Multiple sclerosis in men: management considerations.

Multiple sclerosis (MS) is a lifelong disease typically affecting individuals in young to middle adulthood. There are recognized sex differences in MS onset and clinical course. MS affects approximately three times more women than men, thus resulting in less attention to the male experience (i.e. diagnosis, management, societal dimensions). Here, we review current scientific evidence on sex differences in MS risk and course, highlight potential sources of bias, and suggest avenues of further inquiry. We then describe what is known about male experiences with MS diagnosis, treatment, and symptom management (particularly mood and sexual function). Finally, we consider ways in which healthcare providers might engage male patients in the broader aspects of living with MS (e.g. familial and societal relationships) to influence their long-term quality of life (QOL). When possible, we draw from published sources to underscore our collective clinical and scientific experiences.

Birth outcomes of pregnancies fathered by men with multiple sclerosis.

We linked several population-based clinical and health administrative databases in British Columbia, Canada. We identified and compared birth outcomes of pregnancies fathered by men with multiple sclerosis (MS) (n=202) and men from a frequency-matched general population cohort (n=981) between 1996 and 2010. Using multivariate models, we analyzed the association of paternal MS, disease duration at conception and disability (as measured by the Expanded Disability Status Scale) with birth weight and gestational age. Paternal MS and MS-related clinical factors were not significantly associated with birth outcomes (p>0.05). This study provides assurance to expecting fathers with MS and their families.

Reproductive decision making after the diagnosis of multiple sclerosis (MS).

OBJECTIVE: This study aimed to determine reproductive practices and attitudes of North Americans diagnosed with multiple sclerosis (MS) and the reasons for their reproductive decision making. METHODS: A self-administered questionnaire on reproductive practices was mailed to 13,312 registrants of the North American Research Committee on Multiple Sclerosis (NARCOMS) database who met inclusion criteria for the study. Completed questionnaires were then returned to the authors in an anonymous format for analysis. RESULTS: Among 5949 participants, the majority of respondents (79.1%) did not become pregnant following diagnosis of MS. Of these, 34.5% cited MS-related reasons for this decision. The most common MS-related reasons were symptoms interfering with parenting (71.2%), followed by concerns of burdening partner (50.7%) and of children inheriting MS (34.7%). The most common reason unrelated to MS for not having children was that they already have a "completed family" (55.6%). Of the 20.9% of participants who decided to become pregnant (or father a pregnancy) following a diagnosis of MS, 49.5% had two or more pregnancies. CONCLUSION: This study indicates that an MS diagnosis does not completely deter the consideration of childbearing in MS patients of both genders.

Mitochondrial DNA haplogroups and mutations in children with acquired central demyelination.

OBJECTIVE: We investigated mitochondrial DNA (mtDNA) variants in children with a first episode of acquired demyelinating syndromes (PD-ADS) of the CNS and their relationship to disease phenotype, including subsequent diagnosis of multiple sclerosis (MS). METHODS: This exploratory analysis included the initial 213 children with PD-ADS in the prospective Canadian Pediatric Demyelinating Study and 166 matched healthy sibling controls from the Canadian Autism Genome Project. A total of 31 single nucleotide polymorphisms (SNPs) were analyzed, including haplogroup-defining SNPs and mtDNA variants previously reported to be associated with MS. RESULTS: Primary Leber hereditary optic neuropathy (LHON) mutations and other known pathogenic mtDNA mutations were absent in both patients with pediatric acquired demyelinating syndromes and controls. The 13708A haplogroup J-associated variant, previously linked to adult MS, was more frequent among subjects with PD-ADS (13.0%) compared to controls (6.2%; odds ratio [OR] 2.27; 95% confidence interval [CI] 1.06 to 4.83) and haplogroup M was associated with an earlier age at onset of PD-ADS (-1.74 years; 95% CI -3.33 to -0.07). In contrast, the haplogroup cluster UKJT, as well as 3 other SNPs, were each associated with a lower risk of PD-ADS. A total of 33 subjects with PD-ADS were diagnosed with MS during a mean follow-up period of 3.11 ± 1.14 (SD) years. No single SNP was associated with the risk of subsequent diagnosis of MS. However, haplogroup H was associated with an increased risk of MS (OR 2.60; 95% CI 1.21 to 5.55). CONCLUSION: These data suggest an association between mtDNA variants and the risk of PD-ADS and of a subsequent MS diagnosis. Replication of these findings in an independent population of subjects with PD-ADS is required.

HLA-DRB1 confers increased risk of pediatric-onset MS in children with acquired demyelination.

BACKGROUND: Multiple sclerosis (MS) in the pediatric age group is being increasingly recognized. In adults, complex interactions between genetic and environmental factors contribute to risk and the major genetic component of MS susceptibility localizes to the major histocompatibility complex (human leukocyte antigen [HLA]). Whether HLA alleles predict MS in at-risk children presenting with acquired demyelinating syndromes (ADS) of the CNS is unknown. METHODS: HLA-DRB1 alleles were typed using an allele-specific PCR amplification method on samples from 266 children presenting with ADS enrolled in the prospective Canadian Pediatric Demyelinating Disease Study and from 196 healthy controls. RESULTS: Sixty-four of 266 children with ADS met established criteria for a diagnosis of MS during a mean follow-up of 3.2 ± 1.5 years. Children harboring DRB1*15 alleles were more likely to be diagnosed with MS (χ(2) = 12.2, p < 0.001; OR = 2.7), an observation strengthened by children of European ancestry (χ(2) = 10.5, p = 0.001; OR = 3.3). DRB1*15 allele frequencies in children with ADS of European ancestry subsequently diagnosed with MS were greater than in children with monophasic ADS (χ(2) = 10.7, p = 0.001) or healthy controls (χ(2) = 12.5, p < 0.001). The proportion of children with non-European ancestry diagnosed with MS was not influenced by DRB1*15 status. CONCLUSION: DRB1*15 alleles confer increased susceptibility to pediatric-onset MS, supporting a fundamental similarity in genetic contribution to MS risk in both pediatric- and adult-onset disease. The specificity of the DRB1*15 risk allele for children with subsequent MS diagnosis, but not for all children with ADS, indicates that the risk conveyed by DRB1*15 relates to chronic CNS disease (MS), rather than acquired demyelination in general.

Association of UV radiation with multiple sclerosis prevalence and sex ratio in France.

BACKGROUND: French farmers and their families constitute an informative population to study multiple sclerosis (MS) prevalence and related epidemiology. We carried out an ecological study to evaluate the association of MS prevalence and ultraviolet (UV) radiation, a candidate climatologic risk factor. METHODS: Mean annual and winter (December-March) UVB irradiation values were systematically compared to MS prevalence rates in corresponding regions of France. UVB data were obtained from the solar radiation database (SoDa) service and prevalence rates from previously published data on 2,667 MS cases registered with the national farmer health insurance system, Mutualité Sociale Agricole (MSA). Pearson correlation was used to examine the relationship of annual and winter UVB values with MS prevalence. Male and female prevalence were also analyzed separately. Linear regression was used to test for interaction of annual and winter UVB with sex in predicting MS prevalence. RESULTS: There was a strong association between MS prevalence and annual mean UVB irradiation (r = -0.80, p < 0.001) and average winter UVB (r = -0.87, p < 0.001). Both female (r = -0.76, p < 0.001) and male (r = -0.46, p = 0.032) prevalence rates were correlated with annual UVB. Regression modeling showed that the effect of UVB on prevalence rates differed by sex; the interaction effect was significant for both annual UVB (p = 0.003) and winter UVB (p = 0.002). CONCLUSIONS: The findings suggest that regional UVB radiation is predictive of corresponding MS prevalence rates and supports the hypothesis that sunlight exposure influences MS risk. The evidence also supports a potential role for gender-specific effects of UVB exposure.

Revisiting the T-cell receptor alpha/delta locus and possible associations with multiple sclerosis.

A role for T cells in the pathogenesis of multiple sclerosis (MS) is well supported, evidenced by myriad immunological studies, as well as the unequivocal genetic influence of the major histocompatibility complex (MHC). Despite many attempts, no convincing genetic associations have been made between T-cell receptor (TCR) gene loci and MS. However, these studies may not be definitive because of small sample sizes and under-representative marker coverage of the chromosomal regions being investigated. To explore potential roles between the TCR alpha locus and MS, we have genotyped a large family-based cohort, including 1360 affected individuals and 1659 of their unaffected first-degree relatives, at 40 single-nucleotide polymorphism (SNP) markers within the TCR alpha/delta locus. This represents the largest TCR alpha-MS study to date. From this screen, we identified three potential loci of interest in TCR alpha variable and constant gene regions using the transmission disequilibrium test. Although SNPs implicating each of these regions of interest will require genotyping in independent replication cohorts, these findings suggest a role for TCR gene polymorphisms in MS susceptibility. In the context of these findings we review the evidence.

MHC transmission: insights into gender bias in MS susceptibility.

OBJECTIVE: Major histocompatibility complex (MHC) genes dominate genetic susceptibility factors in multiple sclerosis (MS). Given the general consensus that incidence and prevalence of MS has been rising and specifically in women, we evaluated MHC-gender interactions. METHODS: In a large family-based cohort consisting of 7,093 individuals (2,127 affected individuals) from 1,055 MS families, we examined MHC transmission by family structure and gender stratified by genetic distance of affected relatives from the MS proband. RESULTS: We found that affected individuals with HLA-DRB1*15-positive genotypes have higher female-to-male ratios as compared with affected individuals with HLA-DRB1*15-negative genotypes (χ(2) = 9.97, p = 0.0015) with the exception of multiplex families with 3 or more affected across 2 generations. Transmission disequilibrium test results show that HLA-DRB1*15 transmission was more distorted in collateral families vs nuclear families (χ(2) = 8.030, p = 0.0046), exclusively in affected female-female pairs (χ(2) = 7.81, p = 0.0051), but not in mixed gender pairs (χ(2) = 1.58, p = 0.21) or matched male pairs (Fisher p = 0.21). CONCLUSIONS: These observations implicate the MHC as the site of interactions and modifications mediating the female-to-male gender ratio in MS and its progressive increase. They further suggest this occurs via gene-environment interactions and epigenetic modifications in this region. The difference between collateral and nuclear families provides some insight into the inheritance, decay, and gender specificity of putative epigenetic marks.

Sex ratio of multiple sclerosis and clinical phenotype.

BACKGROUND AND PURPOSE: In a longitudinal population-based dataset of patients with multiple sclerosis (MS), we have previously observed a substantial increase in the female to male sex ratio in Canada over the last 50 years. Here, we aimed to determine whether this change in sex ratio is related to the clinical course of MS. METHODS: We calculated sex ratios by birth year in 11 868 patients with relapsing-remitting (RR) MS and 2825 patients with primary progressive (PP) MS identified as part of the Canadian Collaborative Project on the Genetic Susceptibility to MS. RESULTS: Year of birth was a significant predictor for sex ratio in RR MS (P < 0.0001, chi(2) = 21.2; Spearman's rank correlation r = 0.67), but not for PP MS (P = 0.44, chi(2) = 0.6; Spearman's rank correlation r = 0.11). CONCLUSIONS: An increase in the number of female RR MS patients over time accounts for the increasing sex ratio of MS. This has implications for pathogenesis, for assessment of clinical trial results and for disease prevention. The factors underlying the selective increase in MS in females need to be uncovered.

Effect of immigration on multiple sclerosis sex ratio in Canada: the Canadian Collaborative Study.

BACKGROUND: The ratio of female to male (F:M) multiple sclerosis (MS) cases varies geographically, generally being greater in areas of high prevalence. In many regions, including Canada, rising MS incidence in women has been implied by the marked increase in F:M ratio. METHODS: We examined the F:M ratio over time in MS patients in the Canadian Collaborative Study born outside Canada, with onset postmigration (n = 2531). We compared the trends to native-born Canadians, by region of origin and age at migration. RESULTS: Regression analysis showed that year of birth (YOB) was a significant predictor of sex ratio in immigrants (chi(2) = 21.4, p<0.001 correlation r = 0.61). The rate of change in sex ratio was increasing in all migrant subgroups (by a factor of 1.16 per 10-year period, p<0.001), with the steepest increase observed in those from Southern Europe (1.27/10 years, p<0.001). The overall immigrant F:M ratio was 2.17, but varied by country of origin. It was significantly lower in migrants from Southern Europe compared with Northern Europe or USA (1.89 vs 2.14 and 2.86, p = 0.023 and p = 0.0003, respectively). Increasing age at immigration was associated with decreasing sex ratio (p = 0.041). The sex ratio of individuals migrating <21 was significantly higher than those migrating > or =21 (2.79 vs 1.96, p = 0.004). CONCLUSIONS: MS sex ratio in immigrants to Canada is increasing but variable by region of origin and influenced by age at migration. The findings highlight the importance of environmental effect(s) in MS risk, which are likely gender-specific.

HLA-DRB1 and month of birth in multiple sclerosis.

BACKGROUND: Multiple sclerosis (MS) displays a month-of-birth effect, with an excess of individuals being born in the spring and a deficit in the winter. This effect was shown to be more pronounced in familial cases of MS. In the present study, we investigated whether this month-of-birth association has any relation to the principal MS susceptibility gene, HLA-DRB1. METHODS: A total of 4,834 patients with MS, 4,056 controls, and 659 unaffected siblings from Canada, Sweden, and Norway were genotyped for the HLA-DRB1 gene. Month of birth was compared for patients, controls, and unaffected siblings with and without the MS risk allele HLA-DRB1*15. RESULTS: Significantly fewer patients with MS carrying the HLA-DRB1*15 risk allele were born in November compared with patients not carrying this allele (p = 0.02). Additionally, patients with MS carrying HLA-DRB1*15 had a higher number of April births compared with patients with MS not carrying HLA-DRB1*15 (p = 0.004). These differences were not present in controls or unaffected siblings. CONCLUSIONS: Month of birth, HLA-DRB1 genotype, and risk of multiple sclerosis are associated. The interaction of a seasonal risk factor with loci at or near HLA-DRB1 during gestation or shortly after birth is implicated.

European Charcot Foundation Lecture: the natural history of multiple sclerosis and gender.

The role of gender in the natural history of multiple sclerosis (MS) is multi-faceted. Earliest debate on this topic was about the sex ratio (female:male) among affected individuals. It was only clearly shown within the last 4 decades that females are more often affected. The sex ratio continues to intrigue researchers. An observed increase in the sex ratio among more recently born MS patients has now been taken as a clear indication that the rate of MS is truly increasing in many geographical areas. This temporal increase in females has been relatively rapid, implicating environmental rather than genetic risk factors. Gender issues in MS expand beyond the scope of sex ratio. Gender has an impact on various aspects of MS, including age of onset, "parent-of-origin" effects (seen in half-siblings, twin sibships, avuncular pairs, transmission of HLA haplotype), recurrence risks for relatives of MS patients and the topic of reproduction when one parent has MS. Gender issues can also confound data collection and analyses with respect to studies on comorbidity, risk factors and family history. In fact, it has now been clearly validated and quantified that among persons with MS, there is a sex-specificity of recall and reporting bias as well a greater female awareness of medical history.

Parent-of-origin effect in multiple sclerosis: observations from interracial matings.

BACKGROUND: Multiple sclerosis (MS) is a complex neurologic disease with a striking geographical distribution. In Canada, prevalence is high in Caucasians of Northern European ancestry and uncommon in North American Aboriginals, many of whom now have Caucasian admixture. METHODS: The population-based Canadian Collaborative Project on the Genetic Susceptibility to MS provided the characteristics of 58 individuals with 1 Caucasian and 1 North American Aboriginal parent from a database of 30,000 MS index cases. RESULTS: We found that MS index cases with a Caucasian mother and a North American Aboriginal father had a higher sib recurrence risk and greater F:M sex ratio (p = 0.043) than patients with a North American Aboriginal mother and Caucasian father. CONCLUSIONS: Maternal parent-of-origin effects in multiple sclerosis disease etiology previously seen in studies of half-siblings and avuncular pairs are also seen in Caucasian-North American Aboriginal admixture matings and warrant further investigation. A differential influence of maternal risk transmission on the sex ratio of affected offspring is implied. The method of analysis used may have broader implications for detection of parent-of-origin effects in admixture cohorts.

Risk alleles for multiple sclerosis in multiplex families.

OBJECTIVE: We assessed the hypotheses that non-major histocompatibility complex multiple sclerosis (MS) susceptibility loci would be common to sporadic cases and multiplex families, that they would have larger effects in multiplex families, and that the aggregation of susceptibility loci contributes to the increased prevalence of MS in such families. METHODS: A set of 43 multiplex families comprising 732 individuals and 211 affected subjects was genotyped for 13 MS candidate genes identified by genome-wide association. A control data set of 182 healthy individuals was also genotyped to perform a case-control analysis alongside the family-based pedigree disequilibrium association test, although this may have been underpowered. RESULTS: An effect of the IL2RA and CD58 loci was shown in multiplex families as in sporadic MS. The aggregate of the IL2RA, IL7R, EVI5, KIAA0350, and CD58 risk genotypes in affected individuals from multiplex families was found to be notably different from controls (chi(2) = 112, p = 1 x 10(-22)). CONCLUSIONS: Although differences between individual families can only be suggested, the aggregate results in multiplex families demonstrate effect sizes that are increased as compared with those reported in previous studies for sporadic cases. In addition, they imply that concentrations of susceptibility alleles at IL2RA, IL7R, EVI5, KIAA0350, and CD58 are partly responsible for the heightened prevalence of multiple sclerosis within multiplex families.

Age of puberty and the risk of multiple sclerosis: a population based study.

BACKGROUND AND PURPOSE: Genetic and environmental factors have important roles in multiple sclerosis (MS) susceptibility. Given a potential role for sex hormones in MS, we have investigated whether or not the age of puberty influences the risk of developing MS in a population-based cohort. METHODS: We identified 5493 MS index cases and 1759 spousal controls with age of puberty information from the Canadian Collaborative Project on Genetic Susceptibility to MS. Age of puberty was compared between index cases and controls, and any effect of age of puberty on the age of onset of MS was also investigated. RESULTS: There were no significant differences between male index cases and controls with respect to age of puberty, P = 0.70. However, a significant difference was observed between female index cases and female controls, with average age of puberty being 12.4 and 12.6 years respectively, P = 0.00017, providing a relative risk decrease of 0.9 per year increase of age of puberty. There was no effect of the age of puberty on the age of MS onset in either sex. CONCLUSIONS: Earlier age at menarche increases the risk of MS in women. Whether this association is a surrogate for a disease causative factor or directly involved in MS disease aetiology needs to be uncovered.

Parent-of-origin effects in MS: observations from avuncular pairs.

BACKGROUND: Multiple sclerosis (MS) is a complex neurologic disease of unknown etiology and inheritance pattern, but with increasing incidence among females. The study of aunt/uncle-niece/nephew (AUNN) pairs has potential to shed light on the on complex trait inheritance as this group can be divided into eight different pair types by gender, MS status, and parent of origin. METHODS: Using a cohort of 807 avuncular MS families with 938 affected AUNN pairs ascertained from a longitudinal, population-based Canadian database, we examined differential MS transmission by separating affected pairs into likely maternal and paternal trait origin. RESULTS: We observed an increased number of avuncular pairs connected through unaffected mothers compared to unaffected fathers (p = 0.008). To restrict confounders introduced by families with multiple pairs the overall number of maternal and paternal families were compared, to reveal a significantly higher number of maternal families (p = 0.038). Female-to-male sex ratios were higher among affected nieces/nephews when compared to the sex ratio for aunts/uncles (0.00042). CONCLUSIONS: This observation independently confirms previous findings of a "maternal parent-of-origin" effect in multiple sclerosis (MS) susceptibility. These findings highlight the special contribution that can be derived from avuncular pairs. These underutilized pairings can compare transmission by the gender of affected aunt-uncle, the unaffected transmitting parent, and by that of the affected offspring. This strategy may be especially profitable in diseases where parent-of-origin effects are being sought. These findings also independently confirm the increasing rate of MS in females, demonstrating that familial cases are influenced by the same environmental factors as the general MS population.

A genome scan in a single pedigree with a high prevalence of multiple sclerosis.

BACKGROUND: Multiple sclerosis (MS) is a disease that is widely believed to be autoimmune in nature. Genetic-epidemiological studies implicate susceptibility genes in the pathogenesis of MS, although non-MHC susceptibility linkages have been difficult to confirm. Insight into pathways that are intrinsic to other complex diseases has come from the genetic analysis of large, autosomal-dominant kindreds. Here, we present a genetic study of a large and unique kindred in which MS appears to follow an autosomal-dominant pattern of inheritance, with consistent penetrance in four generations. METHODS: Eighty-two individuals of this 370-member family were genotyped with 681 microsatellite markers spanning the genome, with an average spacing of 5.3 cM. RESULTS: Parametric linkage analysis was performed and no significant LOD score (LOD >3.3) was observed. For a rare dominant disease model with reduced penetrance, 99.6% of the genome was excluded at a LOD score <-1 and 96% at a LOD score <-2. The HLA-DRB1 candidate gene was also genotyped by allele-specific methods. In each instance where at least one parent was positive for HLA-DRB1*15, one or more HLA-DRB1*15 alleles were transmitted to the affected offspring (11/11). HLA-DRB1*15 was transmitted equally from both the familial and the married-in parents and therefore this locus does not appear to be an autosomal-dominant acting gene in this family but an important modifier of risk. CONCLUSIONS: These results further stress the importance of the HLA-DRB1*15-bearing haplotype in determining MS susceptibility. Furthermore, this study highlights the complexity of MS genetics, even in the presence of a single family, seemingly segregating MS as an autosomal-dominant trait.

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.