HLA and prognosis in multiple sclerosis

HLA genotype as a marker of multiple sclerosis prognosis: A pilot study

OBJECTIVE

The identification of a biomarker with prognostic value is an unmet need in multiple sclerosis (MS). The objective of this study was to investigate a possible association of HLA genotype with disease status and progression in MS, based on comprehensive and sensitive clinical and magnetic resonance imaging (MRI) parameters to measure disease effects.

METHOD

A total of 118 MS patients (79 females, 39 males) underwent HLA typing. Patient MS status was assessed at two time points in a 2-year interval, based on clinical scores (including EDSS, MSSS, T25FW, 9-HPT, SDMT, BVMT, CVLT-II) and MRI evaluations. Quantitative brain MRI values were obtained for whole brain atrophy, FLAIR lesion volume change and number of new lesions using MSmetrix. Predefined HLA patient groups were compared as of disease status and progression. Global assessment was achieved by an overall t-statistic and assessment per measurement by a Welch test and/or Mann Whitney U test. The effects of multiple covariates, including age, gender and disease duration as well as scan parameters, were also evaluated using a regression analysis.

RESULTS

The HLA-A*02 allele was associated with better outcomes in terms of MSSS, EDSS and new lesion count (Welch test p-value<0.05). The HLA-B*07 and HLA-B*44 alleles showed a global negative effect on disease status, although none of the measurements reached significance (p-value<0.05). Results for the HLA-DRB1*15, HLA-DQB1*06 and HLA-B*08 alleles were inconclusive. The influence of the confounding variables on the statistical analysis was limited.

Factors associated with onset, relapses or progression in multiple sclerosis: A systematic review

Multiple sclerosis (MS) is a chronic disease of the central nervous system with an unidentified etiology. We systematically reviewed the literature on the possible risk factors associated with MS disease onset, relapses and progression from 1960 to 2012 by accessing six databases and including relevant systematic reviews, meta-analyses, case-control or cohort studies. The focus was on identifying modifiable risk factors. Fifteen systematic reviews and 169 original articles were quality assessed and integrated into a descriptive review. Best evidence, which included one or more prospective studies, suggested that lower exposure to sunlight and/or lower serum vitamin D levels were associated with an increased risk of developing MS onset and subsequent relapses, but a similar quality of evidence was lacking for disease progression. Prospective studies indicated that cigarette smoking may increase the risk of MS as well as accelerate disease progression, but whether smoking altered the risk of a relapse was largely unknown. Infections were implicated in both risk of developing MS and relapses, but data for progression were lacking. Specifically, exposure to the Epstein-Barr virus, particularly if this manifested as infectious mononucleosis during adolescence, was associated with increased MS risk. Upper respiratory tract infections were most commonly associated with an increase in relapses. Relapse rates typically dropped during pregnancy, but there was no strong evidence to suggest that pregnancy itself altered the risk of MS or affected long-term progression. Emerging research with the greatest potential to impact public health was the suggestion that obesity during adolescence may increase the risk of MS; if confirmed, this would be of major significance.

The outcome spectrum of multiple sclerosis: disability, mortality, and a cluster of predictors from onset

Interest in the long-term natural history of multiple sclerosis (MS) is being revived, as disability endpoints become increasingly important with the advent of highly efficacious long range but potentially harmful drugs. MS had an increasingly benign course, probably due to better assessment and changing diagnostic criteria. Incidence cohorts reduce inclusion bias, capturing both extreme benign and severe cases. We conducted a 50-year follow-up of an incidence cohort of Gothenburg residents with MS onset in 1950-1964 (n = 254; 212 with an initial relapsing-remitting course and 42 with a monophasic course, diagnostic criteria according to Poser). Patients were followed longitudinally until censoring, death, or study termination in 2012 and evaluated using Kaplan-Meier estimates and Cox regression analysis. Median time to secondary progression was 15 years. Median time to EDSS6 and EDSS7 was 26 and 48 years (n = 254), respectively. The cumulative risk of reaching EDSS6 was 50% at 55 years of age and 80% at 80 years of age (n = 212). A score based on a cluster of clinical features at onset predicted secondary progression, EDSS6, EDSS7, and EDSS10 (hazard ratio 1.6-2.3 per score unit for women, 0.99-1.49 for men). This score predicted the disease course during five decades indirectly, by predicting time to secondary progression. Age at onset predicted the course in men, with 3-6% yearly increase in the risk of reaching disability milestones. The present incidence cohort provided hard outcome data in untreated patients over several decades.

From the Gothenburg cohort to the Swedish multiple sclerosis registry

An overview of prevalence and incidence studies performed in Swedish centres is provided, showing improving coverage and methodology, notably the development in Gothenburg of the representative incidence cohort design. A common database for major Swedish centres was established in 1995, implementing the terminology of predictors from the Gothenburg cohort. By 2001, these databases were merged into the web-based national multiple sclerosis (MS) registry, which has had an ever-increasing coverage, although with still moderate data density. The registry now contains records on 13,000 Swedish patients with MS. It has the status of a national quality registry and exerts nation-wide pharmacological surveillance. In addition, it has been, and is being, used in nearly 100 scientific studies, including large epidemiological and genetic projects.

Genetics for understanding and predicting clinical progression in multiple sclerosis

INTRODUCTION

Multiple sclerosis (MS) is a dys-immune disease of the central nervous system with highly variable and unpredictable long-term outcome.

STATE OF THE ART

In the early 1970s association between HLA alleles and MS was established. Very recently, the power of Genome Wide Association Studies (GWAS) enabled the identification of several loci involved in immune functions as genetic risk factors in MS. Recent data suggest that common genetic variations might modulate the clinical phenotype of MS through a regulation of key pathophysiological pathways.

PERSPECTIVES

Identification of modifier genes might offer an opportunity to explore new relevant therapeutic targets and early prognostic markers. To date, studies of modifier genes in MS are numerous but results are still unclear. This research field may now benefit from large cohorts of patients available for association studies.

CONCLUSION

In this context, we propose a review of epidemiological and association studies of genetic modifying effect in MS.

HLA-DRB1: genetic susceptibility and disability progression in a Spanish multiple sclerosis population

BACKGROUND AND OBJECTIVE

The association of HLA-DRB1*15 with susceptibility to multiple sclerosis (MS) has been consistently reported although its effect on the clinical phenotype is still controversial. The objectives of this study are to investigate the influence of the HLA-DRB1 alleles on the genetic susceptibility to MS and to study their impact on disability progression in a Spanish population.

METHODS

HLA-DRB1 typing was performed by PCR-SSP in 380 patients with sporadic MS and 1088 unrelated healthy controls. Allelic frequencies were compared between groups. We studied the correlation between the different alleles and the progression of MS.

RESULTS

The HLA-DRB1*15 allele in patients with MS had a statistically significant higher frequency when compared with controls (18.9% in patients vs. 10.1% in controls, Odds ratio (OR)=2.07, 95% CI=1.64-2.60, P<0.001). In the univariate analysis, the DRB1*01 and DRB1*04 alleles were associated with a worse prognosis when considering the time to reach an EDSS of 6, whereas the DRB1*03 was correlated with a better outcome. In the multivariate analysis, the alleles*01 and *04 were demonstrated to be independent factors to have a worse prognosis.

CONCLUSIONS

HLA-DRB1*15 is associated with MS when comparing patients with unrelated healthy controls in a Spanish population. The HLA-DRB1*01 and HLA-DRB1*04 alleles are related to a worse prognosis when considering the time taken to reach severe disability.

Heterogeneity at the HLA-DRB1 allelic variation locus does not influence multiple sclerosis disease severity, brain atrophy or cognition

BACKGROUND

HLA-DRB1*1501 (DR15) and other HLA class II alleles increase the risk of developing multiple sclerosis (MS). However, the contribution of genetic heterogeneity to the clinical course of MS remains controversial. We examined the influence of DR15 and other common DRB1 alleles (DRB1*01 (DR1), DRB1*03 (DR3) and DRB1*04 (DR4) on MS severity in a large, Australian, population-based cohort.

METHODS

We studied the association between common HLA-DRB1 alleles and genotypes and age of onset as well as three clinical disease severity descriptors: Multiple Sclerosis Severity Score, progression index), and the interval between the first and second attack in 978 patients with relapsing remitting MS and secondary progressive MS. We assessed cognition using the Symbol Digit Modalities Test in 811 patients and brain atrophy using the linear magnetic resonance imaging marker, the intercaudate ratio, in 745 patients.

RESULTS

Carrying DR15 significantly decreased the age of MS onset by 3.2 years in homozygotes and 1.3 years in heterozygotes. Carrying the HLA-DR15, -DR1, -DR3 or -DR4 alone or in combination did not affect clinical disease severity, cognition or cerebral atrophy.

CONCLUSIONS

This study confirms that heterogeneity of HLA-DRB1 does not influence disease outcome in relapsing MS patients, with the exception of a younger age of onset in HLA-DR15 carriers.

Multiple sclerosis susceptibility-associated SNPs do not influence disease severity measures in a cohort of Australian MS patients

Recent association studies in multiple sclerosis (MS) have identified and replicated several single nucleotide polymorphism (SNP) susceptibility loci including CLEC16A, IL2RA, IL7R, RPL5, CD58, CD40 and chromosome 12q13-14 in addition to the well established allele HLA-DR15. There is potential that these genetic susceptibility factors could also modulate MS disease severity, as demonstrated previously for the MS risk allele HLA-DR15. We investigated this hypothesis in a cohort of 1006 well characterised MS patients from South-Eastern Australia. We tested the MS-associated SNPs for association with five measures of disease severity incorporating disability, age of onset, cognition and brain atrophy. We observed trends towards association between the RPL5 risk SNP and time between first demyelinating event and relapse, and between the CD40 risk SNP and symbol digit test score. No associations were significant after correction for multiple testing. We found no evidence for the hypothesis that these new MS disease risk-associated SNPs influence disease severity.

The genetics of clinical outcome in multiple sclerosis

Multiple sclerosis (MS) is a common inflammatory disease of the central nervous system (CNS), the clinical course of which varies considerably between patients. Genetic complexity and interactions with as yet unknown environmental factors have hindered researchers from fully elucidating the aetiology of the disease. In addition to influencing disease susceptibility, epidemiological evidence suggests that genetic factors may affect phenotypic expression of the disease. Genes that affect clinical outcome may be more effective therapeutic targets than those which determine susceptibility. We present in this review a comprehensive survey of the genes (both MHC- and non-MHC-related) that have been investigated for their role in disease outcome in MS. Recent studies implicating the role of the genotype and epistatic interactions in the MHC in determining outcome are highlighted.

An extremes of outcome strategy provides evidence that multiple sclerosis severity is determined by alleles at the HLA-DRB1 locus

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-DR15 haplotype and multiple sclerosis: a HuGE review

An association between multiple sclerosis (MS) and the human leukocyte antigen (HLA) complex, a dense cluster of genes on the short arm of chromosome 6, was first noted over 30 years ago. In Caucasian populations of Northern European descent, the DR15 haplotype (DRB1*1501-DQA1*0102-DQB1*0602) has been hypothesized to be the primary HLA genetic susceptibility factor for MS. However, studies of other populations have produced varying results. Thus, the authors reviewed the literature for articles on the association between the DR15 haplotype and MS. They identified 72 papers meeting the inclusion criteria: human genetic studies written in English that were published between 1993 and 2004 and that reported allele frequencies for HLA-DRB1*1501, HLA-DQA1*0102, or HLA-DQB1*0602 or the frequency of the DRB1*1501-DQA1*0102-DQB1*0602 haplotype. Most of the studies identified used a case-control design (n = 60), while the remainder used a family-based design (n = 22). In most of these papers, investigators reported a higher frequency of the DR15 haplotype and/or its component alleles among MS cases than among controls. However, the authors' confidence in these results is tempered by factors related to study design that may have biased the outcomes.

The role of HLA-DRB1 alleles on susceptibility and outcome of a Portuguese Multiple Sclerosis population

BACKGROUND

The association between susceptibility to multiple sclerosis (MS) and HLA-DRB1*15 has been reported in various European populations.

OBJECTIVE

To investigate the relationship between MS, HLA-DRB1*15 and other DRB1 alleles in a Portuguese population and their association with clinical course of MS.

METHODS

The HLA-DRB1 alleles were analyzed by PCR-SSP in 248 MS patients and 282 healthy controls. In order to relate HLA-DRB1 alleles to disease aggressiveness, patients with relapsing remitting MS and secondary progressive MS were subdivided into 3 groups: 'benign' MS patients who maintain an Extended Disability Status Scale (EDSS) score of <or=3 at least 10 years after disease onset; non-benign MS patients with EDSS>3 after the same period and 'aggressive' MS those with EDSS>or=6 within 15 years of disease onset.

RESULTS

As expected, a higher frequency of HLA-DRB1*15 was found in MS patients (29.8% vs 19.9%, odds ratio (OR)=1.72, 95% CI=1.15-2.56, p=0.008). The HLA-DRB1*03 allele was positively associated with MS in the overall patient population (22.6% vs 15.6%, OR=1.58, 95% CI=1.02-2.45). Concerning disease aggressiveness, HLA-DRB1*15 occurred more frequently in the group with benign disease (42.6% vs 19.9%, OR=2.99, 95% CI=1.56-5.72) and in the group with non-benign disease (34.1% vs 19.9%, OR=2.09, 95% CI=1.05-4.16) compared with controls. When time to reach an EDSS=3 or EDSS=6 was considered as end point, HLA-DRB1*15 negative patients were found to have a worse prognosis.

CONCLUSIONS

In this population of Portuguese MS patients, the HLA-DRB1*15 allele is established as a genetic marker for susceptibility to MS and is also associated with a better outcome.

Gender differences in neurological disease: role of estrogens and cytokines

Increasing evidence suggests that inflammatory response may be a critical component of different brain pathologies. However, the role played by this reaction is not fully understood. The present findings suggest that neuroinflammtory mediators such as cytokines may be involved in a number of key steps in the pathological cascade of events leading to neuronal injury. This hypothesis is strongly supported by experimental and clinical observations indicating that inhibition of the inflammatory reaction correlates with less neuronal damage. Estrogens are thought to play a role in the sex difference observed in many neurological diseases with inflammatory components including stroke, Alzheimer's and Parkinson's diseases, multiple sclerosis, or amyotrophic lateral sclerosis. Clinical and experimental studies have established estrogen as a neuroprotective hormone in these diseases. However, the exact mechanisms involved in the neuroprotective effects of estrogens are still unclear. It is possible that the beneficial effects of these hormones may be dependent on their inhibitory activity on the inflammatory reaction associated with the above-mentioned brain pathologies. Here, we review the current clinical and experimental evidence with respect to the inflammation-modulating effects of estrogens as one potential explanatory factor for sexual dimorzphism in the prevalence of numerous neurological diseases.

Multiple sclerosis genetics: leaving no stone unturned

Compelling epidemiologic and molecular data indicate that genes play a primary role in determining who is at risk for developing multiple sclerosis (MS), how the disease progresses, and how someone responds to therapy. The genetic component of MS etiology is believed to result from the action of allelic variants in several genes. Their incomplete penetrance and moderate individual effect probably reflects epistatic interactions, post-transcriptional regulatory mechanisms, and significant environmental influences. Equally significant, it is also likely that locus heterogeneity exists, whereby specific genes influence susceptibility and pathogenesis in some individuals but not in others. With the aid of novel analytical algorithms, the combined study of genomic, transcriptional, proteomic, and phenotypic information in well-controlled study groups will define a useful conceptual model of pathogenesis and a framework for understanding the mechanisms of action of existing therapies for this disorder, as well as the rationale for novel curative strategies.

Complex interactions among MHC haplotypes in multiple sclerosis: susceptibility and resistance

Mechanisms for observed associations within the major histocompatibility complex (MHC) and autoimmune diseases including multiple sclerosis (MS) remain uncertain. Genotyping of the HLA Class II DRB1 locus in 4347 individuals from 873 multiplex families with MS highlights the genetic complexity of this locus. Excess allele sharing in sibling pair families lacking DRB1*15 and DRB1*17 (58.5% sharing; P=0.012) was comparable to that seen where parents were DRB1*15 positive (62%, P=0.0006). DRB1*17 (P=0.00027) was clearly established as an MS susceptibility allele in addition to DRB1*15 (P<10(-14)). DRB1*14 showed striking under-transmission (P=0.000032) to affected offspring newly establishing this allele as a broadly acting resistance factor. Trans interactions were seen in both DRB1*15 and non-DRB1*15 bearing genotype combinations. DRB1*08 was transmitted preferentially with DRB1*15 (P=0.0114) and, in the presence of DRB1*08, the transmission of DRB1*15 was almost invariable (37 transmissions to one non-transmission). DRB1*01 was under-transmitted to offspring in the presence of DRB1*15 (P=0.019). Both DRB1*01 and DRB1*14 haplotypes carry DQA1*01-DQB1*05 alleles, suggesting a common DQ-related mechanism for the protection mediated by these haplotypes. These studies demonstrate that it is the Class II genotype that determines susceptibility and resistance to MS. By analogy with celiac disease and type I diabetes, the pattern of susceptibility strongly supports an autoimmune aetiology.

Genetics of multiple sclerosis

Multiple sclerosis (MS) is probably aetiologically heterogeneous. Systematic genetic epidemiological and molecular genetic studies have provided important insights. Both genetic and non-genetic (environment, stochastic) factors may be involved in susceptibility as well as outcome, but we have yet to understand their relative roles. Any environmental factor is likely to be ubiquitous and act on a population-basis rather than within the family microenvironment. Taken together, the results of genome screening studies provide strong evidence for exclusion of a major locus in MS. There are, however, many genes that seem to be associated with MS. These include, but are in no way limited to, HLA classes I and II, T-cell receptor beta, CTLA4, ICAM1, and SH2D2A. The future of MS genetics, as for most common complex disorders, will be dependent on the resources available, ranging from biological samples and comprehensive databases of clinical and epidemiological information to the development of new technologies and statistical methods.

Long-term follow up of patients with clinically isolated syndromes, relapsing-remitting and secondary progressive multiple sclerosis

This paper extends on previous data on prognosis in multiple sclerosis (MS), to encompass the entire course of the disease. The first episode suggestive of MS [the clinically isolated syndrome (CIS)] was included as a starting point, and the speed of secondary progression as an end point. Primary progressive MS was not included. Unique preconditions, with one neurological service covering the Göteborg district, allowed for establishing a strictly population-based, essentially untreated 15-year incidence cohort of 308 MS patients who were followed for 25 years. Survival analysis was performed as Kaplan-Meyer graphs, and independent predictors were ascertained by Cox regression analysis. A matrix of several predictors and end points was created. From CIS, a higher risk of developing clinically definite MS (CDMS), secondary progressive course and Disability Status Scale 7 (DSS7) was predicted by efferent tract lesions. However, less than 25% had reached DSS7 25 years after CIS with pure afferent lesions or other favorable predictors. During the first five years, higher relapse frequency, as well as incomplete remission of early bouts, predicted higher risks of secondary progressive course and DSS7 during follow-up to 25 years. However, these early predictors were unable to predict the rate of progression, which seems to contain an element of the disease process unassociated with its early events. Only late predictors, such as a shorter time from onset to secondary progression (1-10 years) and a higher number of functional systems involved at onset of progression predicted a faster progression rate. Predictors from this study could be used to refine historically controlled trials.

Genetics of multiple sclerosis: linkage and association studies

Multiple sclerosis (MS) is a demyelinating autoimmune disease of the central nervous system caused by an interplay of environmental and genetic factors. The only genetic region that has been clearly demonstrated by linkage and association studies to contribute to MS genetic susceptibility is the human leukocyte antigen (HLA) system. The majority of HLA population studies in MS have focused on Caucasians of Northern European descent, where the predisposition to disease has been consistently associated with the class II DRB1*1501-DQA1*0102-DQB1*0602 haplotype. A positive association with DR4 was detected in Sardinians and in other Mediterranean populations. Moreover DR1, DR7, DR11 have been found to be protective in several populations. Systematic searches aimed at identifying non-HLA susceptibility genes were undertaken in several populations by means of linkage studies with microsatellite markers distributed across the whole genome. The conclusion of these studies was that there is no major MS locus, and genetic susceptibility to the disease is most likely explained by the presence of different genes each conferring a small contribution to the overall familial aggregation. The involvement of several candidate genes was tested by association studies, utilizing either a population-based (case control) or a family-based (transmission disequilibrium test) approach. Candidate genes were selected mainly on the basis of their involvement in the autoimmune pathogenesis and include immunorelevant molecules such as cytokines, cytokine receptors, immunoglobulin, T cell receptor subunits and myelin antigens. With the notable exception of HLA, association studies met only modest success. This failure may result from the small size of the tested samples and the small number of markers considered for each gene. New tools for large scale screening are needed to identify genetic determinants with a low phenotypic effect. Large collaborative studies are planned to screen several thousands of patients with MS with several thousands of genetic markers. The tests are increasingly based on the DNA pooling procedure.

Estrogen receptor gene polymorphism and multiple sclerosis in Japanese patients: interaction with HLA-DRB1*1501 and disease modulation

We investigated PvuII and XbaI polymorphism in the estrogen receptor gene (ERG) and HLA-DRB1*1501 positivity in 116 conventional multiple sclerosis (MS) patients and 101 healthy controls in a Japanese population. Logistic analysis revealed independent associations of [P] allele in the profiles for PvuII (p=0.0005, adjusted odds ratio (aOR)=3.17) and DRB1*1501 (p=0.0089, aOR=2.61) with conventional MS. Synergistic elevated risk of MS due to interaction between the [P] allele and HLA-DRB1*1501 allele was found among female patients (odds ratio=16.0; 95% CI=3.99-63.8, p<0.0001). The [P] allele-positive patients with disease duration of more than 5 years had a significantly higher progression index (PI) of disability (p=0.0230) and a worse ranked MS severity score (p=0.0152) than their non-[P] counterparts.

Identifying disease modifying genes in multiple sclerosis

Evidence is mounting that genetic variation influences not only susceptibility to multiple sclerosis (MS), but also its course and severity. Identification of disease modifying genes, however, poses unique challenges, especially on how to classify the course and outcome of the disease in ways that may be relevant to analysis of biological factors that might be influenced by genes. The power of the statistical approaches to detect small effects of individual genes in complex disorders such as MS is problematic, and approaches to estimate power must be appropriate for the data. Nonetheless, using contemporary schemes of classification, genetic variants that influence disease course have been found; in fact, a small number have been confirmed to influence disease course in two or more independent studies. This review addresses strategies relevant to identification of disease modifying genes in MS, and summarizes and critically evaluates the current state of knowledge in this area.

HLA-DR 15 is associated with female sex and younger age at diagnosis in multiple sclerosis

BACKGROUND

The association between multiple sclerosis and class II alleles of the major histocompatibility complex, in particular the DRB1*1501-DQB1*0602 haplotype, is well established but their role in determining specific features of this clinically heterogeneous disease is unknown as few studies involving large sample sizes have been performed.

METHODS

729 patients with multiple sclerosis were typed for the HLA DR15 phenotype. All patients underwent clinical assessment and a detailed evaluation of their clinical records was undertaken.

RESULTS

The presence of DR15 was associated with younger age at diagnosis and female sex but there was no association with disease course (relapsing-remitting or secondary progressive v primary progressive type), disease outcome, specific clinical features (opticospinal v disseminated form), diagnostic certainty (clinically and laboratory supported definite v clinically probable multiple sclerosis), and paraclinical investigations including the presence of oligoclonal bands in the CSF or characteristic abnormalities on MRI imaging of the central nervous system.

CONCLUSION

Even though DR15 carriers are more likely to be female and prone to an earlier disease onset, the results indicate that there is no association with other specific clinical outcomes or laboratory indices examined here. This suggests that DR15 exerts a susceptibility rather than disease modifying effect in multiple sclerosis.

Genetic basis for clinical expression in multiple sclerosis

Multiple sclerosis is a clinically heterogeneous demyelinating disease and an important cause of acquired neurological disability. An underlying complex genetic susceptibility plays an important role in multiple sclerosis aetiology; however, the role of genetic factors in determining clinical features of multiple sclerosis is unknown. We studied 184 stringently ascertained Caucasian multiple sclerosis families with multiple affected cases. A detailed evaluation of patient histories identified clinical variables including age of onset, initial clinical manifestations and disease severity. The concordance within families for continuous and categorical clinical variables was investigated using an intraclass correlation or Cohen's kappa coefficient, respectively. Genetic analyses included model-dependent, model-independent and association methodology. Linear and logistic regression models were used to evaluate the effect of human leucocyte antigen (HLA)-DR2 (DRB1*1501, DQB1*0602) on clinical outcome, taking account of correlation within families. Significant concordance for early clinical manifestations within families was observed for individuals with exclusive optic neuritis and/or spinal cord involvement as first and second multiple sclerosis attacks (P < 10(-6)). Linkage (LOD = 3.80, theta = 0.20) and association (P = 0.0002) to HLA-DR were present in the dataset; however, linkage was restricted to families in which the DR2 haplotype was present in at least one nuclear member. No evidence for linkage to HLA-DR in DR2-negative families was observed. When families were stratified by concordance of early clinical manifestations, a significant DR2 association was present in all subgroups. Concordance for early manifestations of multiple sclerosis was present in this familial dataset, but was not associated with HLA-DR2. The association of DR2 in families with different clinical presentations suggests that a common basis exists for susceptibility in multiple sclerosis. However, non-HLA genes or other epigenetic factors must modulate disease expression. Locus heterogeneity at the HLA region suggests a distinct immunopathogenesis in DR2 negative patients.

HLA class II associated risk and protection against multiple sclerosis-a Finnish family study

We analyzed the HLA class II haplotypes in 249 Finnish nuclear families and compared the frequencies of parental haplotypes transmitted or non-transmitted to multiple sclerosis (MS) patients. The most important predisposing haplotype was DRB1*15-DQB1*0602 (P<10(-6)) as expected and a weak predisposing effect of DRB1*04-DQB1*0302 was revealed after the elimination of DRB1*15-DQB1*0602. HLA-DRB1*01-DQB1*0501 and DRB1*13-DQB1*0603 were negatively associated with MS in transmission disequilibrium test, but only the DRB1*13-DQB1*0603 association remained significant (P=0.008) after the elimination of DRB1*15-DQB1*0602 haplotypes. Based on this study HLA class II haplotypes exhibit both predisposing and protective effects in MS.

Multiple sclerosis: genomic rewards

A large body of immunologic, epidemiologic, and genetic data indicate that tissue injury in multiple sclerosis (MS) results from an abnormal immune response to one or more myelin antigens that develops in genetically susceptible individuals after exposure to an as-yet undefined causal agent. The genetic component of MS etiology is believed to result from the action of several genes of moderate effect. The incomplete penetrance of MS susceptibility alleles probably reflects interactions with other genes, post transcriptional regulatory mechanisms, and significant nutritional and environmental influences. Equally significant, it is also likely that genetic heterogeneity exists, meaning that specific genes influence susceptibility and pathogenesis in some affects but not in others. Results in multiplex MS families confirm the genetic importance of the MHC region in conferring susceptibility of MS. Susceptibility may be mediated by the class II genes themselves (DR, DQ or both), related to the known function of these molecules in the normal immune response, e.g. antigen binding and presentation and T cell repertoire determination. The possibility that other genes in the MHC or the telomeric region of the MHC are responsible for the observed genetic effect cannot be excluded. The data also indicate that although the MHC region plays a significant role in MS susceptibility, much of the genetic effect in MS remains to be explained. Some loci may be involved in the initial pathogenic events, while others could influence the development and progression of the disease. The past few years have seen real progress in the development of laboratory and analytical approaches to study non-Mendelian complex genetic disorders and in defining the pathological basis of demyelination, setting the stage for the final characterization of the genes involved in MS susceptibility and pathogenesis. Their identification and characterization is likely to define the basic etiology of the disease, improve risk assessment and influence therapeutics.

Sex and age at diagnosis are correlated with the HLA-DR2, DQ6 haplotype in multiple sclerosis

The HLA-DR2, DQ6 (i.e., HLA-DRB1*1501, DQA1*0102, DQB1*0602) haplotype contributes to the risk of developing multiple sclerosis (MS) in Caucasoids of Northern European heritage. A correlation between the clinical expression of MS and the presence of HLA-DR2, DQ6 has, however, not convincingly been shown. In this study conventional bivariate analysis and logistic regression analysis were used to study the relationship between HLA-DR2, DQ6 and four disease variables in a cohort of 286 Norwegian MS patients from the Oslo area. Logistic regression analysis showed that HLA-DR2, DQ6 was significantly more frequent among female than male patients (P=0. 0251), and was negatively correlated with age at diagnosis regardless of sex (P=0.0254). No significant correlation was observed between HLA-DR2, DQ6 and type of disease (relapsing-remitting versus primary chronic progressive MS) or presence/absence of oligoclonal bands in the cerebrospinal fluid.

HLA DRB1*1501 and intrathecal inflammation in multiple sclerosis

CD4 T cells are considered to be pivotal in the pathogenesis of multiple sclerosis (MS), and the human leukocyte antigen (HLA) haplotype associated with DRB1*1501 confers susceptibility to MS in patients of Northern European descent. Some previous studies have suggested an association of DRB1*1501 with T- and B-cell reactivity to specific myelin protein peptides, other studies suggested an association with enhanced cytokine production or intrathecal immunoglobulin (Ig) synthesis. In order to further assess the role of DRB1*1501 in the pathogenesis of MS, we studied intrathecal inflammation and T-cell phenotypes in patients with possible onset symptoms or clinically definite MS. Presence of DRB1*1501 was associated with higher levels of cerebrospinal fluid (CSF) inflammation as assessed by IgG synthesis levels and higher levels of matrix metalloproteinase-9 activity. DRB1*1501-positive patients also had a lower percentage of T cells in CSF expressing HLA-DR without co-expressing CD25. These findings suggest that enhanced intrathecal inflammation and an altered T-cell activation status may be of importance in conferring the DRB1*1501-associated susceptibility to MS.

CTLA-4 gene polymorphism may modulate disease in Japanese multiple sclerosis patients

Multiple sclerosis (MS) is widely believed to have a T-cell-mediated autoimmune etiology. The CTLA-4 gene is a strong candidate for involvement in autoimmune diseases because it plays an important role in the termination of T-cell activation. To examine the genetic association of the CTLA-4 gene locus with MS, we analyzed the CTLA-4 gene exon 1 A/G polymorphism in 74 Japanese MS patients and 93 controls. We also investigated the possible interactions of the CTLA-4 gene polymorphism with clinical course and severity, with MRI findings, with another genetic marker-HLA antigens, and with oligoclonal bands (OCB) in the cerebrospinal fluid (CSF). The CTLA-4 exon 1 polymorphism was similar between MS patients and controls. Conversely, clinical disability was significantly more severe in AA homozygous patients than in the other patients, and the allele frequency and the phenotype frequency of the A allele were significantly higher in patients with severe-grade MRI findings of cerebral white matter than in patients with mild-grade MRI findings. The allele frequency and the phenotype frequency of the A allele were significantly higher in patients with OCB than in patients without. This CTLA-4 polymorphism may modulate the prognosis of patients with MS and may be relevant to generation of OCB in the CSF.

Familial factors influence disability in MS multiplex families. French Multiple Sclerosis Genetics Group

BACKGROUND

Both genetic and environmental factors play a role in the pathophysiology of MS and may influence the clinical expression of the disease.

OBJECTIVE

To determine the contribution of familial factors to the clinical expression of MS.

METHODS

The French Multiple Sclerosis Genetics Group identified 87 sibling pairs. For each patient, sex, age at onset, duration of the disease, and disease course from onset were recorded. Disability was determined by the progression index (PI), defined as the ratio of the Expanded Disability Status Scale (EDSS) score disease duration when the latter exceeded 5 years. Statistical analyses were performed either with a group of patients (clinical features, relation between human leukocyte antigen and clinical features) or with a group of sibpairs (concordance for clinical features).

RESULTS

The mean age at onset was 29.6 years, the ratio of women to men was 59:28, and the mean PI was 0.27. There was no correlation for disease course and age at onset between sibs with MS. In contrast, we observed a weak but significant correlation of the PI in MS sibpairs (r = 0.234, p = 0.03).

CONCLUSION

This study revealed a concordance in MS sibling pairs for the disease severity, supporting the hypothesis that the degree of disability might be partly influenced by familial factors (environmental or genetic).

A study of the HLA-DR region in clinical subgroups of multiple sclerosis and its influence on prognosis

OBJECTIVE

To investigate the HLA-DR associations in relapsing-remitting/secondary progressive multiple sclerosis (RR/SPMS) and primary progressive MS (PPMS). The HLA-DR2 allele (or its split, HLA-DRB1*15) is felt to be a risk factor for MS, rather than a genetic marker for the population of origin. Some studies have indicated a different HLA-DR antigen profile in PPMS patients compared with those having an initially relapsing-remitting course, only those with relapsing disease showing an increase in HLA-DR2. Association of PPMS with DR4 has been suggested. Several DR alleles have also been felt to influence the prognosis in MS.

METHODS

Genomic DNA was prepared from peripheral blood of 202 RR/SPMS patients identified in a population-based prevalence study, 102 PPMS patients identified throughout Northern Ireland and 398 normal controls (Nor) matched for the postcode areas of those identified in the prevalence study. Samples were typed for the HLA-DR antigens using polymerase chain reaction (PCR) technology and sequence specific oligonucleotide probes (SSOP).

RESULTS

A high incidence of HLA-DRB1*15 was found in each MS group - PPMS (63.73%), RR/SPMS (66.83%) - compared with normals (32.41%), (PPMS vs. Nor, P<0.0001: RR/SPMS vs. Nor, P<0.0001). HLA-DRB1*04 occurred at a lower incidence in both MS groups compared with controls - RR/SPMS (22%), PPMS (30%), Nor (35%). Overall, highly significant differences existed across the full HLA-DR allele distribution (RR/SPMS vs. Nor, P<0.0001, df=12: PPMS vs. Nor, P=0.0007, df=12). No significant differences existed between PPMS and RR/SPMS (P=0.47, df=12), and the allele distributions in benign and aggressive MS were similar.

CONCLUSIONS

These data suggest that in this population, HLA-DRB1*15 is indeed associated with PPMS and that PPMS has a HLA-DR profile distinct from the normal population but not from those with an initially relapsing-remitting course. No single allele is associated with either a good or poor prognosis.

Expression of the human histocompatibility leukocyte antigen DR3 transgene reduces the severity of demyelination in a murine model of multiple sclerosis

The role of various MHC genes in determining the progression of multiple sclerosis (MS) remains controversial. The HLA-DR3 gene has been associated with benign relapsing MS in some genetic epidemiologic studies, but with disease progression in others. We induced demyelination in highly susceptible B10.M and B10.Q mice expressing the DR3 (HLA-DRB1*0301) transgene to determine directly the effects of a human transgene by infecting them with Theiler's murine encephalomyelitis virus (TMEV). DR3+ mice experienced a dramatic reduction in the extent and severity of demyelination compared with DR3- littermate controls, whereas anti-TMEV antibody titers, delayed-type hypersensitivity responses, and levels of infectious virus, virus antigen, and virus RNA were similar in both groups. To address a possible mechanism of how the human transgene is reducing virus-induced demyelination, we analyzed cytokine expression in the lesions and also determined whether B10.M mice can respond to peptides derived from the DR3 molecule. Intense staining for IFN-gamma and IL-4, T helper (TH) 1 and TH2 cytokines, respectively, was found in the lesions of TMEV-infected DR3- mice but not in the DR3+ transgenic mice at day 21 after infection. DR3 peptides elicited strong proliferative responses in B10.M mice but not in B10.M (DR3+) mice. These experiments are the first to demonstrate that a human class II DR gene can alter the severity of demyelination in an animal model of MS without influencing viral load. These experiments are consistent with a mechanism by which DR3 reduces demyelination by altering the cytokine expression in the lesions, possibly by deleting T cells involved in virus-induced pathology.

Distribution of HLA-Dw2 in optic neuritis and multiple sclerosis indicates heterogeneity

The human leukocyte antigen (HLA) phenotype Dw2 is known to be increased in multiple sclerosis (MS), but only slightly in optic neuritis (ON).

MATERIAL AND METHODS

127 consecutive patients with unilateral monosymptomatic ON were typed genomically for HLA-DR and -DQ genes.

RESULTS

The frequency of HLA-Dw2 among ON patients (47%) was found to be significantly higher than among 250 controls (30%) but significantly lower than in a group of 245 MS patients (60%), all of the same ethnic origin. At the group level, these figures can be calculated to indicate that 53% of the ON patients belong to the group of "MS-type ON" (95% confidence limits 25-78%). A compilation of published data on the frequency of the HLA-DR17(3), DQ2 haplotype, prompted by a slight increase in this material, revealed a significant association with this haplotype in ON, after compensation for the increase of Dw2.

CONCLUSION

ON differs from both MS and controls regarding HLA-Dw2. Thus, a substantial number of patients with ON may suffer from conditions not immuno-genetically related to MS, which might be designated as non-MS type ON. This condition may be more common in men and in young patients of both sexes.

Urinary myelin basic protein-like material as a correlate of the progression of multiple sclerosis

In the multicenter, randomized, placebo-controlled trial of alternate-day injections of recombinant interferon beta-1b in relapsing-remitting multiple sclerosis (MS), urine specimens were collected periodically from all patients (n = 64) in two of the clinical test sites over the 2 years of the study. Urine specimens were also collected over two consecutive 24-hour periods from 43 patients from a third center. Urine samples were assayed for their content of myelin basic protein-like material (MBPLM), the level of which was correlated with clinical changes, cranial magnetic resonance imaging results, and the development of progressive disease. Concordant changes in creatinine values affected some of the relationships of MBPLM. The level of urinary MBPLM correlated with a chronic progressive course and with the number of lesions and the total lesion area on cranial magnetic resonance images. A rise in the level of urinary MBPLM appeared to antedate the clinical transition from a relapsing-remitting to a chronic progressive course. By chance, the randomized entry of patients led to significant differences in urinary MBPLM levels among the three treatment groups, thus precluding correlation studies of treatment effects. However, the patient group from which 24-hour specimens were collected showed that the patients with relapsing-remitting MS changing to a chronic progressive course, and more specifically, those patients with chronic progressive MS receiving placebo, had the highest values of urinary MBPLM. These findings indicate that urinary MBPLM may offer an objective test and possibly serve as a surrogate marker for detecting or predicting the failure of remission or the transition to a progressive phase of MS.