familial than in sporadic cases. The HLA-DRB1*1501 contributed significantly to the difference in genetic burden between the groups. A high weighted genetic risk score was significantly associated with a low age of disease onset in all multiple sclerosis patients, but not in the familial cases separately. The genetic risk score was significantly but modestly better in discriminating familial versus sporadic multiple sclerosis from controls. CONCLUSION: Familial multiple sclerosis patients are more loaded with the common genetic variants than sporadic cases. The difference is mainly driven by HLA-DRB1*1501. The predictive capacity of genetic loci is poor and unlikely to be useful in clinical settings.

Risk genes associated with pediatric-onset MS but not with monophasic acquired CNS demyelination.

OBJECTIVE: To investigate whether 57 genetic risk loci recently identified in a large-scale genome-wide association study in adult patients with multiple sclerosis (MS) are also associated with a risk for pediatric-onset MS and whether they can predict MS diagnosis in children presenting with acquired demyelinating syndromes (ADS). METHODS: We included 188 children with ADS, of whom 53 were diagnosed with MS, 466 patients with adult-onset MS, and 2,046 adult controls in our cohort study. Weighted genetic risk scores (wGRS) were calculated to evaluate genetic effects. RESULTS: Mean wGRS was significantly higher for patients with pediatric-onset MS (7.32 ± 0.53) as compared with patients with monophasic ADS (7.10 ± 0.47, p = 0.01) and controls (7.11 ± 0.53, p < 0.01). We found no difference in mean wGRS of participants with monophasic ADS (7.10 ± 0.47) and controls (7.11 ± 0.53). The ability of the wGRS for the 57 single nucleotide polymorphisms (SNPs) to discriminate between children with MS and those with monophasic ADS was moderate (area under the curve [AUC] = 0.64), but improved with the addition of sex and HLA-DRB1*15 (AUC = 0.70). The combined effect of 57 SNPs exceeded the effect of HLA-DRB1*15 alone in our risk models for pediatric- and adult-onset MS. CONCLUSION: The previously reported 57 SNPs for adult-onset MS also confer increased susceptibility to pediatric-onset MS, but not to monophasic ADS.