Cognitive dysfunction 24-31 years after isolated optic neuritis.

OBJECTIVE: Cognitive dysfunction is common in multiple sclerosis (MS), but long-term data on cognition in patients with clinically isolated syndromes are sparse. METHODS: We determined cognitive functions in 22 patients 44-75 years old diagnosed with optic neuritis 24-31 years earlier but had no further clinical bouts and had not progressed clinically to MS. We used a neuropsychological test battery covering nine cognitive domains. Magnetic resonance imaging (MRI) of the brain had been performed earlier and was normal in six patients and showed two or more white matter abnormalities compatible with demyelinating lesions in 16 patients. RESULTS: On neuropsychological testing, one patient was within normal range on all tests, six subjects showed borderline results, and 15 patients (68%) showed significantly impaired performance in at least one cognitive domain. Seven patients showed significant impairment in two or more domains. Executive function, visuo-spatial ability, and information processing speed were the most frequently affected domains. There was no apparent correlation between MRI findings and cognitive function. CONCLUSIONS: We conclude that cognitive dysfunction is common in patients many years after clinically isolated optic neuritis. Cognitive dysfunction was found even in patients who had no apparent demyelinating lesions on follow-up MRI.

Pathogenesis of autoimmune diseases: antibodies against transglutaminase, peptidylarginine deiminase and protein-bound citrulline in primary Sjögren's syndrome, multiple sclerosis and Alzheimer's disease.

Coeliac disease (CD) is becoming a model for understanding the pathogenesis of autoimmune disorders. In CD, antibodies against transglutaminase 2 (TG2) and specific residues of gliadins have been identified. A similar situation is seen in rheumatoid arthritis (RA) with both anti-citrullinated protein antibodies (ACPA) and auto-antibodies against the citrullinating enzyme, peptidylarginine deiminase (PAD). Previously, we have suggested that a complex between an enzyme and its modified substrate constitutes the neoantigen in autoimmune diseases. Our hypothesis is challenged by findings in patients of primary Sjögren's syndrome (pSS) who do not express ACPA, but who have been reported to carry anti-PAD. The aims of our investigation were to reproduce the study claiming the presence of anti-PAD in pSS and screen for ACPA and antibodies against TG2 and PAD in pSS (n = 78), multiple sclerosis (MS) (n = 85) and Alzheimer's disease (AD) (n = 79) using ELISA. With blood donors (n = 100) as controls, no increased occurrence of autoantibodies was found among the patient groups tested. Contrary to what has been published previously, patients with pSS do not express anti-PAD. The hypothesis of a complex between an enzyme and its modified substrate constituting the neoantigen in autoimmune diseases is still valid. The prevalence of anti-PAD, anti-TG2 and ACPA is comparatively restricted. PAD and TG2 do not seem to be involved directly in autoimmune mechanisms in pSS, MS or AD.

The role of MRI of the brain and spinal cord, and CSF examination for the diagnosis of primary progressive multiple sclerosis.

The clinical applicability of the revised McDonald diagnostic criteria of primary progressive multiple sclerosis (PPMS) was assessed in 17 patients with a longstanding PPMS diagnosis (mean 15 years). All patients were re-evaluated with clinical examinations, magnetic resonance imaging (MRI) of the brain and the spinal cord, extensive laboratory tests, and 12 patients underwent cerebrospinal fluid (CSF) examination. No diagnosis more likely than PPMS was disclosed. All patients had brain and spinal cord lesions on MRI. In 15 patients the brain lesions and in 14 the spinal cord lesions fulfilled the revised McDonald criteria for positive scans. No contrast-enhancing lesion was observed despite administration of triple doses of gadolinium. In total, 12 patients fulfilled the revised McDonald MRI criteria for PPMS. Of the remaining five patients who incompletely fulfilled the revised MRI criteria, all had CSF findings supporting the diagnosis PPMS. Thus, CSF analysis was required in addition to MRI in about one-third of the patients to establish the diagnosis of PPMS.

A follow-up study of Nordic multiple sclerosis candidate gene regions.

In this study, the results from three Nordic linkage disequilibrium screens in multiple sclerosis (MS) were investigated, in a new sample set of 314 Nordic MS trios from Denmark, Norway, Sweden and Iceland. Among 30 non-HLA and two HLA microsatellite markers individually genotyped, eight markers displayed distorted transmission with uncorrected P-value<0.05, ranked in this order: D6S2443 (6p21.32, HLA class II) (P corrected=0.01), D2S2201 (2p24), D19S552 (19q13), D3S3584 (3q21), D17S975 (17q11), D1S2627 (1p22), D6S273 (6p21.33, HLA class III) and D12S1051 (12q23). These non-HLA regions need further investigation as possible MS candidate gene regions in our population.

Health-related quality of life in secondary progressive multiple sclerosis.

Common disability scales in multiple sclerosis (MS) are often weighted towards physical disability. Non-motor symptoms such as depression, fatigue and pain substantially influence wellbeing in MS. Health-related quality of life (HRQoL) measures the broader impact of MS and might indicate less obvious disease burdens. We analysed HRQoL, using the Nottingham Health Profile Part I (NHP-I), among 345 secondary progressive MS (SPMS) patients participating in a randomized trial of interferon-beta1a (IFN-beta1a), 22 mug subcutaneously weekly, or matching placebo. The results did not reveal any beneficial effect of IFN-beta1a in any outcome measure. NHP-I sub- and sum scores were compared for 217 population controls and correlated with demographic and clinical disease variables. SPMS patients had lower NHP-I sum and all subscores than the controls. Patients experiencing disease progression reported worse NHP-I sum scores. Increased fatigue, Expanded Disability Status Scale (EDSS) and Arm Index scores were independently associated with reduction in several NHP-I subscores. SPMS patients had significantly lower HRQoL than controls and physical disability (EDSS and Arm Index), disease progression and fatigue strongly influenced this. MS.

Long-term subcutaneous interferon beta-1a therapy in patients with relapsing-remitting MS.

OBJECTIVE: To conduct systematic long-term follow-up (LTFU) of patients in the Prevention of Relapses and Disability by Interferon beta-1a Subcutaneously in Multiple Sclerosis (PRISMS) study to provide up to 8 years of safety, clinical and MRI outcomes on subcutaneous (s.c.) interferon (IFN) beta-1a in relapsing-remitting multiple sclerosis (RRMS). METHODS: The original cohort of 560 patients was randomized to IFNbeta-1a, 44 or 22 microg three times weekly (TIW) or to placebo; after 2 years, patients on placebo were rerandomized to active treatment and the blinded study continued for a further 4 years. The LTFU visit was scheduled 7 to 8 years after baseline. RESULTS: LTFU was attended by 68.2% of the original PRISMS study cohort (382/560 patients). 72.0% (275/382) were still receiving IFNbeta-1a s.c. TIW. Patients originally randomized to IFNbeta-1a 44 microg s.c. TIW showed lower Expanded Disability Status Scale progression, relapse rate and T2 burden of disease up to 8 years compared with those in the late treatment group. Brain parenchymal volume did not show differences by treatment group. Overall, 19.7% of patients progressed to secondary progressive MS between baseline and LTFU (75/381). No new safety concerns were identified and treatment was generally well tolerated. CONCLUSIONS: Despite the limitations inherent in any long-term study (for example, potential differences between returning and nonreturning patients), these results indicate that patients with relapsing-remitting multiple sclerosis can experience sustained benefit over many years from early interferon beta-1a subcutaneous therapy three times weekly compared with patients whose treatment is delayed. This effect was more apparent in the patients receiving the higher dose.

Pregnancy outcomes during treatment with interferon beta-1a in patients with multiple sclerosis.

BACKGROUND: Although patients with multiple sclerosis (MS) are advised to stop interferon (IFN) beta-1a therapy before becoming pregnant, some patients become pregnant while on treatment. METHODS: We examined individual patient data from eight clinical trials with IFNbeta-1a. RESULTS: Of 3,361 women in the studies, 69 pregnancies were reported, of which 41 were patients receiving (or who had stopped receiving within 2 weeks prior to conception) IFNbeta-1a (in utero exposure group), 22 were patients who discontinued IFNbeta-1a treatment more than 2 weeks before conception (previous exposure group), and six were patients receiving placebo. The 41 in utero exposure pregnancies resulted in 20 healthy full-term infants, one healthy premature infant, nine induced abortions, eight spontaneous abortions, one fetal death, and one congenital anomaly (hydrocephalus). One patient was lost to follow-up. The 22 previous exposure pregnancies resulted in 20 full-term healthy infants, one healthy premature infant, and one birth-related congenital anomaly (Erb palsy). CONCLUSIONS: The majority (21/31) of pregnancies that had the potential to go to full term produced healthy infants. The rate of spontaneous abortion was higher, but not significantly so, in the in utero exposure group compared to general population estimates. Until more exposure data become available, patients remain advised to stop IFNbeta therapy before becoming pregnant.

Neutralizing antibodies and efficacy of interferon beta-1a: a 4-year controlled study.

OBJECTIVE: To determine the incidence and clinical significance of neutralizing antibody (NAb) formation in patients with relapsing multiple sclerosis (MS) who participated in the European Interferon Beta-1a IM Dose-Comparison Study. METHODS: Patients were randomized to treatment with interferon beta-1a (IFNbeta-1a) 30 microg or 60 microg IM once weekly for up to 4 years. Serum samples obtained at baseline and every 3 months thereafter were screened for the presence of IFN binding antibodies by ELISA. Patients whose results were seropositive on ELISA were screened for the presence of NAbs using an antiviral cytopathic effect assay. Patients were considered to be positive for NAbs (NAb+) if the baseline NAb titer was 0 and two or more consecutive postbaseline titers were > or = 20. Patients were considered to be negative for NAbs (NAb-) if the baseline NAb titer was 0 and all postbaseline NAb titers were < 5. RESULTS: The proportion of patients who became NAb+ was lower in patients who received 30 microg of IFNbeta-1a than in those who received 60 microg (7/400 [1.8%] vs 19/395 [4.8%]; p = 0.02). The mean time to NAb+ status was 14.5 +/- 6.2 months. Compared with patients who remained NAb-, NAb+ patients showed the following: higher relapse rates from months 12 to 48 (p = 0.04), higher rate of mean change (worsening) in Expanded Disability Status Scale score from baseline to month 48 (p = 0.01), greater number of T1 gadolinium-enhanced lesions at months 24 and 36 (p = 0.02 and 0.03), and greater accrual of new or enlarging T2 lesions from month 12 to months 24 and 36 (p = 0.05 and 0.09). CONCLUSIONS: Neutralizing antibodies (NAbs) to interferon beta-1a (IFNbeta-1a), as observed with other IFNbetas used in the treatment of multiple sclerosis, reduce the therapeutic benefits measured by relapses and MRI activity. Data from this study also suggest NAbs to IFNbeta-1a reduce treatment benefits as measured by change in Expanded Disability Status Scale score.

Treatment with laquinimod reduces development of active MRI lesions in relapsing MS.

BACKGROUND: Laquinimod is a novel immunomodulatory substance developed as an orally available disease modifying treatment in multiple sclerosis (MS). The purpose of this study was to evaluate safety, tolerability, and efficacy on MRI lesions of two different doses of laquinimod compared with placebo in patients with relapsing MS. METHODS: In this multicenter, double-blind, randomized trial, patients with relapsing MS received 0.1 mg or 0.3 mg laquinimod or placebo as three daily tablets for 24 weeks. Gadolinium-enhanced brain MRI scans were performed at screening, every eighth week during treatment, and 8 weeks after end of treatment. The primary efficacy variable was the cumulative number of active lesions over 24 weeks. Safety measures included adverse events, physical examination, and laboratory variables. RESULTS: Of 256 screened patients, 209 were randomized (67 to 74 patients per group) in 20 centers. There was a significant difference between laquinimod 0.3 mg and placebo for the primary outcome measure (mean cumulative number of active lesions reduced by 44%). In the subgroup of patients with at least one active lesion at baseline the reduction was slightly more pronounced (52%). No differences with respect to clinical variables (relapses, disability) were found. The safety profile was favorable; there were no clinical signs of undesired inflammatory manifestations. CONCLUSION: Oral laquinimod in a dosage of 0.3 mg daily was well tolerated and effective in suppressing development of active lesions in relapsing multiple sclerosis.

Comparative tolerance of IFN beta-1a regimens in patients with relapsing multiple sclerosis. The EVIDENCE study.

The EVIDENCE study was a direct comparative study of two dose regimens of interferon (IFN) beta-1a used in the treatment of relapsing-remitting multiple sclerosis (RRMS): 30 mcg intramuscularly once weekly (qw; n=338) and 44 mcg subcutaneously three times weekly (tiw; n=339). The study continued for an average of 64 weeks. The safety population consisted of all patients receiving at least one dose of study drug. Clinical assessments occurred every 4 weeks for 24 weeks and then every 12 weeks. Blood tests for safety were taken at baseline and at weeks 4 and 12, and every 12 weeks thereafter. Overall adverse events were more common with the 44 mcg tiw regimen (p=0.007), and were due predominantly to differences in injection-site reactions. The majority of adverse events were rated mild by investigators. Hepatic and haematological adverse events and asymptomatic laboratory abnormalities were more common with 44 mcg tiw (p<0.001),with no difference seen for severe events. Flu-like symptoms were more common with 30 mcg qw (p=0.031), were more severe and persisted for longer. Serious adverse events were comparable for both groups, as were drug discontinuations. In conclusion, although adverse events were more common with high-dose, high-frequency IFN therapy, differences were primarily for mild events and did not affect treatment adherence. Based on superior clinical and magnetic resonance imaging outcomes over an average of 64 weeks, coupled with modest safety differences, the risk-benefit ratio for IFN therapy in RRMS favours the 44 mcg tiw regimen over this period of time.

Multicentre, randomised, double blind, placebo controlled, phase III study of weekly, low dose, subcutaneous interferon beta-1a in secondary progressive multiple sclerosis.

OBJECTIVE: Interferon (IFN) beta has repeatedly shown benefit in multiple sclerosis (MS) in reducing the rate of relapse, the disease activity as shown with magnetic resonance imaging and, to some degree, the progression of disability; however, it is unknown how much the therapeutic response depends on the dose, the subgroup involved, and the disease stage. This multicentre, double blind, placebo controlled study explored the dose-response curve by examining the clinical benefit of low dose IFN beta-1a (Rebif), 22 micro g subcutaneously once weekly, in patients with secondary progressive MS. METHODS: A total of 371 patients with clinically definite SPMS were randomised to receive either placebo or subcutaneous IFN beta-1a, 22 micro g once weekly, for 3 years. Clinical assessments were performed every 6 months. The primary outcome was time to sustained disability, as defined by time to first confirmed 1.0 point increase on the Expanded Disability Status Scale (EDSS). Secondary outcomes included a sensitive disability measure and relapse rate. RESULTS: Treatment had no beneficial effect on time to confirmed progression on either the EDSS (hazard ratio (HR) = 1.13; 95% confidence interval (CI) 0.82 to 1.57; p = 0.45 for 22 micro g v placebo) or the Regional Functional Status Scale (HR = 0.93; 95% CI 0.68 to 1.28; p = 0.67). Other disability measures were also not significantly affected by treatment. Annual relapse rate was 0.27 with placebo and 0.25 with IFN (rate ratio = 0.90; 95% CI 0.64 to 1.27; p = 0.55). The drug was well tolerated with no new safety concerns identified. No significant gender differences were noted. CONCLUSIONS: This patient population was less clinically active than SPMS populations studied in other trials. Treatment with low dose, IFN beta-1a (Rebif) once weekly did not show any benefit in this study for either disability or relapse outcomes, including a subgroup with preceding relapses. These results add a point at one extreme of the dose-response spectrum of IFN beta therapy in MS, indicating that relapses in this phase may need treatment with higher doses than in the initial phases.

Genes in the HLA class I region may contribute to the HLA class II-associated genetic susceptibility to multiple sclerosis.

In order to analyze whether loci in the human leukocyte antigen (HLA) class I region may contribute to the HLA class II-associated genetic susceptibility to multiple sclerosis (MS), we examined selected microsatellite markers in 177 Nordic sib-pair families, 222 British sib-pair families, 323 sporadic Norwegian MS patients and 386 Norwegian controls. All samples were, in addition, genotyped for the HLA-DR DQ haplotype, and the Norwegian case-control samples were also typed for HLA-A and -B loci. In the Norwegian sporadic MS patients association was seen with HLA-A, HLA-B, and with the D6S265 marker, located 100 kb centromeric to HLA-A. Associations with HLA-A and D6S265 loci were also suggested when restricting the analysis to HLA-DR15 haplotypes. In the sib-pair data a similar trend was seen with marker D6S265. Higher genotypic relative risk (GRR) was found for individuals who carry both HLA-DR15 and -A3 (GRR = 15), compared to those who carry only HLA-DR15 (GRR = 7), only HLA-A3 (GRR = 3) or none of these alleles (GRR = 1). The highest risk was conferred by a combination of HLA-DR15 and -A3 (odds ratio (OR) = 5.2). These results suggest that HLA-A or a gene in linkage disequilibrium with it may contribute to the HLA class II-associated genetic susceptibility to MS.

No evidence for genetic linkage between development of multiple sclerosis and components of the IFN system and the JAK-STAT pathway.

Multiple sclerosis (MS) is an inflammatory, demyelinating disease of the central nervous system (CNS). Several observations suggest that the interferon system may be of interest in the study of MS development To investigate whether polymorphism in components of the IFN system and the JAK-STAT pathway influence susceptibility to MS, we performed a linkage analysis between polymorphic loci in or close to the IFN gamma, IFN gamma receptor, IFN alpha/beta receptor, JAK 1, STAT 1 and STAT 3 genes in 27 Swedish families with at least two members having MS. Tests for transmission disequilibrium and nonparametric linkage analysis gave negative results. We found no evidence for linkage between MS and any of these loci.

Factors influencing analysis of prolyl endopeptidase in human blood and cerebrospinal fluid: increase in assay sensitivity.

Prolyl endopeptidase (EC 3.4.21.26) (PEP) is present in nearly all investigated mammalian cells and biological fluids and might be involved in the degradation of physiologically important neuropeptides. To be able to investigate the variation of PEP in blood and cerebrospinal fluid (CSF) in human disease, the factors influencing analysis of PEP in these body fluids must be determined. The purpose of the present work was to study the influence of storage conditions, anticoagulation additives, freezing and thawing and substrate solvent on determination of PEP in blood plasma/serum and CSF. It was found that the PEP activity was about 10% higher in plasma (with EDTA and heparinate for anticoagulation) than in serum. Storage at room temperature (20 degrees C) caused a rapid decline in enzyme activity, which was smaller but still considerable at 4 degrees C. Storage at -20 degrees C and -70 degrees C did not decrease the PEP activity. Freezing and thawing of plasma/serum samples showed that the first freeze-thawing cycle produced a 20% reduction in enzyme activity but little further decrease was observed during subsequent cycles of freeze-thawing. In conclusion, PEP activity should preferably be measured within one hour after sampling using EDTA- or heparinate plasma. For long-term storage, samples should be immediately frozen and stored at -20 degrees C or colder. The selection and amount of the organic solvent used to dissolve the fluorogenic substrate strongly influenced the sensitivity of the assay. By developing an optimal solvent system an increase in assay sensitivity of about 400% could be obtained, which for the first time allowed measurement of the PEP activity in CSF.

A randomized, double-blind, dose-comparison study of weekly interferon beta-1a in relapsing MS.

BACKGROUND: Interferon beta-1a (IFNbeta-1a; Avonex) is effective for the treatment of relapsing MS; however, the optimal dose of IFNbeta-1a is not known. OBJECTIVE: To determine whether IFNbeta-1a 60 micro g IM once weekly is more effective than IFNbeta-1a 30 micro g IM once weekly in reducing disability progression in relapsing MS. METHODS: In a double-blind, parallel-group, dose-comparison study, 802 patients with relapsing MS from 38 centers in Europe were randomized to IFNbeta-1a 30 micro g (n = 402) or 60 micro g (n = 400) IM once weekly for >/=36 months. The primary endpoint was disability progression, defined as time to a sustained increase of >/=1.0 point on the Expanded Disability Status Scale (EDSS) persisting for 6 months. Additional endpoints included relapses, MRI, safety, immunogenicity, and subgroup analyses of disability progression. RESULTS: Both groups showed equal rates of disability progression (hazard ratio, 0.96; 95% CI, 0.77 to 1.20; p = 0.73). In both groups the proportion of subjects with progression of disability by 36 months estimated from Kaplan-Meier curves was 37%. No dose effects were observed on any of the secondary clinical endpoints. Only one MRI measure at one time point, number of new or enlarging T2 lesions at month 36 compared with month 24, showed a difference favoring the 60- micro g dose. Both doses were well tolerated; however, slightly higher incidences of flulike symptoms and muscle weakness were observed in the 60- micro g group. The incidences of neutralizing antibodies (titers >/= 20) were 2.3% in the 30- micro g group and 5.8% in the 60- micro g group. CONCLUSION: There was no difference between IFNbeta-1a 30 micro g and 60 micro g IM in clinical or MRI measures.

A genome-wide screen for linkage in Nordic sib-pairs with multiple sclerosis.

Genetic factors influence susceptibility to multiple sclerosis but the responsible genes remain largely undefined, association with MHC class II alleles being the only established genetic feature of the disease. The Nordic countries have a high prevalence of multiple sclerosis, and to further explore the genetic background of the disease, we have carried out a genome-wide screen for linkage in 136 sibling-pairs with multiple sclerosis from Denmark, Finland, Norway and Sweden by typing 399 microsatellite markers. Seventeen regions where the lod score exceeds the nominal 5% significance threshold (0.7) were identified-1q11-24, 2q24-32, 3p26.3, 3q21.1, 4q12, 6p25.3, 6p21-22, 6q21, 9q34.3, 10p15, 10p12-13, 11p15.5, 12q21.3, 16p13.3, 17q25.3, 22q12-13 and Xp22.3. Although none of these regions reaches the level of genome-wide significance, the number observed exceeds the 10 that would be expected by chance alone. Our results significantly add to the growing body of linkage data relating to multiple sclerosis.

International consensus statement on the use of disease-modifying agents in multiple sclerosis.

OBJECTIVE: To provide recommendations on the use of disease-modifying agents in the management of multiple sclerosis (MS) and to ensure that treatment will be available to those patients who may benefit. METHODS: An initial draft of the consensus statement was prepared by the Steering Committee and amended in the light of written comments from a group of MS specialists. At a subsequent workshop, the wording of the consensus statement was discussed, modified if necessary, and the participants indicated their level of support using an electronic voting system. A new draft of the statement was then sent to a much larger group of international opinion leaders in MS for further comment. RESULTS: A number of statements were agreed, which outline the criteria for consideration of disease-modifying therapy for MS and recommendations for treatment. Each statement was accepted completely, or with only minor reservations by 95% or more of those present at the workshop. CONCLUSIONS: Periodic reviews and modifications to the statement will be required, as new approaches to the treatment of MS and other therapeutic agents become available.

Serological differences in monozygotic twin pairs discordant for multiple sclerosis.

OBJECTIVES: The etiology of MS is unknown but genetic factors are supported by a high concordance in twins. Geographic distribution and migration studies indicate, however, the importance of environmental factors. MATERIAL AND METHODS: We studied 3 pairs of genetically identical twins who had shared the same environment but were discordant for MS. Serum samples were assayed for antibodies against 21 viruses, 4 bacteria and Toxoplasma gondii. RESULTS AND CONCLUSION: No common factor present only in the affected twins was identified but differences were found in serum titers against some neurotropic microorganisms. In general the serum titers were strikingly similar in the twins, indicating no major disturbances of the humoral immune system in MS.

The T cell regulator gene SH2D2A contributes to the genetic susceptibility of multiple sclerosis.

The T cell specific adapter protein (TSAd) encoded by the SH2D2A gene is involved in the control of T cell activation. The gene is located in the 1q21 region, which has been implicated in susceptibility to experimental allergic encephalomyelitis in the mouse. We therefore evaluated whether a polymorphic GA repeat (GA(13)-GA(33)) within the promoter region of the SH2D2A gene shows association to multiple sclerosis (MS). The frequency of the short alleles GA(13-16) was increased among 313 Norwegian MS patients compared to 277 healthy controls (0.332 vs 0.249, OR 1.5, Pc = 0.03). Transmission disequilibrium analysis in 146 Scandinavian families with at least two affected sibs showed increased transmission of GA(16) to MS patients. No linkage or association of MS to four genetic markers flanking the SH2D2A gene was observed. After activation of naive CD4(+) T cells, T cells homozygous for MS associated short alleles displayed lower level of TSAd ex vivo than T cells carrying at least one long allele, which were not associated to MS. Since the SH2D2A protein modulates T cell activation, this may be a mechanism for how short SH2D2A alleles confer susceptibility to develop MS.

No linkage or association of the nitric oxide synthase genes to multiple sclerosis.

Multiple sclerosis (MS) is a chronic inflammatory disease of the central nervous system (CNS) of unknown etiology. Nitric oxide (NO) is a free radical that participates in a variety of biological processes. It is an important mediator in the immune response. Several studies indicate involvement of NO in the pathogenesis of MS. We studied five markers within the three NO synthase genes with regards to susceptibility and disease course in 156 affected sib-pairs and in 96 "benign" and 96 "severe" definite MS patients and 148 controls. We found no significant association or evidence for linkage in our data sets.