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

Familial vs sporadic multiple sclerosis in the Israeli population: Differences in ethnicity distribution and disease progression, with anticipation in successive generations

BACKGROUND

Multiple Sclerosis (MS) may cluster in families, an entity known as familial MS (FMS), possibly due to aggregation of genetic and environmental factors. Though previous studies have characterized FMS in different populations, no study to the best of our knowledge has yet characterized FMS in the unique Israeli population, which is comprised of relatively endogamous ethnicities. Our goal in this study was to compare demographic and clinical characteristics between FMS and sporadic MS (SMS), and to search for intra-familial patterns.

METHODS

In a retrospective study of 101 FMS patients and 508 SMS patients, ethnicity and sex distribution was assessed. Clinical aspects were compared between 172 paired FMS and SMS patients, matched for sex, age and ethnicity, and between generations of the FMS cohort.

RESULTS

Females comprised 75.3 % of FMS and 67.5 % of SMS patients (p = 0.1). Ethnic distribution was significantly different between FMS and SMS (p = 0.014), with the former comprising a higher proportion of Christian-Arabs (15.4% vs. 5.1 %, p = 0.004) and lower proportion of Jews (60% vs. 74.2 %, p = 0.016). Age at disease onset or diagnosis, frequency of positive Oligoclonal bands and comorbidity of other autoimmune/inflammatory disease or chronic diseases was comparable between FMS and SMS, yet motor symptoms at onset were more prevalent in FMS (34% vs. 20 %, p = 0.02). Annualized relapse rates throughout 10 years from onset were comparable. Among FMS, mean Expanded-Disability-Status-Scale (EDSS) and slope of deterioration in EDSS over 20 years from diagnosis were higher (p = 0.0004 and p = 0.023, respectively), time to EDSS ≥ 3 was shorter (7.1 vs. 12.1 years, HR 1.6, p = 0.036) and MS-Severity-Score (MSSS) was higher (3.84 vs. 2.95, p = 0.04), compared to SMS. Following adjustment for smoking, which tended to be higher among FMS patients (P = 0.06), mean EDSS and slope of deterioration in EDSS over 20 years remained significantly higher (p = 0.0006 and p = 0.025, respectively) in FMS, time to EDSS ≥ 3 tended to be higher (HR 1.5, p = 0.06), while MSSS was comparable. An inter-generational analysis of the total FMS cohort, as well as an intra-familial analysis, both adjusted for year of diagnosis, revealed significantly earlier age of onset (p < 0.0001 and p < 0.0001) and diagnosis (p = 0.001 and p < 0.0001) in the younger compared to the older generations, respectively.

CONCLUSION

In this Israeli cohort, the proportions of specific ethnicities differ between FMS and SMS, indicating that FMS has a population-specific prevalence pattern, and that further investigation for susceptibility genes is warranted. Disease progression is faster in FMS patients and anticipation is observed in families with multiple cases of MS. Closer surveillance and application of a pro-active induction or early highly-effective therapeutic strategy for FMS patients should be considered, to reduce high disease activity and fast disability progression.

Distribution of disease courses in familial vs sporadic multiple sclerosis

OBJECTIVES

The overall distribution of disease courses in multiple sclerosis (MS) is well established, but little is known about the distribution among familial MS cases. We examine the frequency of the different MS courses among familial and sporadic MS cases and determine whether MS cases within the same family had the same age at diagnosis and have experienced the same disease course.

MATERIALS AND METHODS

This is a nationwide register study, based on data from the Danish MS Registry, the Danish Civil Registration System, and the Danish National Patient Registry. The main variables are MS diagnosis, MS course, and first-degree relatives with MS The statistical analyses were carried out using logistic regression analysis, Kappa coefficient, and intraclass correlations coefficient.

RESULTS

In total, 7402 MS cases were included in the study, of which 531 have an affected first-degree relatives, and 6871 are sporadic. We found that relapsing-remitting MS including secondary progressive MS was more common among familial MS cases than among sporadic MS cases (Odds ratio = 1.64, 95% CI: 1.20-2.24, P = 0.002). We subsequently analyzed data on 133 MS families and found that MS courses correlate between the first and the second MS case diagnosed, while age at diagnosis does not.

CONCLUSION

Familial MS cases are more likely to have relapsing-remitting MS than a progressive course compared to sporadic MS cases. Secondly, we find that within MS families, first-degree relatives are likely to have the same MS course, but we do not find that they are diagnosed at the same age.

A genetic basis for multiple sclerosis severity: Red herring or real?

Multiple Sclerosis (MS) is an autoimmune degenerative disease of the central nervous system, characterized by multifocal demyelination and neurodegeneration. The genetic architecture of MS is complex, where genetic risk has been attributed to over 100 polymorphic loci each with small odds ratios. MS is a highly heterogeneous disease with numerous clinical and paraclinical endophenotypes. To-date, no genetic variant has been associated with clinical outcome, however, evidence exists that MS outcomes, like risk, are to an extent also controlled by genetic variation. Here we summarise the current evidence for genetic determination of disease outcomes and make recommendations for future research directions.

Familial forms of multiple sclerosis and neuromyelitis optica at an MS center in Rio de Janeiro State, Brazil

OBJECTIVE

To describe familial forms of demyelinating diseases from an MS referral center in Río de Janeiro State, Brazil.

METHODS

A descriptive, cross-sectional study was done to identify familial IIDD cases in Hospital da Lagoa, a public hospital where 75% of patients with IIDD who live in Rio de Janeiro state, located in the Southeast region of Brazil, are referred. The diagnoses of all consecutive patients followed in 2011 were reviewed to apply new diagnostic criteria (Wingerchuk et al., 2008). The diagnosis of IIDD was confirmed based on clinical history, neurological examination, MRI of the skull and spinal cord, CSF analysis and investigation of IgG NMO antibodies. The cases that had at least one other relative with IIDD were selected for the study.

RESULTS

Familial forms were found only in the multiple sclerosis (MS) and neuromyelitis optica syndrome (NMOSD) categories. 23 MS families were identified, 60.86% with first degree kinship. It has a Caucasian preponderance, 90% of whom were white. The frequency of early onset was 15% and 20% of the MSf cases have progressive primary course.

CONCLUSION

The frequency of familial cases of IIDD was 6.12% among MS patients and 2.8% in NMO spectrum syndromes.

Genetic determinants of risk and progression in multiple sclerosis

Multiple sclerosis (MS) is an autoimmune disease that represents a primary cause of neurological disability in the young adult population. Converging evidence supports the importance of genetic determinants for MS etiology. However, with the exception of the major histocompatibility complex, their nature has been elusive for more than 20 years. In the last decade, the advent of large genome-wide association studies has significantly improved our understanding of the disease, leading to the golden era of MS genetic research. To date more than 110 genetic variants have been firmly associated to an increased risk of developing MS. A large part of these variants tag genes involved in the regulation of immune response and several of them are shared with other autoimmune diseases, suggesting a common etiological root for this class of disorders. Despite the impressive body of data obtained in the last years, we are still far from fully decoding MS genetic complexity. For example, we ignore how these genetic factors interact with each other and with the environment. Thus, the biggest challenge for the next era of MS research will consist in identifying and characterizing the molecular mechanisms and the cellular pathways in which these risk variants play a role.

Analysis of genes, pathways and networks involved in disease severity and age at onset in primary-progressive multiple sclerosis

Background:

The role of genetic factors in influencing the clinical expression of multiple sclerosis (MS) is unclear.

Objective:

The objective of this paper is to identify genes, pathways and networks implicated in age at onset (AAO) and severity, measured using the Multiple Sclerosis Severity Score (MSSS), of primary-progressive MS (PPMS).

Methods:

We conducted a genome-wide association study (GWAS) of 470 PPMS patients of Italian origin:. Allelic association of 296,589 SNPs with AAO and MSSS was calculated. Pathway and network analyses were also conducted using different tools.

Results:

No single association signal exceeded genome-wide significance in AAO and MSSS analyses. Nominally associated genes to AAO and MSSS were enriched in both traits for 10 pathways, including: “oxidative phosphorylation” (FDRAAO=9*10−4; FDRMSSS=3.0*10−2), “citrate (TCA) cycle” (FDRAAO=1.6*10−2; FDRMSSS=3.2*10−3), and “B cell receptor signaling” (FDRAAO=3.1*10−2; FDRMSSS=2.2*10−3). In addition, an enrichment of “chemokine signaling pathway” (FDR=9*10−4) for AAO and of “leukocyte transendothelial migration” (FDR=2.4*10−3) for MSSS trait was observed, among others. Network analysis revealed that p53 and CREB1 were central hubs for AAO and MSSS traits, respectively.

Conclusions:

Despite the fact that no major effect signals emerged in the present GWAS, our data suggest that genetic variants acting in the context of oxidative stress and immune dysfunction could modulate the onset and severity of PPMS.

Immunopathogenesis and immunotherapeutic approaches in multiple sclerosis

Multiple sclerosis is an organ-specific autoimmune disease, characterized pathologically by cell-mediated inflammation, demyelination and variable degrees of axonal loss. Although inflammation is considered central to the pathogenesis of multiple sclerosis, to date, the only licensed and hence widely used multiple sclerosis immunotherapies are interferon-beta, glatiramer acetate and mitoxantrone. This review discusses the immunopathogenesis of multiple sclerosis, focusing on a number of emerging immunotherapies. A number of new approaches likely to manipulate the immunopathogenesis of multiple sclerosis and which may ultimately allow for the development of more effective immunotherapy are also highlighted.

Genetics of primary progressive multiple sclerosis

Multiple sclerosis (MS) patients are classified as either having relapsing onset or progressive onset disease, also known as primary progressive MS (PPMS). Relative to relapsing onset patients, PPMS patients are older at disease onset, are equally likely to be men or women, and have more rapid accumulation of disability that does not respond well to treatments used in relapsing onset MS. Although estimates vary, 5-15% of all MS patients have a PPMS disease course. Genetic variance is a proposed determinant of MS disease course. If distinct genes associated with PPMS were identified study of these genes might lead to an understanding of the biology underlying disease progression and neural degeneration that are the hallmarks of PPMS. These genes and their biological pathways might also represent therapeutic targets. This chapter systematically reviews the PPMS genetic literature. Despite the intuitively appealing notion that differences between PPMS and relapsing onset MS are due to genetics, definite differences associated with these phenotypes at the major histocompatibility complex or elsewhere in the genome have not been found. Recent large-scale genome wide screens identified multiple genes associated with MS susceptibility outside the MHC. The genetic variants identified thus far make only weak individual contributions to MS susceptibility. If the genetic effects that contribute to the differences between PPMS and relapsing MS are similar in magnitude to those that distinguish MS from healthy controls then, given the relative scarcity of the PPMS phenotype, very large datasets will be needed to identify PPMS associated genes. International collaborative efforts could provide the means to identify such genes. Alternately, it is possible that factors other than genetics underlie the differences between these clinical phenotypes.

Genome-wide association study of severity in multiple sclerosis

Multiple sclerosis (MS) is a chronic inflammatory disorder of the central nervous system with a strong genetic component. Several lines of evidence support a strong role for genetic factors influencing both disease susceptibility and clinical outcome in MS. Identification of genetic variants that distinguish particular disease subgroups and/or predict a severe clinical outcome is critical to further our understanding of disease mechanisms and guide development of effective therapeutic approaches. We studied 1470 MS cases and performed a genome-wide association study of more than 2.5 million single-nucleotide polymorphisms to identify loci influencing disease severity, measured using the MS severity score (MSSS), a measure of clinical disability. Of note, no single result achieved genome-wide significance. Furthermore, variants within previously confirmed MS susceptibility loci do not appear to influence severity. Although bioinformatic analyses highlight certain pathways that are over-represented in our results, we conclude that the genetic architecture of disease severity is likely polygenic and comprised of modest effects, similar to what has been described for MS susceptibility, to date. However, a role for major effects of rare variants cannot be excluded. Importantly, our results also show the MSSS, when considered as a binary or continuous phenotype variable is by comparison a stable outcome.

Entering a new phase of multiple sclerosis genetic epidemiology

Multiple sclerosis (MS) is a complex disease, where multiple genetic variants have been found to influence the risk of development. The evidence for environmental-attributable risk is also strong, indicating an interaction of risk factors leading to the development of disease in the individual. An importance of genetic variation within the human leukocyte antigen (HLA) region has been known for almost 40 years, but the search for additional variants connected to susceptibility has been long and largely fruitless. Joint efforts of the MS research community in collecting and sharing results from genetic case control cohorts, together with the technical development, eventually lead to the identification of multiple risk factors for MS as in other complex diseases. The list of identified genetic variants associated with disease is increasingly growing and some leads for functional mechanisms are emerging. Many of the identified regions also harbor associations with other immune-mediated diseases, suggesting common etiology across these various diseases. The great challenge in front of us now is to translate these point-wise indications of genetic effects to functional understanding of how disease develops.

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.

Sibling disability risk at onset and during disease progression in familial multiple sclerosis

BACKGROUND

The objective of this study was to address the differences in onset and disease progression between familial and sporadic multiple sclerosis (MS) and the association within sibling pairs.

METHODS

Ninety-eight siblings and their controls were included from a database of 763 sporadic MS-patients, randomly pair-matched for age, gender, clinical course, disease duration and treatment. Sixty-eight available siblings completed a prospective six-year follow-up. Outcome parameters included baseline Expanded Disability Status Scale (EDSS), age at onset, mono- or multifocal onset, disease progression and conversion to secondary progression of initially relapsing-remitting MS. For statistical analyses Wilcoxon's signed-rank statistics for categorical differences, t-statistics for continuous variables, McNemar's test for relative frequencies of categories, intra-class correlations for within sibling-pair associations, or Kaplan-Meier analysis for survival analyses were used; all two-sided at the 5% level.

RESULTS

Disease onset was slightly earlier (29.01 vs. 29.44 years, p = 0.0492) and multifocal onset significantly more often (p = 0.0052) in familial than in sporadic MS. Notably, a substantial within sibling-pair correlation for disease progression (rho = 0.40; p = 0.0062) as well as a higher risk for siblings than for controls to convert into secondary progression (0.545 vs. 0.227; p = 0.018) could be observed.

CONCLUSIONS

Familial MS differs from sporadic cases with respect to age at onset, multifocal involvement as first clinical event, and conversion into secondary progression. The progression rate of one out of two affected siblings may act as a predictor for the other sib.

Analysis of multiple candidate genes in association with phenotypes of multiple sclerosis

Multiple sclerosis is a heterogeneous neurological disease with varying degrees of severity. The common hypothesis is that susceptibility to multiple sclerosis and its phenotype are caused by a combination of environmental and genetic factors. The genetic part exerts its effect through several genes, each having modest effects.

We evaluated whether disease severity could be predicted by a model based on clinical data and data from a DNA chip. The DNA chip was designed containing several single nucleotide polymorphisms in 44 genes, previously described to be associated with multiple sclerosis.

A total of 605 patients with multiple sclerosis were included in this analysis, using gender, onset type and age at onset as clinical covariates. We correlated 80 single nucleotide polymorphisms to the degree of disease severity using the following three outcome measures: linear Multiple Sclerosis Severity Score, dichotomous Multiple Sclerosis Severity Score (using a cut-off point of 2.5) and time to reach Expanded Disability Status Scale score 6.

Sixty-nine single nucleotide polymorphisms were included in the analysis. No individual single nucleotide polymorphism showed a significant association; however, a combination of single nucleotide polymorphisms significantly improved the prediction of disease severity in addition to the clinical variables. In all three models the Interleukin 2 gene was included, confirming a previously reported modest effect on disease severity. The highest power was obtained using the dichotomized Multiple Sclerosis Severity Score as outcome.

Several single nucleotide polymorphisms showed their added predictive value over the clinical data in the predictive models. These results support our hypothesis that disease severity is determined by clinical variables and genetic influences (through several genes with small effects) in concert.

MGAT5 alters the severity of multiple sclerosis

Multiple Sclerosis (MS) is a genetically complex immune mediated, demyelinating disease of the central nervous system. To date no genetic variants have been unambiguously linked to disease severity. We have conducted a genome wide screen, using Affymetrix Genechip 500K technology, for severity in 1040 MS patients. Two markers within MGAT5, a gene coding for a glycosylation enzyme, were found to be significantly associated with outcome in the screening as well as in an independent population (combined p-values: 2.8 x 10(-6) and 1.5 x 10(-7)).

Anticipation of age at onset in familial multiple sclerosis

BACKGROUND AND OBJECTIVE

Anticipation of age at onset in the younger generations is a widely known characteristic of many diseases with genetic inheritance. This study was performed to assess whether there is anticipation of age at onset in younger generations of familial multiple sclerosis (MS) in a Spanish population and to compare clinical characteristics of familial and sporadic MS.

METHODS

We studied a cohort of 1110 patients diagnosed with MS and followed-up in our MS Unit. Patients were considered as familial MS if they had in their family at least one relative of first or second degree diagnosed with MS. Otherwise, patients were considered to have sporadic MS. We compared the age at onset between relatives from different generations, and we also compared the age at onset of familial and sporadic MS.

RESULTS

A lower age at onset in the younger generations was found (median 22 years vs. 30 years, P < 0.001) and a significant lower age at onset of the disease in familial MS comparing to sporadic MS (median 25 years vs. 29 years, P = 0.042).

CONCLUSIONS

There is an anticipation of the age at onset of MS in the younger generations of patients with familial MS. There is also a lower age at onset in familial versus sporadic MS.

Multiple sclerosis and the major histocompatibility complex

PURPOSE OF REVIEW

Multiple sclerosis (MS) is the most common neurological disease affecting young adults. The cause is unknown, but detailed epidemiological and genetic studies have shown a clear inherited component. We review here some of the recent findings of MS genetics with a particular focus on genes of the major histocompatibility complex (MHC).

RECENT FINDINGS

Recent studies add further complexity to the role of the MHC in MS. Reported MHC associations are complex, involving haplotypes rather than single alleles and may involve epigenetic mechanisms and other modulators of gene expression. MHC class II haplotypes display a hierarchy of risks, including protective effects and epistatic interactions, which together dwarf any non-MHC genetic effect. Genes in the MHC region have been shown to influence disease severity, display parent-of-origin effects and interact with a major environmental candidate for MS, vitamin D.

SUMMARY

The MHC class II association with MS is not as straightforward as previously thought. A complete understanding of the epistatic interactions and epigenetic features of this region will be important to understand disease pathogenesis and likely aid the discovery of new therapeutics.

Mutations in the hemochromatosis gene and the clinical outcome of multiple sclerosis

Multiple sclerosis (MS) is a common inflammatory disease of the central nervous system unsurpassed for its variability in disease outcome. Given a possible role for dysregulation of iron metabolism in MS disease pathogenesis, we investigated whether or not mutations in the HFE gene influence the prognosis of the disease. A cohort of sporadic MS cases, taken from opposite extremes of the putative distribution of long-term outcome using the most stringent clinical criteria to date, was used to determine the role of HFE on MS disease severity. This approach increases the effective sample size by some 40-fold. Genotyping the two sets of MS patients (112 benign and 51 malignant) provided no evidence to suggest that mutations in HFE have any outcome modifying activity, although small effects cannot be ruled out. The frequency of HFE mutations was not different in MS compared to the general population.

Modification of Multiple Sclerosis Phenotypes by African Ancestry at HLA

BACKGROUND

In those with multiple sclerosis (MS), African American individuals have a more severe disease course, an older age at onset, and more often have clinical manifestations restricted to the optic nerves and spinal cord (opticospinal MS) than white persons.

OBJECTIVE

To determine whether genetic variation influences clinical MS patterns.

DESIGN

Retrospective multicenter cohort study.

PARTICIPANTS

Six hundred seventy-three African American and 717 white patients with MS.

MAIN OUTCOME MEASURES

Patients with MS were genotyped for HLA-DRB1 and HLA-DQB1 alleles. The proportion of European ancestry at HLA was estimated by genotyping single-nucleotide polymorphisms with known significant frequency differences in West African and European populations. These genotypes were correlated with the opticospinal disease phenotype, disability measures, and age at onset.

RESULTS

Subjects with DRB1*15 alleles were twice as likely to have typical MS rather than opticospinal MS (P = .001). Of the subjects with opticospinal MS or a history of recurrent transverse myelitis who were seropositive for anti-aquaporin 4 antibodies (approximately 5%), none carried DRB1*15 alleles (P = .008). Independently of DRB1*15, African ancestry at HLA correlated with disability as measured by the Multiple Sclerosis Severity Score (P < .001) and risk of cane dependency (hazard ratio, 1.36; P < .001); DRB1*15 alleles were associated with a 2.1-year earlier age at onset (P < .001).

CONCLUSIONS

These data indicate that the role of HLA in MS is not limited to disease susceptibility but that genes embedded in this locus also influence clinical outcomes.

Genome-wide association analysis of susceptibility and clinical phenotype in multiple sclerosis

Multiple sclerosis (MS), a chronic disorder of the central nervous system and common cause of neurological disability in young adults, is characterized by moderate but complex risk heritability. Here we report the results of a genome-wide association study performed in a 1000 prospective case series of well-characterized individuals with MS and group-matched controls using the Sentrix HumanHap550 BeadChip platform from Illumina. After stringent quality control data filtering, we compared allele frequencies for 551 642 SNPs in 978 cases and 883 controls and assessed genotypic influences on susceptibility, age of onset, disease severity, as well as brain lesion load and normalized brain volume from magnetic resonance imaging exams. A multi-analytical strategy identified 242 susceptibility SNPs exceeding established thresholds of significance, including 65 within the MHC locus in chromosome 6p21.3. Independent replication confirms a role for GPC5, a heparan sulfate proteoglycan, in disease risk. Gene ontology-based analysis shows a functional dichotomy between genes involved in the susceptibility pathway and those affecting the clinical phenotype.

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.

Analysis of 45 candidate genes for disease modifying activity in multiple sclerosis

Multiple sclerosis (MS) is a common inflammatory disease of the central nervous system unsurpassed for its variability in disease outcome. As little is conclusively known about MS disease mechanisms, we have selected a variety of candidate genes that may influence the prognosis of the disease based on their function. A cohort of sporadic MS cases, taken from opposite extremes of the putative distribution of long-term outcome using the most stringent clinical criteria to date, was used to determine the role of on MS disease severity. The MS cases selected represent the prognostic best 5 % (benign MS) and worst 5 % (malignant MS) of cases in terms of clinical outcome assessed by the EDSS. Genotyping the two sets of MS patients (112 benign and 51 malignant) and a replication cohort from Sardinia provided no evidence to suggest that the genes selected have any outcome modifying activity, although small effects of these genes cannot be ruled out.

The genetics of multiple sclerosis: SNPs to pathways to pathogenesis

Multiple sclerosis (MS) is an autoimmune demyelinating disease and a common cause of neurological disability in young adults. The modest heritability of MS reflects complex genetic effects and multifaceted gene-environment interactions. The human leukocyte antigen (HLA) region is the strongest susceptibility locus for MS, but a genome-wide association study recently identified new susceptibility genes. Progress in high-throughput genotyping and sequencing technologies and a better understanding of the structural organization of the human genome, together with powerful brain-imaging techniques that refine the phenotype, suggest that the tools could finally exist to identify the full set of genes influencing the pathogenesis of MS.

CCL5 and CCR5 genotypes modify clinical, radiological and pathological features of multiple sclerosis

Chemokines mediate selective recruitment of leukocyte subsets into the CNS during inflammatory episodes. We hypothesised that functional polymorphisms in CCR5 and CCL5 influence perivascular leukocyte infiltration, inflammation, axonal loss, and remyelination, and disease course. Therefore, we determined genotypes at four possibly functional polymorphisms in CCR5 and CCL5 for 637 patients and 92 brain donors with multiple sclerosis (MS). For a subset of 192 patients, MRI data were available. We found that low-producer allele CCL5-403*G was associated with reduced risk of severe axonal loss, whereas high-producer allele CCL5-403*A was associated with a worse clinical disease course measured by the MS Functional Composite Score and MS Severity Score. Low-producer allele CCR5+303*G was associated with reduced T2 hyperintense and T1 hypointense lesion volumes on MRI, and high-producer allele CCR5+303*A with early age at onset. Furthermore, low-producer allele CCR5Delta32 was associated with reduced T2 lesion volume, lower black hole ratio on MRI, and with a higher percentage of lesions with signs of remyelination, histopathologically. In summary, our multifaceted study supports the notion that polymorphisms in CCL5 and CCR5 modify the course of MS.

Multiple Sclerosis in Keralite siblings after migration to the Middle East: a report of familial Multiple Sclerosis from India

OBJECTIVE

To report Multiple Sclerosis (MS) in two migrant Indian siblings in the Middle East.

BACKGROUND

MS was thought to be rare in the Indian subcontinent, but, of late, with ready availability of Magnetic Resonance Imaging (MRI) scan, evoked potential studies and immunoglobulin estimation in this part of the developing world, there have been several reports of definite cases of MS from India. However familial MS remains hitherto unreported from the Indian subcontinent.

REPORT

A 39-year-old South Indian Hindu female presented with an episode of hemiparesis which remitted with treatment. Three months later she had a relapse in an acute disseminated form, with residual deficits in gait, vision and mental faculties. MRI revealed discrete and confluent plaques in the centrum semiovale. Four years later, her brother was diagnosed to have central demyelinating disease with discrete and confluent plaques in the cervical cord and corona radiata when he presented at age 39 with neck pain and episodic tonic spasms in the lower limbs. Leucodystrophies were ruled out through appropriate biochemical tests. Cases satisfied diagnostic criteria for MS and were confirmed by follow up. HLA associations were studied. Starting a decade after migration from the South Indian state of Kerala to the Middle East, the disease had slow secondary progression in the female but a stable benign course, so far, in the male sibling.

CONCLUSIONS/RELEVANCE

This is the first case report of familial MS from the Indian subcontinent. Onset of MS in South Indian siblings after several years of stay in the Middle East may support aetiological postulations of gene-environment interactions.

Où en sont les études génétiques de la SEP ?

INTRODUCTION

Multiple Sclerosis (MS) is a multifactorial disorder caused by the interaction of environmental factors with a genetic predisposition.

BACKGROUND

The chromosomal region comprising MHC contains one or several genes which contributes from 20 to 50 p. 100 to MS genetic predisposition. Other genes are unknown but are likely to have an individual contribution less than MHC.

PERSPECTIVES AND CONCLUSION

Large DNA collections, high output genotyping facilities, a precise knowledge of the human genome and adequate statistical methods should allow the identification of MS predisposition genes.

Glucocorticoid receptor gene polymorphisms associated with more aggressive disease phenotype in MS

Multiple sclerosis (MS) is a chronic inflammatory and demyelinating disease of the central nervous system, in which unknown environmental factors are thought to trigger disease in genetically susceptible persons. Glucocorticoids (GCs) play an important role in controlling chronic inflammatory diseases, like MS. Three polymorphisms in the glucocorticoid receptor (GR) gene (N363S, ER22/23EK and the Bcl I C/G) have been shown to alter glucocorticoid sensitivity, and therefore may influence disease course. We investigated the influence of these polymorphisms on clinical and MRI parameters. The ER22/23EK polymorphism was associated with a more aggressive MS phenotype, measured both clinically and on MRI.

No effect of APOE and PVRL2 on the clinical outcome of multiple sclerosis

Multiple sclerosis (MS) is a common inflammatory disease of the central nervous system unsurpassed for its variability in disease outcome. Apolipoprotein E (APOE) is involved in neuronal remodelling and several studies have attempted to examine the effect of APOE on MS disease severity, but its function in modifying the course of MS is controversial. It has been suggested recently that PVRL2, not APOE, is the locus on chromosome 19 which influences clinical outcome of MS. A cohort of sporadic MS cases, taken from opposite extremes of the putative distribution of long-term outcome using the most stringent clinical criteria to date, was used to determine the role of APOE and PVRL2 on MS disease severity. The MS cases selected represent the prognostic best 5% (benign MS) and worst 5% (malignant MS) of cases in terms of clinical outcome assessed by the EDSS. Genotyping the two sets of MS patients (112 benign and 51 malignant) and a replication cohort from Sardinia provided no evidence to suggest that APOE or PVRL2 have any outcome modifying activity. We conclude that APOE and PVRL2 have little or no effect on the clinical outcome of MS.

The neurobiology of multiple sclerosis: genes, inflammation, and neurodegeneration

The autoimmune model of multiple sclerosis (MS) pathogenesis provided for many years a useful but incomplete conceptual framework for understanding the complex array of factors that lead to the loss of immune homeostasis, myelin and axonal injury, and progressive neurological symptoms. The availability of novel tools in molecular neurogenetics and increasingly sophisticated neuroimaging technologies, together with the revitalization of MS neuropathology, has created a new paradigm for the multidisciplinary study of this disease. This is reflected by the growing resolution of the MS genomic map, discovery of delicate inflammatory networks that are perturbed in MS, identification of mediators of demyelination, and recognition that cumulative axonal loss and neuronal injury are the histological correlates of neurological disability. Together, these advances have set the stage for the development of therapeutic approaches designed to target the demyelinating and neurodegenerative components of the disease and promote repair.

PADI4 gene in multiple sclerosis: A family-based association study

In multiple sclerosis (MS) MBP is heavily citrullinated by peptidylarginine deiminase (PAD). This post-translational modification may be crucial for its pathogenesis. PADI4 is the isoform expressed in inflammatory infiltrates. The aim of this study was to analyse the role of PADI4 gene in conferring susceptibility to MS, by means of a family-based association study, testing three SNPs by RFLP. No association was found either with single SNPs or haplotypes. Similarly no significant association was detected partitioning the patients according to DRB1*15 positivity or disease severity. These results do not support a major role of the PADI4 gene, but further studies may contribute to clarify the genetic factors that regulate deimination.

Analysing the effect of candidate genes on complex traits: an application in multiple sclerosis

The conventional approach of candidate gene studies in complex diseases is to look at the effect of one gene at a time. However, as the outcome of chronic diseases is influenced by a large number of alleles, simultaneous analysis is needed. We demonstrate the application of multivariate regression and cluster analysis to a multiple sclerosis (MS) dataset with genotypes for 489 patients at 11 candidate genes selected on their involvement in the immune response. Using multivariate regression, we observed that different sets of genes were associated with different disease characteristics that reflect different aspects of disease. Out of 15 polymorphisms, we identified one that contributed to the severity of disease. In addition, the set of 15 polymorphisms was predictive for yearly increase in lesion volume as seen on T1-weighted MRI (p=0.044). From this set, no individual polymorphisms could be identified after adjustment for multiple hypotheses testing. By means of a cluster analysis, we aimed to identify subgroups of patients with different pathogenic subtypes of MS on the basis of their genetic profile. We constructed genetic profiles from the genotypes at the 11 candidate genes. The approach proved to be feasible. We observed three clusters in the sample of patients. In this study, we observed no significant differences in the usual clinical and MRI outcome measures between the different clusters. However, a number of consistent trends indicated that this clustering might be related to the course of disease. With a larger number of genes regulating the course of disease, we may be able to identify clinically relevant clusters. The analyses are easily implemented and will be applicable to candidate gene studies of complex traits in general.

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.

Genomics and new targets for multiple sclerosis

Compelling epidemiological 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 MS individuals respond 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 environmental influences. Equally significant, it is likely that locus heterogeneity exists, whereby specific genes influence susceptibility and pathogenesis in some individuals but not in others.

Intercellular adhesion molecule-1: a protective haplotype against multiple sclerosis

Intercellular adhesion molecule-1 (ICAM-1) and its receptors are adhesion molecules that play a key role in the transmigration of inflammatory cells through the blood-brain barrier, one of the earliest events in multiple sclerosis (MS), which leads to demyelination in the central nervous system. To investigate the role of genes encoding ICAM-1 and its receptors, we used a strategy of genetic linkage and association in 439 case-parent MS families of French origin, well characterized according to HLA status and severity. We demonstrate that the genes encoding ICAM-1 receptors do not influence MS susceptibility or severity. ICAM-1 had a modest, but significant effect on MS genetic susceptibility, independent of HLA and disease severity. We observed a rare, and an as yet unreported, ICAM-1 gene haplotype defined by amino acids K469 and R241 that was never transmitted to patients suggesting a protective effect against MS in our population.

Multiple sclerosis: severity and progression rate in African Americans compared with whites

OBJECTIVE

Although epidemiology indicates that multiple sclerosis is more common among whites than African Americans, the course of disease may be more aggressive among African Americans. This study examines disease course in a large multiple sclerosis clinic population.

DESIGN

A case-controlled, retrospective record review compared the severity of multiple sclerosis for African Americans and for whites. Because the baseline demographics of the two groups differed, we performed analyses of multiple subgroups in an attempt to control for various characteristics.

RESULTS

Consistent evidence of more disability in African Americans compared with whites was found, although subgroups were often too small to establish statistical significance. African Americans had a higher mean Expanded Disability Status Scale score than whites in a subgroup selected to minimize differences in access to care and disease perceptions. African Americans reported limb weakness as a presenting symptom of multiple sclerosis more frequently than did whites. When patients were followed at our multiple sclerosis center, rates of disease progression were nearly identical.

CONCLUSIONS

More African Americans than whites experience pyramidal system involvement early in multiple sclerosis, leading to greater disability as measured by the ambulation-sensitive Expanded Disability Status Scale. Once patients have moderate difficulty walking, the rate of progression is the same for both groups, albeit occurring at a later age for whites than for African Americans.

Inflammation in multiple sclerosis: the good, the bad, and the complex

Inflammation has always been thought of as detrimental in the pathophysiology of multiple sclerosis (MS). However, emerging genetic data, magnetic-resonance-imaging studies, and immunopathological evidence challenge this simplistic view. The evidence leads to the conclusion that inflammation is tightly regulated, and that its net effect may be beneficial in MS, thus explaining some of the results from recent trials of anti-inflammatory agents. We argue that the use of anti-inflammatory drugs to treat MS may not be appropriate in all cases. Precise identification of the inflammatory pathways to be targeted in the different phases of the disease and the timing of such interventions are therefore crucial.

APOE genotypes and disease severity in multiple sclerosis

Apolipoprotein E (opoE) is involved in the transport of lipids necessary for membrane repair and is encoded by a gene on chromosome 19q13, a region positive for linkage in two multiple sclerosis (MS) genome-wide screens. The APOE epsilon4 allele confers susceptibility to both familial and sporadic Alzheimer's disease (AD). Carriage of epsilon4 is associated with defective dendritic remodeling in AD, and with unfavorable clinical outcome in head trauma and cerebrovascular disease. According to the results of previous studies, APOE epsilon4 does not increase the risk of developing MS, but it may influence disease progression and ultimate disability. From a total cohort of over 900 MS patients, we compared APOE epsilon2-4 genotypes in, roughly, the cohort's least disabled and most disabled septiles. 'Benign MS' (n=124) was defined as an Expanded Disability Status Scale (EDSS) score of 3.0 or less, despite at least 10 years of disease duration, and 'severe MS' (n=140) as the attainment of an EDSS score of 6.0 within 8 years of disease onset. We found no significant differences in genotype or phenotype frequencies between the benign-MS and severe-MS septiles; however, the risk conferred by epsilon4 rose progressively upon comparison of carriage rates in more narrowly defined anti-podal quantiles.

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.

Genetic variation in the transforming growth factor beta1 gene in multiple sclerosis

Transforming growth factor beta1 (TGFbeta1) is a Th2 cytokine encoded on chromosome 19q13, a region possibly linked to multiple sclerosis (MS). TGFbeta1 exerts favorable effects on experimental allergic encephalomyelitis. We performed a comprehensive search for genetic variants in this gene in 122 population-based sporadic cases of MS. We detected six variants, including three missense variants. We tested for association of the variants with susceptibility and course of MS and for linkage and transmission disequilibrium in a family series consisting of 395 samples in 59 pedigrees. Genetic variation in TGFB1 does not appear to contribute in a major way to susceptibility to MS.

[Multiple sclerosis: pathogenesis and manifestations in children]

Multiple sclerosis (MS) is rare in children and occurs exceptionally before ten years. Sex ratio (girl/boy) is around 2.5 to 3, higher than in adults. Brain stem dysfunction and meningeal symptoms are more commonly first manifestations of the disease than in adults. Optic neuritis is also a frequent early manifestation. The etiology of the disease remains unclear and none of the advanced hypotheses (infectious, genetic, environmental) can by themselves explain its occurrence. There is a genetic susceptibility which is probably linked to many genes leading to a low related risk (less than two). A viral trigger mechanism in a person with a genetic predisposition is possible. New therapies result from a better understanding of the closed immune mechanisms of the disease.

Multiple sclerosis and oligodendroglioma

Two cases of multiple sclerosis (MS) and oligodendroglioma are reviewed, increasing the total number of reported cases to II. In this series, the clinical onset of MS preceded the discovery of the tumor by a mean of 15 years. No distinguishing features of oligodendroglioma were characteristic of MS-associated cases. However, there was an overrepresentation of benign MS. Although this could result from biased ascertainment, other possibilities, including effective remyelination mediated by mitotically active oligodendrocytes, or secretion of immunosuppressive cytokines by the tumor tissue, cannot be excluded. It is likely that the coexistence of MS and oligodendroglioma is due to chance alone, nonetheless the possibility that glioma derived factors can moderate the disease course in MS is deserving of further study.