In the randomized, placebo-controlled, physician-blinded Canadian cooperative trial of cyclophosphamide and plasma exchange, neither active treatment regimens (group I: i.v. cyclophosphamide and prednisone; group II: weekly plasma exchange, oral cyclophosphamide, and prednisone) were superior to placebo (group III: sham plasma exchange and placebo medications) using the blinded, evaluating neurologists' assessments of disease course (primary analysis). All patients were examined by both a blinded and an unblinded neurologist at each assessment in this trial. We compared the blinded and unblinded neurologists' judgment of treatment response and analyzed the clinical behavior of patients who correctly guessed their treatment. The unblinded (but not the blinded) neurologists' scores demonstrated an apparent treatment benefit at 6, 12, and 24 months for the group II patients (not group I or placebo; p < 0.05, two-tailed). There were no significant differences in the time to treatment failure or in the proportions of patients improved, stable, or worse between the group II and group III patients who correctly guessed their treatment assignments and those who did not. Physician blinding prevented an erroneous conclusion about treatment efficacy (false positive, type 1 error).

The decisive conclusions to be drawn from the available epidemiological data, mostly geography and prevalence, of MS are: (1) a north-south (as well as west-east in the United States) gradient exists independent of genetic/racial factors; (2) major differences in prevalence occur in the absence of latitude differences; (3) individuals from the same ethnic derivation have either similar prevalence rates or very different prevalence rates in widely separated geographical areas and (4) specific resistant isolates are shown to exist regardless of latitude. Existing information leads to the almost inescapable conclusion that the epidemiology of MS cannot be explained by any single known environmental or genetic factor(s) in isolation. A combination of a heterogeneous distribution of both genetic and environmental factors appears to be required to explain the available data on MS.

Major histocompatibility complex (MHC) class II molecules are central to adaptive immune responses and maintenance of self-tolerance. Since the early 1970s, the MHC class II region at chromosome 6p21 has been shown to be associated with a remarkable number of autoimmune, inflammatory and infectious diseases. Given that a full explanation for most MHC class II disease associations has not been reached through analysis of structural variation alone, in this review we examine the role of genetic variation in modulating gene expression. We describe the intricate architecture of the MHC class II regulatory system, indicating how its unique characteristics may relate to observed associations with disease. There is evidence that haplotype-specific variation involving proximal promoter sequences can alter the level of gene expression, potentially modifying the emergence and expression of key phenotypic traits. Although much emphasis has been placed on cis-regulatory elements, we also examine the role of more distant enhancer elements together with the evidence of dynamic inter- and intra-chromosomal interactions and epigenetic processes. The role of genetic variation in such mechanisms may hold profound implications for susceptibility to common disease.

BACKGROUND

Results from the Canadian Collaborative Project on Genetic Susceptibility to Multiple Sclerosis (MS)-Phase 1 (CCPGSMS-Phase 1) together with other family data published since 1982 have led to the following conclusions about the etiology of MS: (i) genetic and non-genetic (environmental) factors are involved in the etiology of MS on a population basis; (ii) the familial aggregation of MS is genetic; (iii) maternal factors do not influence the risk for siblings to develop MS; and (iv) MS appears to be oligogenic. The present paper describes the rationale and methodology for the CCPGSMS-Phase 2.

METHODS

The CCPGSMS-Phase 2 is a nation-wide collaborative effort involving all the 15 Canadian MS clinics. A series of structured questionnaires is administered to MS index cases, spouse controls and mothers of index cases and spouse controls (if available) by trained interviewers. Blood samples are taken for molecular genetic studies. This national effort is coordinated by the MS Clinics in Vancouver and London.

RESULTS

The CCPGSMS-Phase 2 is in progress so specific results are not available. The study is designed to (i) increase the database for genetic epidemiological/molecular genetic research and (ii) gather population-based data to further our understanding of the non-genetic factors in the etiology of MS.

CONCLUSIONS

It is anticipated that the results from this study will impact on the eventual prevention, cure and treatment of MS.

OBJECTIVE

To identify the cause of hypokalemic periodic paralysis (HOKPP) in a family whose disease is not caused by a mutation in the dihydropyridine-sensitive (DHP) receptor alpha1-subunit gene (CACNA1S).

BACKGROUND

Hypokalemic periodic paralysis is primarily caused by mutations within CACNA1S. Genetic heterogeneity for HOKPP has been reported, but no other locus has been identified.

METHODS

Single-stranded conformational polymorphism (SSCP) analysis and PCR direct sequencing were used to screen the skeletal muscle alpha1-sodium channel gene (SCN4A) for a mutation in our family.

RESULTS

SSCP analysis showed an abnormally migrating conformer in exon 12. Direct sequencing of the conformer showed a guanine to adenine transition at position 2006 in the cDNA sequence; this results in an amino acid substitution of a highly conserved arginine (Arg) to histidine (His) at position 669. This sequence alteration segregated only with the affected members of the kindred and was not found in a panel of 100 DNA samples from healthy controls. The amino acid substitution alters the outermost positive charge in the membrane spanning segment DII/S4, which is involved in voltage sensing.

CONCLUSIONS

The first arginine in DII/S4 and in DIV/S4 within the skeletal muscle sodium channel and the L-type calcium channel genie CACNA1S appear to be critical for normal function. In all four cases, Arg to His mutations result in a disease phenotype. The identification of a mutation within the skeletal muscle sodium channel resulting in hypokalemic periodic paralysis represents a novel finding.

BACKGROUND

T2-weighted and gadolinium enhanced T1-weighted MRI scans measure plaque burden and breakdown of the blood-brain barrier, respectively, in multiple sclerosis (MS) lesions. These have become widely used outcome measures for monitoring disease activity in clinical trials and clinical practice. However, their use as surrogates or biomarkers for disability and relapses, key clinical outcome measures, has remained incompletely validated.

METHODS

In a clinical trial database comprised of 31 relapsing-remitting and secondary progressive MS trial placebo groups, we assessed relationships between 1) T2 lesion load (TLL) change and disability change and 2) gadolinium enhancement of MS lesions and on-study relapses with univariate and multivariate analyses.

RESULTS

In relapsing-remitting MS, TLL change (n = 223) made no independent contribution to predicting change in disability from baseline to trials' end. Similarly, inclusion of gadolinium enhancing lesions (n = 170) into multivariate models did not independently contribute to the predictive value for on-trial relapses. In secondary progressive MS, a small effect of TLL was found for disability change (n = 355) but in multivariate analysis this accounted for less than 5% of the variance in end-of-trial disability. Results were replicated in independent datasets, more than doubling effective sample sizes.

CONCLUSIONS

MRI measures widely used in trials of relapsing-remitting and progressive multiple sclerosis add little if anything independently to the clinically relevant relapse and disability outcomes. These results reemphasize the importance of validating potential surrogate markers against clinical measures and highlight the need for better MRI markers of disease activity and progression.

BACKGROUND

French farmers and their families constitute an informative population to study multiple sclerosis (MS) prevalence and related epidemiology. We carried out an ecological study to evaluate the association of MS prevalence and ultraviolet (UV) radiation, a candidate climatologic risk factor.

METHODS

Mean annual and winter (December-March) UVB irradiation values were systematically compared to MS prevalence rates in corresponding regions of France. UVB data were obtained from the solar radiation database (SoDa) service and prevalence rates from previously published data on 2,667 MS cases registered with the national farmer health insurance system, Mutualité Sociale Agricole (MSA). Pearson correlation was used to examine the relationship of annual and winter UVB values with MS prevalence. Male and female prevalence were also analyzed separately. Linear regression was used to test for interaction of annual and winter UVB with sex in predicting MS prevalence.

RESULTS

There was a strong association between MS prevalence and annual mean UVB irradiation (r = -0.80, p < 0.001) and average winter UVB (r = -0.87, p < 0.001). Both female (r = -0.76, p < 0.001) and male (r = -0.46, p = 0.032) prevalence rates were correlated with annual UVB. Regression modeling showed that the effect of UVB on prevalence rates differed by sex; the interaction effect was significant for both annual UVB (p = 0.003) and winter UVB (p = 0.002).

CONCLUSIONS

The findings suggest that regional UVB radiation is predictive of corresponding MS prevalence rates and supports the hypothesis that sunlight exposure influences MS risk. The evidence also supports a potential role for gender-specific effects of UVB exposure.

Classifications of multiple sclerosis subtypes have been largely based on clinical phenomenology. Nevertheless, definitions of relapse, remission and progression have been imprecise. Recently an international consensus group, as part of a reclassification of disease subtypes, recommended dropping the term 'relapsing-progressive' (RP) and retaining the term 'progressive-relapsing' (PR) multiple sclerosis. The term 'RP' multiple sclerosis had been applied when the early course combined both relapses and progression and was believed to identify some patients with a worse than average outcome. The PR group consisted of patients with primary progressive disease who later in their course developed relapses. Since the terminology has been largely arbitrary, we have evaluated the validity of the terms 'RP' and 'PR' multiple sclerosis in the context of long-term outcome within a large population-based cohort of progressive multiple sclerosis patients seen at the London Multiple Sclerosis Clinic (Canada) between 1972 and 1984. Mean follow-up of the entire cohort was 25 years. Designation of RP multiple sclerosis did identify a more rapidly progressive subgroup. To realign these natural history data with consensus recommendations, these patients were reassigned to secondary progressive (SP) or to primary progressive (PP) multiple sclerosis, with progression defined as at least 1 year of progressive deterioration. PP multiple sclerosis patients with relapses after a year were designated as having PR multiple sclerosis. Relapses in primary progressive multiple sclerosis occurred in 27.8% of patients at some point even two to three decades after onset. In general these relapses were mild and remitting, but served to blur the distinction between progressive and relapsing-remitting disease. The long-term outcomes of time to Kurtzke disability scores (DSS) of 3, 6, 8 and 10 were compared among the progressive subtypes. Times to these disability end-points and to death were not different between PR and PP multiple sclerosis. Survival curves for progressive patients have been amended to incorporate the reassignment of PR multiple sclerosis patients into the PP group and the RP multiple sclerosis patients into the PP and SP subgroups. The time to reach DDS 3, 6, 8 and 10 for a population-based cohort of primary and secondary progressive patients resulting from the elimination of the categories of RP multiple sclerosis and PR multiple sclerosis has been established. These results provide justification for retaining only PP and SP multiple sclerosis as the subgroups of progressive disease.

One multiple sclerosis (MS) is diagnosed, important considerations often include life expectancy and the availability of life insurance. We designed a study specifically to examine life expectancy among MS clinic patients and analyzed the data using standard actuarial methods, both including and excluding suicides. The data show that severe MS disability, as measured by an Expanded Disability Status Score (EDSS) of greater than or equal to 7.5, is a major risk factor for death with case fatality ratios for this group of patients approaching 4 times the rate for controls. Conversely, excluding deaths by suicide, case fatality ratios for those with mild and moderate disability (EDSS less than or equal to 7.0) approach 1.4 times and 1.6 times for age- and sex-matched comparison groups. Life tables indicate that the overall life expectancy for MS is only about 6 to 7 years less than that for the "insured" population without MS.

BACKGROUND

Inferences about long-term effects of therapies in multiple sclerosis (MS) have been based on surrogate markers studied in short-term trials. Preventing progressive disability is the key therapeutic goal but there remains no validated definition for its measurement in a trial context. Meanwhile, MS trials continue to shorten and to depend on unvalidated surrogates. Since there have been no treatment claims for improving unremitting disability, worsening of disability in the placebo/control arm must occur for effectiveness on this outcome to be shown.

METHODS

We examined widely-used clinical surrogates of long-term disability progression in individual patients with MS within a unique database from the placebo arms of 31 randomized clinical trials.

RESULTS

Detection of treatment effects in secondary progressive MS trials is undermined by noise in disability measurement. Whereas existing measures can be partially validated in secondary progressive MS, this is not the case in relapsing-remitting MS. Here, examination of widely used definitions of treatment failure demonstrated that disability progression was no more likely than similarly defined improvement. Existing definitions of disease progression in short-term intervention trials in relapsing-remitting patients reflect random variation, measurement error, and remitting relapses.

CONCLUSIONS

Clinical surrogates of unremitting disability used in trials of relapsing-remitting multiple sclerosis cannot be validated. Trials have been too short or degrees of disability change too small to measure the key outcomes. These analyses highlight the difficulty in determining effectiveness of therapy in chronic diseases.

BACKGROUND

Evidence for efficacy of disease-modifying drugs in multiple sclerosis (MS) comes from trials of short duration. We report results from a 16 y, retrospective follow-up of the pivotal interferon beta-1b (IFNB-1b) study.

METHODS

The 372 trial patients were randomly assigned to placebo (n=123), IFNB-1b 50 microg (n=125) or IFNB-1b 250 microg (n=124) subcutaneously every other day for at least 2 y. Some remained randomised for up to 5 y but, subsequently, patients received treatment according to physicians' discretion. Patients were re-contacted and asked to participate. Efficacy related measures included MRI parameters, relapse rate, the Expanded Disability Status Scale, the Multiple Sclerosis Functional Composite Measure and conversion to secondary progressive MS.

RESULTS

Of the 88.2% (328/372) of patients who were identified, 69.9% (260/372) had available case report forms. No differences in outcome between original randomisation groups could be discerned using standard disability and MRI measures. However, mortality rates among patients originally treated with IFNB-1b were lower than in the original placebo group (18.3% (20/109) for placebo versus 8.3% (9/108) for IFNB-1b 50 microg and 5.4% (6/111) for IFNB-1b 250 microg).

CONCLUSIONS

The original treatment assignment could not be shown to influence standard assessments of long-term efficacy. On-study behaviour of patients was influenced by factors that could not be controlled with the sacrifice of randomisation and blinding. Mortality was higher in patients originally assigned to placebo than those who had received IFNB-1b 50 microg or 250 microg. The dataset provides important resources to explore early predictors of long-term outcome.

We used hypothetical entry criteria typical of those used in clinical therapeutic trials to determine the patients who would have been eligible among those followed in a clinic-based study of multiple sclerosis (MS) in London, Ontario, between 1972 and 1984. For these patients, we determined the observed frequency of deterioration by 1 point on the disability status scale (DSS) of Kurtzke, which is the most feasible and frequently used endpoint in clinical trials. We calculated the number of patients required for a randomized clinical trial to detect a significant result (alpha = 0.05) with 80% or 90% power based on the observed rate of deterioration. To assess the linearity of the DSS, we determined the frequency of progression and staying time at each level of the DSS. Overall the frequency of progression was lower and the staying times were longer at higher levels of disability. There was considerable intrapatient as well as interpatient variation in staying time. These data have major implications for the design and conduct of clinical therapeutic trials in MS.

Multiple sclerosis (MS) is a common inflammatory disease of the central nervous system unsurpassed for variability in disease outcome. A cohort of sporadic MS cases (n = 163), taken from opposite extremes of the distribution of long-term outcome, was used to determine the role of the HLA-DRB1 locus on MS disease severity. Genotyping sets of benign and malignant MS patients showed that HLA-DRB1*01 was significantly underrepresented in malignant compared with benign cases. This allele appears to attenuate the progressive disability that characterizes MS in the long term. The observation was doubly replicated in (i) Sardinian benign and malignant patients and (ii) a cohort of affected sibling pairs discordant for HLA-DRB1*01. Among the latter, mean disability progression indices were significantly lower in those carrying the HLA-DRB1*01 allele compared with their disease-concordant siblings who did not. The findings were additionally supported by similar transmission distortion of HLA-DRB1*04 subtypes closely related to HLA-DRB1*01. The protective effect of HLA-DRB1*01 in sibling pairs may result from a specific epistatic interaction with the susceptibility allele HLA-DRB1*1501. A high-density (>700) SNP examination of the MHC region in the benign and malignant patients could not identify variants differing significantly between the two groups, suggesting that HLA-DRB1 may itself be the disease-modifying locus. We conclude that HLA-DRB1*01, previously implicated in disease resistance, acts as an independent modifier of disease progression. These results closely link susceptibility to long-term outcome in MS, suggesting that shared quantitative MHC-based mechanisms are common to both, emphasizing the central role of this region in pathogenesis.

HLA-DRB1 is the major locus associated with risk for multiple sclerosis (MS). A recent genome-wide study showed three additional single-nucleotide polymorphisms (SNPs), within the IL2RA and IL7RA genes respectively, also to be associated with MS. Consistent association but lower significance was found for 13 other SNPs. In this study, we aimed to verify association of these SNPs with MS in 46 MS patients and 194 controls from a Dutch genetically isolated population. Apart from the human leukocyte antigen locus, the EVI5 gene on chromosome 1 was confirmed as a novel risk gene, with odds ratios (ORs) even higher than those from the MS Consortium (ORs 2.01 and 1.9; P=0.01). The risk effect of EVI5 was further validated for the general MS population in an independent set of 1318 MS patients from the Canadian Collaborative Project on the Genetic Susceptibility to MS. On the basis of the transmission disequilibrium testing, a weak but significant risk effect was observed (OR 1.15; P=0.03 and OR 1.15; P=0.04). This study confirms EVI5 as another risk locus for MS; however, much of the genetic basis of MS remains unidentified.

To determine the prevalence and nature of pain in multiple sclerosis, we evaluated by questionnaire, interview, and chart review 159 patients residing in Middlesex County and followed in the MS Clinic at University Hospital, London, Ontario, Canada. Eighty-eight patients (55%) had either an acute or chronic pain syndrome at some time during their disease. Fifteen patients (9%) with acute pain syndromes had episodes of paroxysmal tic-like pain diagnosed in seven as trigeminal neuralgia. Chronic pain syndromes, present for a mean duration of 4.9 years, occurred in 76 patients (48%) and included dysesthetic extremity pain (29%), back pain (14%), painful leg spasms (13%), and abdominal pain (2%). MS patients with pain were similar to the pain-free group in mean age of onset (34.0 versus 31.9 years), average duration of disease (13.3 versus 12.1 years), spinal cord involvement (97% for each group), and mean rating on Kurtzke Disability Status Scale (4.2 versus 3.5). They differed in sex ratio with a higher female-to-male ratio in the pain group (3:1 versus 1.4:1). Chronic pain is a common feature of well-established MS and is usually associated with a myelopathy. Therapy must be individualized for each specific pain syndrome.

OBJECTIVE

To assess the potential relationship of ultraviolet B radiation (UVB) and Epstein-Barr virus (EBV) exposure in explaining the period prevalence of multiple sclerosis (MS) in England.

METHODS

English national Hospital Episode Statistics covering all admissions to National Health Service hospitals in England in the 7 years from 1998 to 2005 were used to obtain the period prevalences of MS and infectious mononucleosis (IM) in England. The United States National Aeronautics and Space Administration's data on UVB intensity for England from the Nimbus 7 satellite was collected. The relationships among the 3 variables (MS prevalence, IM prevalence, and UVB intensity) were investigated.

RESULTS

The regression of MS against UVB intensity for all seasons had an r(2) of 0.61; when including the interaction of IM with seasonal UVB, the r(2) rose to 0.72.

CONCLUSIONS

UVB exposure and IM together can explain a substantial proportion of the variance of MS. The effect of UVB on generating vitamin D seems the most likely candidate for explaining its relationship with MS. There is a pressing need to investigate the role of vitamin D and EBV and how they might interact to influence MS risk to identify potential prevention strategies.

From a population-based sample of 15,504 patients attending Canadian multiple sclerosis (MS) clinics, we have determined the frequency of conjugal MS and have estimated the recurrence risk in offspring of such matings. Twenty-three MS cases were found among 13,550 spouses of study probands for a crude conjugal rate of 0.17% (95% CI of 0.10%-0.24%). Despite ascertainment bias that expectedly inflates this number, this is a frequency intermediate between the point prevalence (0.1%) and lifetime risk (0.2%) for the general population and close to an order of magnitude less than reported for half siblings reared apart (1.06%) from the same population. Six of the 49 offspring of conjugal pairs also had MS, and age conversion gives a rate similar to the concordance rate for Canadian monozygotic twins. However, this correction may not be appropriate in this special case. Despite an ascertainment bias in favor of recognizing affected spouses and a large population sample, the common environment in adulthood shared by spousal pairs could not be shown to increase the risk of conjugal MS. Although the high recurrence rate in offspring is similarly subject to an upward bias, the low risk for MS spouses and the high risk for offspring support other data indicating that familial risk is genetically determined. Furthermore, these results imply that susceptibility alleles are shared by unrelated individuals with the disease.

OBJECTIVE

The 16-Year Long-Term Follow-Up (LTF) to the pivotal interferon-beta-1b (IFNbeta-1b) trial explored clinical, MRI, cognitive, and patient-reported outcomes. Here, we report the safety assessments.

METHODS

In the pivotal study, 372 patients were randomized to placebo (n = 123), IFNbeta-1b 50 microg (n = 125), or IFNbeta-1b 250 microg (n = 124) subcutaneously every other day for up to 5 years. Sixteen years later, patients were asked to participate in this cross-sectional follow-up study. No particular therapy was stipulated during follow-up. Adverse events experienced since the pivotal trial were recorded. Neutralizing antibodies (NAbs) to IFNbeta-1b were measured using the myxovirus protein A induction assay. Statistical analyses were descriptive.

RESULTS

In total, 88.2% of patients (328/372) were identified. Some centers achieved 100% ascertainment, obviating selection bias. Treatment-related adverse events (e.g., leukopenia and liver and thyroid dysfunction) reported by LTF participants were in keeping with those previously established. Based on a follow-up period that includes 2,000 patient-years of IFNbeta-1b treatment, no new adverse events were observed that were associated with long-term IFNbeta-1b exposure. By LTF, NAbs to IFNbeta-1b disappeared in the majority (76%) of NAb-positive patients. NAb status during the pivotal study appeared to have no impact on long-term clinical and MRI outcomes. There were more deaths among patients assigned to placebo in the pivotal study (20/109 [18.3%]) compared with patients who received IFNbeta-1b 50 microg (9/108 [8.3%]) or IFNbeta-1b 250 microg (6/111 [5.4%]).

CONCLUSIONS

The results from the 16-Year Long-Term Follow-Up study support the long-term safety of interferon-beta-1b therapy in multiple sclerosis.

METHODS

This study provides Class III evidence that patients with relapsing-remitting MS taking IFNbeta-1b 50 microg or 250 microg subcutaneously every other day for up to 5 years, with subsequent unspecified treatment, have fewer deaths after 16 years of follow-up than similar patients on placebo for up to 5 years, with subsequent unspecified treatment (risk difference 11.5%, 95% confidence interval 4-19).

The decisive conclusions to be drawn from the geography and prevalence of MS are: (1) a north-south (as well as west-east in the United States) gradient exists independent from genetic/racial factors; (2) major differences in prevalence occur in the absence of difference in latitude; (3) individuals from the same ethnic derivation have either the similar prevalence or have very different prevalence rates in widely separated geographical areas, and (4) specific resistance isolates are shown to exist regardless of latitude. Existing prevalence information leads to the almost inescapable conclusion that the geography of MS cannot be explained by any single known environmental or genetic factor(s) in isolation. A combination of a heterogeneous distribution of both genetic and environmental factors appears to be required to explain the available data on MS and geography.

There has been increasing evidence that genetic factors have a role in determining susceptibility to MS. Re-examination of results from prevalence and migration surveys reveals that there remains considerable ambiguity in interpretation. Some patterns previously thought to decisively support environmental determination may still be explained, at least in part, on a genetic basis. It seems inescapable that MS is probably due to an interaction of genetic and environmental factors. It remains undetermined whether or not genes exist which are truly necessary for the development of the disease. Existing data are consistent with the notion that the study of MS susceptibility will parallel the findings in experimental models of spontaneous autoimmunity and that at very least, two genes and almost certainly several genes will be found to influence susceptibility and interact in as yet unknown ways. One of these loci appears to be the Class II MHC, although its role may be minor at the germ line level. Roles for the T-cell receptor alpha and beta loci appear to be minor and may even be non-existent in contributing to heritable susceptibility. We predict that additional loci will be identified which influence both susceptibility and outcome and will be more important. Furthermore, it is clear that the understanding of the contribution of individual susceptibility loci will continue to be difficult because of the constraints of human pedigree data. It is likely that further resolution of the questions posed above related to genetic susceptibility in MS will require multicenter collaboration.

Multiple Sclerosis (MS) is a common chronic central nervous system disease in young adults. Relative familial risk appears to be determined largely by genes while population risk is strongly influenced by environmental factors. This is supported by genetic epidemiological studies which also suggest an oligogenic inheritance of susceptibility. The HLA DRB1*1501, DQA1*0102, DQB1 0602 haplotype is associated with the disease but HLA contributes only modestly to overall susceptibility. The results of three genomic searches are concordant with the genetic epidemiology and imply a number of genes with interacting effects will be found. Importantly, no single region has been identified with a major influence on familial risk.

OBJECTIVE

We assessed the hypotheses that non-major histocompatibility complex multiple sclerosis (MS) susceptibility loci would be common to sporadic cases and multiplex families, that they would have larger effects in multiplex families, and that the aggregation of susceptibility loci contributes to the increased prevalence of MS in such families.

METHODS

A set of 43 multiplex families comprising 732 individuals and 211 affected subjects was genotyped for 13 MS candidate genes identified by genome-wide association. A control data set of 182 healthy individuals was also genotyped to perform a case-control analysis alongside the family-based pedigree disequilibrium association test, although this may have been underpowered.

RESULTS

An effect of the IL2RA and CD58 loci was shown in multiplex families as in sporadic MS. The aggregate of the IL2RA, IL7R, EVI5, KIAA0350, and CD58 risk genotypes in affected individuals from multiplex families was found to be notably different from controls (chi(2) = 112, p = 1 x 10(-22)).

CONCLUSIONS

Although differences between individual families can only be suggested, the aggregate results in multiplex families demonstrate effect sizes that are increased as compared with those reported in previous studies for sporadic cases. In addition, they imply that concentrations of susceptibility alleles at IL2RA, IL7R, EVI5, KIAA0350, and CD58 are partly responsible for the heightened prevalence of multiple sclerosis within multiplex families.

Fatigue occurs in a majority of patients with MS and is generally independent of measurable neurologic disability. Few options for treatment are available. We conducted a double-blind, placebo-controlled, crossover trial for each of two 4-week treatment periods. Forty-six eligible patients entered and five dropped out due to concurrent exacerbations. Nineteen patients (46.3%) experienced excellent or good relief of fatigue with pemoline, and eight patients (19.5%) with placebo (p = 0.06, Fisher's exact test). One-fourth of patients did not tolerate the drug well, and 7% had to discontinue pemoline during the study due to side effects. The most common side effects were anorexia, irritability, and insomnia. Pemoline may be an effective short-term treatment for fatigue associated with MS, but its adverse effects are not well tolerated by many patients.