HLA-DRB1 and tumor necrosis factor gene polymorphisms in Japanese patients with multiple sclerosis

HLA-DPB1*0501 is not uniquely associated with opticospinal multiple sclerosis in Japanese patients. Important role of DPB1*0301

Apart from its unique lesion distribution pattern, the opticospinal form of multiple sclerosis (OSMS) is distinct among Japanese patients who satisfy the diagnostic criteria of MS. OSMS has been suggested to be strongly associated with HLA-DPB1*0501 in Japanese. However, association of DPB1*0301 with non-OSMS and lack of DPB1*0301 in OSMS were also reported. To verify the role of DPB1*0501 and DPB1*0301 in Japanese MS patients we determined the frequencies of these alleles in 26 patients with OSMS, 167 with non-OSMS and 156 normal subjects, who were all residents of Hokkaido, the northernmost island of Japan. All (100%) OSMS were negative for DPB1*0301 while 32 (19%) of the non-OSMS were positive for the allele. In DPB1*0301-negatives, the frequencies of DPB1*0501 in OSMS (85%) and non-OSMS (82%) were similar, but both were higher than in the controls (66%). In DPB1*0301-positives, the frequency of DPB1*0501 was low but similar in non-OSMS (12/32; 38%) and controls (6/14; 43%). Periventricular white matter lesions (PVL) were noted in 31 of 32 (97%) DPB1*0301-positive non-OSMS patients but in only 22 out of 135 (16%) DPB1*0301-negative non-OSMS patients and two out of 26 (8%) OSMS patients. Our findings indicate that DPB1*0501 plays an important role in the development of MS in general, but not in OSMS. The strong association of DPB1*0501 with OSMS may be due to the over-representation of the DPB1*0301 allele among individuals in the non-OSMS group. In addition, DPB1*0301 might be relevant to the development of periventricular lesions in Japanese patients with MS.

Genomewide admixture study in Mexican Mestizos with multiple sclerosis

BACKGROUND

Multiple sclerosis (MS) is a complex immune-mediated disease. It has been suggested that genetic factors could explain differences in the prevalence among ethnic groups. To know whether genetic ancestry is a potential risk factor for MS in Mexican patients and to identify candidate genes for the susceptibility to the disease we conducted an initial trial of genome-wide analysis.

METHODS

29 patients with diagnosis of definitive MS and 132 unrelated healthy controls were genotyped using the Affymetrix human 6.0 array. After QC procedures, ancestry determination and a preliminary case-control association study were performed.

RESULTS

We identified significant differences in the European ancestry proportion between MS cases and controls (33.1 vs. 25.56, respectively; p=0.0045). Imputation analysis in the MHC region on chromosome 6 showed a signal with a significant level (p<0.00005) on the HLA-DRB region. Additionally, a preliminary association analysis highlighted the ASF1B as novel candidate gene participating in MS.

CONCLUSION

Our data suggest that European ancestry is a risk factor to develop MS in Mexican Mestizo population. Conversely, indigenous ancestry of Asian origin seems to confer protection. Further studies with more MS cases are needed to confirm these findings.

SNP-based analysis of the HLA locus in Japanese multiple sclerosis patients

Although several major histocompatibility complex (MHC)-wide single-nucleotide polymorphism (SNP) studies have been performed in populations of European descent, none have been performed in Asian populations. The objective of this study was to identify human leukocyte antigen (HLA) loci associated with multiple sclerosis (MS) in a Japanese population genotyped for 3534 MHC region SNPs. Using a logistic regression model, two SNPs (MHC Class III SNP rs422951 in the NOTCH4 gene and MHC Class II SNP rs3997849, susceptible alleles A and G, respectively) were independently associated with MS susceptibility (204 patients; 280 controls), two (MHC Class II SNP rs660895 and MHC Class I SNP rs2269704 in the NRM gene, susceptible alleles G and G, respectively) with aquaporin-4- (AQP4-) MS susceptibility (149 patients; 280 controls) and a single SNP (MHC Class II SNP rs1694112, susceptible allele G) was significant when contrasting AQP4+ against AQP4- patients. Haplotype analysis revealed a large susceptible association, likely DRB1*04 or a locus included in the DRB1*04 haplotype, with AQP4- MS, which excluded DRB1*15:01. This study is the largest study of the HLA's contribution to MS in Japanese individuals.

HLA-DR allele polymorphism and multiple sclerosis in Chinese populations: a meta-analysis

BACKGROUND

The association of human leukocyte antigen (HLA) genes and multiple sclerosis (MS) has been extensively investigated in Caucasians, but less so in Oriental races such as Chinese.

OBJECTIVES

To review studies on association of HLA class II alleles with MS in the Chinese population.

METHODS

An extensive search for published studies up to June 2010 was performed in the electronic databases. The meta-analysis facilities in the NCSS statistical package were utilized to analyze the findings in these studies. The odds ratios (ORs) of HLA-DR allele distributions in MS were analyzed against controls.

RESULTS

Eleven case-control studies were identified: nine genotyping and two serotyping studies. Six genotyping studies were suitable for HLA-DRB1 allele meta-analysis, which showed that HLA-DRB1*15 was associated with risk of MS in the combined group (308 cases and 407 controls; OR 1.39) while the HLA-DRB1*09 and HLA-DRB1*0901 alleles were protective. When the equivalent serotypes in these six studies were combined with the results from the two serotyping studies (431 cases and 652 controls) for a meta-analysis of HLA-DR serotypes, HLA-DR2 was a risk factor (OR 1.63) and HLA-DR9 was strongly protective in the combined group (OR 0.64).

CONCLUSIONS

Although limited data are available, our meta-analysis suggests that HLA-DR2/DRB1*15 are also associated with risk of MS in the Chinese population but less strongly so than in Western MS populations, whereas HLA-DR9 alleles appear to confer resistance in this population.

Relationship between Barkhof criteria and the clinical features of multiple sclerosis in northern Japan

We previously reported that the prevalence of multiple sclerosis (MS) in the Tokachi Province of Hokkaido increased from 8.6 to 13.1 per 100,000 individuals between 2001 and 2006. Here, we study the frequency of MS patients who fulfill the Barkhof criteria and identified their common features. All 47 subjects in our previous study, who fulfilled Poser's criteria, were included in this study. Of these, 33 satisfied the Barkhof criteria. In 2006, 9.2 per 100,000 MS patients fulfilled the Barkhof criteria; the percentage of patients who fulfilled these criteria was significantly higher among patients born after 1960 than among those born before 1960 (84.3% and 40.0%, respectively). The proportion of patients with conventional MS (C-MS) who fulfilled the Barkhof criteria was higher than that of patients with opticospinal MS (OS-MS) who fulfilled these criteria (93.9% and 71.4%, respectively). Longitudinally extensive spinal cord lesions (LESCLs) were not associated with the brain lesions defined in the Barkhof criteria (Barkhof brain lesions). In Tokachi Province, the increased percentage of MS patients who fulfill the Barkhof criteria was associated with increased C-MS incidence and an increase in the proportion of C-MS patients with Barkhof brain lesions among people born after 1960.

Association of the HLA-DRB1 alleles with characteristic MRI features of Asian multiple sclerosis

Background

In Asian patients with multiple sclerosis (MS), a paucity of brain lesions and longitudinally extensive spinal cord lesions (LESCLs) extending three or more vertebral segments are characteristic findings on magnetic resonance imaging (MRI). We aimed to disclose possible factors contributing to the development of such MRI features.

Method

Genotyping of HLA-DRB1 and -DPB1 alleles was performed in 121 consecutive Japanese patients with clinically definite MS based on the Poser criteria and 125 healthy controls. Possible factors associated with MRI features were determined by multiple logistic analysis. Patients with MS were classified based on the presence or absence of brain lesions fulfilling the Barkhof criteria (Barkhof brain lesions) and LESCLs. Barkhof brain lesion–negative (−) patients had a markedly lower frequency of HLA-DRB1*0901 than controls ( Pcorr < 0.05), whereas the frequency of DRB1*1501 was increased in the Barkhof brain lesion–positive (+) group, although this increase was not significant after correction. No Barkhof(−)LESCL(+) patients carried DRB1*0901 ( Pcorr < 0.05), despite this being the most common allele in Japanese. The Barkhof(−)LESCL(−) group showed a significant increase in the frequency of DRB1*0405 compared with controls ( Pcorr < 0.05). None of the DPB1 alleles were significantly different among the groups. Using multiple logistic analysis, the absence of oligoclonal bands was positively associated with an absence of Barkhof brain lesions, whereas a higher EDSS score was positively associated with the presence of LESCLs; however, the presence of anti-aquaporin-4 antibodies was not associated with either feature.

Conclusion

The characteristic MRI features in Asians are partly related to distinct HLA-DRB1 gene alleles and an absence of oligoclonal bands.

The immunogenetics of multiple sclerosis

The discoveries in the 1970s of strong associations between various diseases and certain human leukocyte antigen (HLA) factors were a revolution within genetic epidemiology in the last century by demonstrating for the first time how genetic markers can help unravel the genetics of disorders with complex genetic backgrounds. HLA controls immune response genes and HLA associations indicate the involvement of autoimmunity. Multiple sclerosis (MS) was one of the first conditions proven to be HLA associated involving primarily HLA class II factors. We review how HLA studies give fundamental information on the genetics of the susceptibility to MS, on the importance of linkage disequilibrium in association studies, and on the pathogenesis of MS. The HLA-DRB1*1501 molecule may explain about 50% of MS cases and its role in the pathogenesis is supported by studies of transgenic mice. Studies of polymorphic non-HLA genetic markers are discussed based on linkage studies and candidate gene approaches including complete genome scans. No other markers have so far rivaled the importance of HLA in the genetic susceptibility to MS. Recently, large international collaborations provided strong evidence for the involvement of polymorphism of two cytokine receptor genes in the pathogenesis of MS: the interleukin 7 receptor alpha chain gene (IL7RA) on chromosome 5p13 and the interleukin 2 receptor alpha chain gene (IL2RA (=CD25)) on chromosome 10p15. It is estimated that the C allele of a single nucleotide polymorphism, rs6897932, within the alternative spliced exon 6 of IL7RA is involved in about 30% of MS cases.

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.

Roles of DRB1 *1501 and DRB1 *1502 in the pathogenesis of aplastic anemia

OBJECTIVE

Although a number of reports have documented a significantly increased incidence of HLA-DR15 in aplastic anemia (AA), the exact role of HLA-DR15 in the immune mechanisms of AA remains unclear. We herein clarify the difference between DRB1( *)1501 and DRB1( *)1502, the two DRB1 alleles that determine the presentation of HLA-DR15, in the pathophysiology of AA.

MATERIALS AND METHODS

We investigated the relationships of the patients( *) HLA-DRB1 allele with both the presence of a small population of CD55(-)CD59(-) (PNH-type) blood cells and the response to antithymocyte globulin (ATG) plus cyclosporin (CsA) therapy in 140 Japanese AA patients.

RESULTS

Of the 30 different DRB1 alleles, only DRB1( *)1501 (33.6% vs 12.8%, p(c) < 0.01) and DRB1( *)1502 (43.6% vs 24.4%, p(c) < 0.01) displayed significantly higher frequencies among the AA patients than among a control. AA patients possessing HLA-DR15 tended to be old, and especially, the frequency of DRB1( *)1502 in patients 40 years of age and older (52.4%) was markedly higher than that in those younger than 40 years old (16.2%, p(c) < 0.01). Only DRB1( *)1501 was significantly associated with the presence of a small population of PNH-type cells and it also showed a good response to ATG plus CsA therapy in a univariate analysis. A multivariate analysis showed only the presence of a small population of PNH-type cells to be a significant factor associated with a good response to the immunosuppressive therapy (p < 0.01).

CONCLUSIONS

Although both DRB1( *)1501 and DRB1( *)1502 contribute to the development of AA, the methods of contribution differ between the two alleles.

A three-dimensional approach for understanding the spectrum of idiopathic inflammatory demyelinating disorders: importance of the 'attack-related severity' axis

Understanding the spectrum of idiopathic inflammatory demyelinating disorders (IIDD) of the central nervous system is an important issue for accurate diagnosis and advancing research on the pathogenesis as well as treatment strategies, but the nosology and the classification of the IIDD remains confusing. Until now, we have tried to apply each disorder within the spectrum to an adequate co-ordinate on a two-dimensional plane. One axis is clinical course and the other is lesion distribution. We reviewed some disorders of the IIDD spectrum, and our recent findings on the fulminant nature of each attack and the expansion of each lesion, which we called attack-related severity in Japanese multiple sclerosis (MS). From our findings and the literature, attack-related severity appears to be a third important factor, in addition to lesion distribution and clinical course. Introduction of the third axis produces a three-dimensional space for a better understanding of the heterogeneous characteristics of IIDD and 'MS' syndrome, and can advance treatment strategies for these disorders. As severe attacks seem to be relatively common in Asians but rare in the west, ethnic-related heterogeneity should be considered in understanding the spectrum of IIDD, and there is an urgent need to develop a common general concept of the spectrum, especially for MS.

The HLA-B7 allele confers susceptibility to breast cancer in Spanish women

BACKGROUND

Several HLA alleles are associated with susceptibility or protection in breast cancer. The particular allele varies depending on the geographical region. A study in a small group of Spanish patients using serological methods found an association with HLA-B7. We undertook a larger study in southern Spain using molecular biology techniques.

METHODS

Genotype variants of HLA class I and II were typed by PCR-SSP in 132 breast cancer patients and 382 healthy controls.

RESULTS

The frequency of the HLA-B7 allele was increased in the patients compared to the controls (P=0.0019; 95% confidence interval, 1.337-3.409, relative risk=2.135). Bonferroni correction of the P showed it was still significant (P(c)=0.0285).

CONCLUSIONS

These results support previous suggestions that HLA-B7 is associated with the development of breast cancer in our area.

CSF pleocytosis and expansion of spinal lesions in Japanese Multiple sclerosis with special reference to the new diagnostic criteria

New diagnostic criteria for multiple sclerosis (MS) were recently proposed from the international panel on the diagnosis of MS, and they include exclusion criteria, such as lesions extending over more than two vertebral segments on spinal MRI and CSF pleocytosis of more than 50/mm3. We reviewed the clinical features of 158 patients who satisfied the diagnostic criteria for MS except for having the above atypical paraclinical findings. All patients exhibited two or more clinical attacks and objective clinical evidence of multiple lesions without any evidence of other disorders. Thirty-three (20.9%) patients had one or both atypical paraclinical findings. Twenty-one out of the 33 patients were classified as having optico-spinal MS (OSMS), and the other 12 as non-OSMS patients with atypical large expanding or destructive cerebral, cerebellar or brainstem lesions on MRI as well as one or both atypical paraclinical findings. Based on this heterogeneity in clinical findings in MS, there is an urgent need to develop a common general concept of the "MS" syndromes, and the ethnic-related heterogeneity should be considered in the revised criteria for the diagnosis of MS.

Is there a future for TNF promoter polymorphisms?

The in vitro study of TNF promoter polymorphism (SNP) function was stimulated by the numerous case-control (association) studies of the polymorphisms in relation to human disease and the appearance of several studies claiming to show a functional role for these SNPs provided a further impetus to researchers interested in the role of TNF in their disease of interest. In this review we consider case-control studies, concentrating on the autoimmune and inflammatory diseases rheumatoid arthritis, multiple sclerosis, ankylosing spondylitis, and asthma, and on infectious diseases including malaria, hepatitis B and C infection, leprosy and sepsis/septic shock. We also review the available evidence on the functional role of the various TNF promoter polymorphisms. In general, case-control studies have produced mixed results, with little consensus in most cases on whether any TNF polymorphisms are actually associated with disease, although results have been more consistent in the case of infectious diseases, particularly malaria. Functional studies have also produced mixed results but recent work suggests that the much studied -308G/A polymorphism is not functional, while the function of other TNF polymorphisms remains controversial. Studies of the TNF region are increasingly using extended haplotypes that can better capture the variation of the MHC region.

A NOTCH4 association with multiple sclerosis is secondary to HLA-DR*1501

Multiple sclerosis (MS) is a chronic inflammatory disease of the central nervous system (CNS) with supposedly autoimmune features known to be associated with a specific HLA DR-DQ haplotype (DR15, DQ6, or HLDRB1*1501,DRB5*0101,DQA1*0102,DQB1*0602). We have previously reported that the associated haplotype extends to HLA-B and described an independent association with HLA-A alleles in MS. Owing to a complex situation with extensive linkage disequilibria, it is still unclear whether classical HLA genes are responsible or whether associations may be due to other genes in this region. Here, we analyzed an association in MS with the NOTCH4 and TNFalpha (tumor necrosis factor-alpha) genes, located between the HLA-DRB1 gene and the HLA-A gene. For NOTCH4, located 0.4 Mb telomeric to HLA-DRB1, an SNP at position -25 and a trinucleotide repeat were investigated in 181 MS patients, and 180 controls also typed P = 0.027 for HLA-DRB and HLA-A. A modest association was observed (OR = 3.44) with the C-25 allele. However, two-locus analysis revealed that this association was secondary to the classical association with HLA-DRB1. For TNF, located 0.7 Mb telomeric of NOTCH4, SNPs at positions -308 and -238 were studied in the same dataset. We found no association between these TNFalpha gene polymorphisms and MS in this dataset, although there was linkage disequilibrium (LD) between DRB1 and TNF and between HLA-A and TNF. We conclude that alleles of the NOTCH4 and TNFalpha genes are unlikely to be of importance for the susceptibility to MS, although specific alleles of these genes are often carried on the same haplotype as DR15, DQ6.

Attack-related severity: a key factor in understanding the spectrum of idiopathic inflammatory demyelinating disorders

Understanding the spectrum of idiopathic inflammatory demyelinating disorders (IIDD) is a fundamental issue for the diagnosis and treatment of these disorders as well as for the approach to their pathogenesis. The spectrum of IIDD is usually classified according to clinical course and lesion distribution. We compared the demographic features, clinical characteristics, laboratory findings, and genetic backgrounds between 193 Japanese patients with and without clinically or radiographically fulminant attacks who all satisfied the diagnostic criteria for multiple sclerosis (MS). "Fulminant attacks" in the current study represent attack-related clinically or radiologically severe relapses but do not necessarily mean severe disability. Patients with fulminant attacks were clinically and immunogenetically distinct from those free of such attacks, and the previously described characteristics of the opticospinal form of MS (OSMS) or neuromyelitis optica (NMO) were mostly shared by patients with fulminant attacks. HLA profiles were similar among patients with fulminant attacks irrespective of the lesion distributions. The GG homozygous and G alleles of the CTLA4 gene A/G coding SNP at position 49 in exon 1 were significantly more common in patients with fulminant attacks than in those without. Attack-related severity may be an important factor if validated by prospective studies defining criteria and establishing relationships to disease course and treatment regimens.

Molecular analysis of HLA class II-associated susceptibility to neuroinflammatory diseases in Korean children

The work was done to study immunogenetic peculiarities of neuroinflammatory diseases among Korean children. A total of 13 children with neuroinflammatory diseases (8 males and 5 females; mean age 4.6 +/-2.6 yr) were consecutively recruited. Geno-mic typing was performed on their HLA DRB/HLA DQB genes using PCR-SSOP/SSP techniques with gel immunoelectrophoresis. The frequencies of HLA-DR1 *15 in children with acute disseminated encephalomyelitis (ADEM) (31%) and DQB1 *06 in other neuroinflammatory diseases (38%) were significantly increased compared with control subjects. The frequencies of HLA-DRB3 * 0202 (100%), HLA-DRB1 * 1302 (67%), HLA-DRB3 * 0301 (67%), and HLA-DQB1 * 0301 (67%) were significantly increased in children with multiple sclerosis and the frequencies of HLA-DRB1 * 1501 (40%) and HLA-DRB5 * 0101 (40%) were significantly increased in children with ADEM. HLA-DRB1 * 1401, HLA- DRB3 * 0202, and HLA-DQB1 * 0502 were found in children with acute necrotizing encephalopathy. In conclusion, HLA-DR1 * 15 and DQB1 * 06 may be involved in susceptibility to inflammation in Korean children. The frequencies of HLA-DRB1 * 1501, HLA-DRB5 * 0101, HLA-DRB3 * 0301, and HLA-DQB1* 0602 were not as high in Korean children with multiple sclerosis as in western children. However, HLA-DRB3 * 0202 was seen in all children with multiple sclerosis. Our data may provide further evidence that the immunogenetic background of neuroinflammatory diseases in Korean is distinctly different from the ones in western countries. Further studies are necessary to confirm this finding.

Platelet-activating factor acetylhydrolase gene polymorphism and its activity in Japanese patients with multiple sclerosis

We evaluated the association of the plasma platelet-activating factor acetylhydrolase (PAF-AH) gene polymorphism (G(994)-->T) and PAF-AH activity with susceptibility and severity of multiple sclerosis (MS) in Japanese. DNA was collected from 216 patients with clinically definite MS (65 opticospinal MS (OS-MS) and 151 conventional MS (C-MS)) and from 213 healthy controls. The missense mutation G(994)-->T that disrupts the PAF-AH activity was determined by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). No statistically significant difference in the frequency of genotypes and alleles of the plasma PAF-AH polymorphism was observed among OS-MS patients, C-MS patients and healthy controls. However, the missense mutation tended to be associated with the severity of OS-MS, especially in females (GT/TT genotypes; 51.7% in female rapidly progressive OS-MS vs. 26.6% in female controls, p=0.0870). Moreover, PAF-AH activities were significantly lower in MS than in controls, irrespective of clinical subtypes, among those carrying the identical polymorphism in terms of nucleotide position 994 of the PAF-AH gene. These findings suggest that the PAF-AH gene missense mutation has no relation to either susceptibility or severity of C-MS, yet its activity is down-regulated, and that the mutation has no relation with susceptibility of OS-MS, yet it may confer the severity of female OS-MS.

Tumor necrosis factor-alpha gene polymorphism at position -308 and schizophrenia in the Korean population

The purpose of the present study was to examine the association between the tumor necrosis factor (TNF)-alpha gene (A) polymorphism and schizophrenia in a Korean sample of schizophrenic patients and control subjects. Genotyping for the TNFA polymorphism was performed by polymerase chain reaction-restriction fragment length polymorphism. Genotype and allele distributions of the TNFA polymorphism between schizophrenic patients and controls were not significantly different. In the light of these results, the TNFA polymorphism seems not to confer susceptibility to the pathogenesis of schizophrenia, at least in the Korean population.

Multiple sclerosis in the Japanese population

Multiple sclerosis (MS) in Asian populations is characterised by the selective and severe involvement of the optic nerve and spinal cord as well as low prevalence rates. 15-40% of cases of MS in Japan are of this "opticospinal" type. This form of MS generally has a higher age at onset and a higher female to male ratio than conventional MS. Opticospinal MS is also characterised by frequent relapses, severe disability, few brain lesions visible on MRI, long lesions extending over many vertebral segments visible on spinal-cord MRI, pleocytosis and an absence of oligoclonal bands in the CSF, and a pronounced shift in the responses of T-helper-1 and T-cytotoxic-1 cells throughout relapse and remission phases. Conventional MS in Japanese people is, like MS in white people, associated with HLA-DRB1*1501, whereas opticospinal MS is associated with HLA-DPB1*0501. In Japanese people born after modernisation in the 1960s, the ratio of conventional to opticospinal MS has increased rapidly. Opticospinal MS is likely to have a distinct immune-mediated mechanism, which is not operative in conventional MS.

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.

Genetic analysis of multiple sclerosis

The increased recurrence risk within families indicates a role for genetic factors in the etiology of multiple sclerosis. Genes may influence susceptibility to the development of multiple sclerosis and the subsequent course of the disease. To date, associations have only been demonstrated consistently with class II major histocompatibility complex (MHC) alleles. The relatively low yield from additional candidate gene studies is only modestly advanced by several whole-genome linkage analyses, and by the first in a series of planned whole-genome linkage disequilibrium screens for allelic associations. The aims of linkage and association are to narrow the search for chromosomal regions encoding genes for multiple sclerosis and, with information from the human gene project, suggest new positional candidates. In time, it is expected that these genes will include some that confer susceptibility to the general process of autoimmunity, others that are specific for multiple sclerosis in all populations, some that act only in defined ethic groups, and those that determine particular phenotypes or shape the clinical course. These genetic analyses are predicated on the assumption that multiple sclerosis is one disease; a major part of future studies will be to resolve the question of disease heterogeneity in multiple sclerosis. When eventually in place, the potential of this genetic knowledge for improved understanding of the pathogenesis of multiple sclerosis and designing novel treatments is considerable.

Tumor necrosis factor microsatellite alleles in patients with rheumatoid arthritis in Taiwan

OBJECTIVE

To investigate the association of tumor necrosis factor (TNF) microsatellite alleles with the pathogenesis of rheumatoid arthritis (RA) in Taiwan.

METHODS

The TNF a, b, c, d, and e microsatellites were determined in 112 patients with RA and 99 healthy controls by using polymerase chain reaction (PCR) and electrophoresis with sequencing gel. All of these patients and controls had known HLA-DR genotypes and TNF-308 polymorphisms.

RESULTS

The phenotypic frequency of TNFa9 was significantly higher in DR4(-) RA patients than in DR4(-) controls. However, the phenotypic frequency of TNFb6 was significantly higher in RA patients than in controls in the presence of HLA-DR4. The phenotypic frequency of TNFa3-e1 was significantly lower in DR4(+) RA patients than in DR4(+) controls, while a negative linkage disequilibrium was noted between TNFa3-e1 and HLA-DR4. TNF microsatellite alleles were not related to the prevalences of bone erosion, rheumatoid nodule, sicca syndrome, pulmonary fibrosis, and seropositivity of rheumatoid factor (RF) in patients with RA.

CONCLUSION

The associations of TNF microsatellites with the susceptibility to RA in Taiwan are not completely independent of the HLA-DR associations. The association of TNFb6 with the susceptibility to RA depends on the presence of HLA-DR4, and the correlation of TNFa9 to RA depends on the absence of HLA-DR4. The negative association of TNFa3-e1 with RA may be secondary to the negative linkage disequilibrium between TNFa3-e1 and HLA-DR4. Moreover, TNFb6 and HLA-DR4 have a synergistic effect on the susceptibility to RA. TNFa3-e1 and TNF-308A have a synergistic effect on preventing from RA. The TNF microsatellite alleles are not related to the clinical manifestations and severity of RA patients in Taiwan.

Tumor necrosis factor, tumor necrosis factor receptors type 1 and 2, lymphotoxin-alpha, and HLA-DRB1 gene polymorphisms in human T-cell lymphotropic virus type I associated myelopathy

We studied tumor necrosis factor (TNF), lymphotoxin-alpha (LT-alpha), and TNF receptors type 1 (TNFR-1) and type 2 (TNFR-2) gene polymorphisms as well as HLA class II DRB1 alleles in Japanese patients with human T-cell lymphotropic virus type I (HTLV-I) associated myelopathy (HAM) (n = 51), patients with adult T-cell leukemia/lymphoma (ATL) (n = 48), asymptomatic HTLV-I carriers (n = 50), and HTLV-I seronegative, normal controls (n = 112). There were significant differences between HAM patients and normal controls in the distributions of TNF promoter region polymophism at position --857, the LT-alpha gene NcoI polymorphism, and the T-G substitution in exon 6 of the TNFR-2 gene. The distribution of the NcoI polymorphism of the LT-alpha gene was also significantly different between HAM patients and asymptomatic HTLV-I carriers. In contrast, we failed to detect any difference in the frequency of DRB1, TNF promoter at position --1031, --863, or the TNFR-1 promoter --383 polymorphism. The results suggest that the TNF/LT-alpha gene region within the HLA class III of chromosome 6 and the TNFR-2 gene region located on chromosome 1p36 might contribute to susceptibility to HAM, and that aberrant expression or function of these cytokines and the receptor could be involved in the development of HAM.

Flow cytometric differentiation of Asian and Western types of multiple sclerosis, HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP) and hyperIgEaemic myelitis by analyses of memory CD4 positive T cell subsets and NK cell subsets

We examined the alterations of memory CD4(+) T cell subsets bearing surface receptors linked to either Th1 or Th2 cytokine production as well as natural killer (NK) cell subsets by three color flow cytometry in the peripheral blood from 36 patients with clinically definite multiple sclerosis (MS), 27 patients with HAM/TSP, 13 patients with hyperIgEaemic myelitis who had mite antigen-specific IgE and 25 healthy controls (HC). The patients with MS were clinically classified into an optico-spinal form of MS (Asian type, MS-A) and the conventional form of MS (Western type, MS-W). MS-A showed a significant increase of CD4(+)CD45RA(-)CCR5(+) cells (Th1 cells) through the relapse and remission phases in comparison to HC, while MS-W showed a significant increase of CD4(+)CD45RO(+)CD62L(-) cells (Th1 cells) only at the relapse phase. HAM/TSP showed a significant increase of CCR5(+) and CD62L(-) memory CD4(+) T cells as well as CD30(+) memory CD4(+) T cells (Th2 cells) in comparison to HC. On the other hand, a selective increase of CD4(+)CD45RO(+)CD30(+) cells was found in hyperIgEaemic myelitis. The percentage of mature NK cells (CD3(-)CD16(+)CD56(+) cells) as well as double negative T cells (CD3(+)CD4(-)CD8(-) cells) decreased significantly in HAM/TSP in comparison to HC. Our findings therefore suggest a flow cytometric analysis of Th1/Th2-associated markers on memory CD4(+) T cells as well as NK cell subsets to be useful for differentiating various inflammatory neurologic conditions.

Susceptibility to multiple sclerosis: interplay between genes and environment

Multiple sclerosis is a complex trait of unknown etiology. Epidemiological data have shown that susceptibility to multiple sclerosis is determined by both genetic and environmental factors. It is unknown whether the clinical subcategories of multiple sclerosis are separate diseases with separate etiologies and causes. Recent theories of the pathogenesis of multiple sclerosis and candidate genes are discussed. Other potential nonchromosomal factors involved in multiple sclerosis susceptibility such as mitochondrial DNA and viral factors such as Chlamydia pneumoniae are reviewed.

Both the HLA-CPB1 and -DRB1 alleles correlate with risk for multiple sclerosis in Japanese: clinical phenotypes and gender as important factors

The purpose of this study was to clarify the association of HLA-DRB1 and -DPB1 alleles with multiple sclerosis (MS) in Japanese, to determine whether optico-spinal MS (OS-MS) and conventional MS are immunogenetically distinct, and to verify the role of gender difference in HLA associations of MS. We studied HLA-DRB1 and -DPB1 polymorphisms in 166 Japanese patients with MS. Forty-seven patients were classified as having the optico-spinal MS (OS-MS) and 119 as having conventional MS. A lack of DPB1*0301 and a higher frequency of DPB1*0501 compared with controls (corrected P<0.0074; odds ratio=9.48) were found in OS-MS. By contrast, we found for the first time an association of DPB1*0301 with conventional MS in Japanese (corrected P=0.0444; odds ratio=3.28). Logistic analysis, adjusted for sex and age, revealed independent associations of DPB1*0301 (P=0.0004, adjusted odds ratio (aOR)=4.70), DPB1*0501 (P=0.0081, aOR= 2.50) and DRB1*1501 (P=0.0252, aOR=2.21) with conventional MS. However, the frequencies of DRB1*1501 and DPB1*0501 in male patients with conventional MS were equal to those in male controls while the DPB1*0301 frequency was increased in both male and female patients. We did not find any association of these HLA alleles with disease course and severity. In conclusion, OS-MS is a DPB1*0501-associated distinct subtype of MS, and DPB1*0301 is the most strongly associated allele with conventional MS in Japanese. In addition, gender plays an important role in HLA association with MS.

DQB1*0602 confers genetic susceptibility to multiple sclerosis in Afro-Brazilians

We studied the distribution of the HLA-DRB1, -DQA1 and -DQB1 alleles in 44 Afro-Brazilian patients with multiple sclerosis and 88 controls. Although no significant differences were found between the patients and controls for the DRB1 and DQA1 alleles, the HLA-DQB1*0602 allele was positively associated with multiple sclerosis (45.0% vs. 17.0%, Pc=0.024, RR=3.31). The positive extended haplotypes for DQB1*0602 were more frequent in patients than controls, although the differences were not statistically significant in any of them. These results in Afro-Brazilians are in line with other studies which have found DQB1*0602 to be associated with the disease in the absence of the DRB1*1501 allele. We therefore think that the association with the disease in this ethnic group is more allelic than haplotypic.