A genomic screen of Spanish multiple sclerosis patients reveals multiple loci associated with the disease

A linkage study in two families with multiple sclerosis and healthy members with oligoclonal CSF immunopathy

We studied two extended families in which not only multiple sclerosis (MS) segregates, but also approximately 18% of the cerebrospinal fluid (CSF) investigated blood relatives have ‘MS immunopathic trait’, an oligoclonal CSF immunopathy similar to that seen in MS, but with no neurological symptoms. Both families fit a genetic model for autosomal dominant inheritance for MS immunopathic trait, although with reduced penetrance in family A. In order to identify genetic factors of importance for the development of MS immunopathic trait, we performed a genome scan using the CHLC/Weber Screening Set (ver 6A), with 285 successful markers, to test the hypothesis that a single gene is causing the MS immunopathic trait in these families. Using a parametric method, we identified regions with suggestive linkage at chromosome 6q12 with a LOD-score of 2.4, putative linkage with LOD-score 1.5 at chromosome 6p21 (HLA region), putative linkage at chromosome 12q24 with a LOD-score of 1.7 and suggestive linkage at chromosome 19q13.2 with a LOD-score of 1.8. The LOD-score at chromosome 19q13.2 increased to 2.2 when only family A was analysed. In family A, all MS patients and two of five individuals with MS immunopathic trait had HLA DRB1*(15) and in family B, all blood relatives had the rare HLA type DRB1*0103, which is associated with other autoimmune diseases. We suggest that DRB1*0103 is a necessary but not sufficient condition for the susceptibility for MS immunopathic trait in this family.

Genome-wide association study of IgA nephropathy using 23 465 microsatellite markers in a Japanese population

Immunoglobulin A nephropathy (IgAN) is the most common form of primary glomerulonephritis in many parts of the world. Although previous genome-wide association studies (GWAS) identified the major susceptibility loci for IgAN, the causal genes currently remain unknown. We performed a GWAS using 23 465 microsatellite (MS) markers to identify genes related to IgAN in a Japanese population. A pooled sample analysis was conducted in three-stage screenings of three independent case-control populations, and after the final step of individual typing, 11 markers survived. Of these, we focused on two regions on 6p21 and 12q21 because they (i) showed the strongest relationship with IgAN, and (ii) appeared to be highly relevant to IgAN in view of several previous studies. These regions contained the HLA, TSPAN8 and PTPRR genes. This study on GWAS, using >20 000 MS markers, provides a new approach regarding susceptible genes for IgAN for investigators seeking new tools for the prevention and treatment of IgAN.

Tumor necrosis factor-alpha polymorphism and susceptibility to multiple sclerosis in the Iranian population

BACKGROUND

Multiple sclerosis (MS) is an immune-mediated disease of polygenic etiology. Tumor necrosis factor-α (TNF-α) microsatellite as a proinflammatory cytokine is believed to play an important role in the etiology of this disease.

OBJECTIVES

The aim of this study was to investigate the association of TNF-α microsatellite sequence variation in patients with MS and its risk factor in the southern Iranian population.

PATIENTS AND METHODS

This polymorphism was investigated in an Iranian population of 163 native southern people [81 patients with MS according to the poser criteria and 82 healthy controls (HC) with the same age, sex, social, ethnical and geographical features (Hormozgan and Fars provinces)]. All the controls were nonimmunological, neurological patients. All the cases and controls were chosen randomly and genotyped for polymorphism of TNF-α microsatellite.

RESULTS

The frequencies of TNF-α*11 (0.25, P < 0.005) and TNF-α*10 (P < 0.005) alleles increased in patients with MS compared with controls, showing a significant difference among the studied population.

CONCLUSIONS

The current study adds evidence to the association of TNF-α gene polymorphism and MS in this southern south Iranian population which is consistent with the genetic analysis of MS in Europeans (GAMES) project reports and these two alleles reported in this study may be one of the genetic risk factor for MS. Furthermore, this data can be used to build the Iranian gene bank for future studies.

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.

Genetic determinants of neuronal vulnerability to apoptosis

Apoptosis is a common mode of cell death that contributes to neuronal loss associated with neurodegeneration. Single-nucleotide polymorphisms (SNPs) in chromosomal DNA are contributing factors dictating natural susceptibility of humans to disease. Here, the most common SNPs affecting neuronal vulnerability to apoptosis are reviewed in the context of neurological disorders. Polymorphic variants in genes encoding apoptotic proteins, either from the extrinsic (FAS, TNF-α, CASP8) or the intrinsic (BAX, BCL2, CASP3, CASP9) pathways could be highly valuable in the diagnosis of neurodegenerative diseases and stroke. Interestingly, the Arg72Pro SNP in TP53, the gene encoding tumor suppressor p53, was recently revealed a biomarker of poor prognosis in stroke due to its ability to modulate neuronal apoptotic death. Search for new SNPs responsible for genetic variability to apoptosis will ensure the implementation of novel diagnostic and prognostic tools, as well as therapeutic strategies against neurological diseases.

CD24 gene allele variation is not associated with oligoclonal IgG bands and IgG index of multiple sclerosis patients

OBJECTIVE

Multiple sclerosis (MS) shows evidence of many distinctive aspects of an autoimmune disorder, including a polygenic inheritance. A recent candidate gene for susceptibility to MS is CD24, which has also been shown to be associated with disease progression. This study was designed to examine whether there is a relationship between the CD24 genotype, oligoclonal band (OCB) status and IgG index in the cerebrospinal fluid (CSF) of MS patients.

METHODS

A total of 27 definite MS patients were enrolled in this cross-sectional study. Blood samples were collected from a peripheral vein, and CSF was obtained by lumbar puncture. The CD24 gene was sequenced in the blood specimen, and albumin and IgG concentrations were measured in both CSF and serum. We compared both IgG index and OCB status in patients with and without CD24V/V. The correlation between MS severity score (MSSS), OCB status, CD24 genotype and IgG index was studied.

RESULTS

Only 15 patients were OCB positive. Among patients with negative OCBs, only 2 patients had the V/V genotype. Furthermore, in those with the V/V genotype, IgG index was not significantly elevated (p = 0.322). Patients with the V/V genotype had a significantly higher MSSS (p = 0. 04), but neither the presence of OCBs nor the IgG index showed significant correlation with MSSS (p = 0.379 and 0.20, respectively).

CONCLUSION

We could not show any relationship between the CD24V/V genotype, OCB status and IgG index. This could be interpreted as indicating that the CD24V/V allele exerts its effects on the disease course independently of CSF IgG synthesis.

Influence of neurosteroids on the pathogenesis of multiple sclerosis

This paper summarizes neuroendocrine effects on myelination and their possible relevance for the pathogenesis of multiple sclerosis (MS). Steroid hormones known as neurosteroids are synthesized in the human central nervous system (CNS) and exert local effects on glial and neuronal tissue. Progesterone derivatives seem to act as promyelinating factors in the slow but continuous process of myelin maintenance in the adult human brain. Diminished production of these myelin-promoting factors may lead to the formation of structurally altered and less stable myelin, resulting in the observed pathology of the normal-appearing white matter (NAWM) in MS. Dysmyelination, characterized by an altered myelin protein composition, reduced myelin content and increased vulnerability of the myelin sheath, precedes the formation of inflammatory lesions and the clinical onset of disease. Defects in the myelin sheath first occur in mechanically strained areas of the brain, where myelin turnover is physiologically increased. The continuous exposure of myelin proteins, normally sheltered from immunosurveillance, will lead to microglia activation and phagocytosis of myelin. Phagocytic cells from the brain and myelin material may drain to cervical lymph nodes with subsequent priming of T-cells. Finally, heterogenous focal auto-inflammatory reactions contribute to the clinical symptoms of the disease. Neurosteroids influence the biochemical composition of myelin proteins and promote myelin renewal. These promyelinating neurosteroidal functions seem to be impaired in the MS brain. Contrary to the view of auto-inflammatory demyelination being a causative factor in MS pathogenesis, it is argued here that widespread dysmyelination in the adult human brain precedes and induces a focal immune response to various myelin compounds.

Association between synapsin III gene promoter SNPs and multiple sclerosis in Basque patients

BACKGROUND

Synapsins are a family of neuron-specific phosphoproteins, one of whose subunits is encoded by the SYN3 gene. This gene is located close to one of the multiple sclerosis susceptibility regions (in 22q13.1). Two single-nucleotide polymorphisms (SNPs) (rs133945 and rs133946) in the promoter region of this gene have been proposed as factors protecting against MS. This relationship is not clear because another report failed to found such association.

OBJECTIVES

In an attempt to clarify this association, the frequency of these SNPs was analyzed in a population of 221 Spanish MS patients with a cluster of 72 Basque patients and in 373 controls with a cluster of 138 controls of a Basque origin.

METHODS

The SNis analysis was performed by 9 PCR.

RESULTS

According to our findings, these SNPs are differently distributed in the two populations. This significant bias should therefore be taken into account in association studies. Our data suggest that the C/C genotype in rs133946 and the G/G genotype in rs133945 could be protecting factors against MS in the Basque population.

Variations of the perforin gene in patients with multiple sclerosis

Perforin is involved in cell-mediated cytotoxicity and mutations of its gene (PRF1) cause familial hemophagocytic lymphohistiocytosis (FLH2). PRF1 sequencing in 190 patients with multiple sclerosis and 268 controls detected two FLH2-associated variations (A91V, N252S) in both groups and six novel mutations (C999T, G1065A, G1428A, A1620G, G719A, C1069T) in patients. All together, carriers of these variations were more frequent in patients than in controls (phenotype frequency: 17 vs 9%, P=0.0166; odds ratio (OR)=2.06, 95% confidence interval (CI): 1.13-3.77). Although A91V was the most frequent variation and displayed a trend of association with multiple sclerosis (MS) in the first population of patients and controls (frequency of the 91V allele: 0.076 vs 0.043, P=0.044), we used it as a marker to confirm PRF1 involvement in MS and assessed its frequency in a second population of 966 patients and 1520 controls. Frequency of the 91V allele was significantly higher in patients than in controls also in the second population (0.075 vs 0.058%, P=0.019). In the combined cohorts of 1156 patients and 1788 controls, presence of the 91V allele in single or double dose conferred an OR=1.38 (95% CI=1.10-1.74). These data suggest that A91V and possibly other perforin variations indicate susceptibility to MS.

Evidence for association of chromosome 10 open reading frame (C10orf27) gene polymorphisms and multiple sclerosis

A recent association study has provided evidence that chromosome 10q22.1 may contain candidate genes for multiple sclerosis (MS). We analysed two intronic and a non-synonymous single nucleotide polymorphism (SNP) of the C10orf27 gene in 571 patients with MS (relapsing remitting and primary progressive) and healthy controls. Adjusted comparisons revealed significant association with disease susceptibility for one intronic SNP in RRMS individuals and the amino acid modifying SNP for PPMS cases; the latter may also contribute to faster disease progression. Transcript expression in brain lesions from MS patients was increased. These findings suggest C10orf27 as a candidate gene for MS susceptibility and pathogenesis. Multiple selerosis 2008; 14: 412—414. http://msj.sagepub.com

Multiple sclerosis genetics

Multiple sclerosis (MS) clusters with the so-called complex genetic diseases, a group of common disorders characterized by modest disease risk heritability and multifaceted gene-environment interactions. The major histocompatibility complex (MHC) is the only genomic region consistently associated with MS, and susceptible MHC haplotypes have been identified. Although the MHC does not account for all genetic contribution to MS, the other genetic contributors have been elusive. Microarray gene-expression studies, which also have not identified a major MS locus, have, however, been promising in elucidating some of the possible pathways involved in the disease. Yet, microarray studies thus far have been unable to separate the genetic causes of MS from the expression consequences of MS. The use of new methodologies and technologies to refine the phenotype, such as brain spectroscopy, PET and functional magnetic resonance imaging combined with novel computational tools and a better understanding of the human genome architecture, may help resolve the genetic causes of MS.

Multiple sclerosis susceptibility and the X chromosome

Multiple sclerosis (MS) is a chronic autoimmune complex trait with strong evidence for a genetic component. A female gender bias is clear but unexplained and a maternal parent-of-origin effect has been described. X-linked transmission of susceptibility has been previously proposed, based on pedigree, association and linkage studies. We genotyped 726 relative pairs including 552 affected sib-pairs for 22 X-chromosome microsatellite markers and a novel dataset of 195 aunt-uncle/niece-nephew (AUNN) affected pairs for 18 markers. Parent-of-origin effects were explored by dividing AUNN families into likely maternal and paternal trait transmission. For the sib-pair dataset we were able to establish exclusion at a lambda s = 1.9 for all markers using an exclusion threshold of LOD < or = -2. Similarly for the AUNN dataset, we established exclusion at lambdaAV = 1.9. For the combined dataset we estimate exclusion of lambda = 1.6. We did not identify significant linkage in either the sib-pairs or the AUNN dataset nor when datasets were stratified for the presence/absence of the HLA-DRB1*15 allele or for paternal or maternal transmission. This comprehensive scrutiny of the X-chromosome suggests that it is unlikely to harbour an independent susceptibility locus or one which interacts with the HLA. Complex interactions including epigenetic ones, and masking by balanced polymorphisms are mechanisms not excluded by the approach taken.

Influence of CCR5-Δ32 genotype in Spanish population with multiple sclerosis

A number of association studies have explored the relationship between the CCR5-Delta32 allele and the risk of developing multiple sclerosis (MS), with varying results. In light of the results of several studies that have analyzed the role of the allele in MS, it has been proposed that the allele is involved in the etiopathogeny of the disease. Our study revealed a statistically significant difference between the study group and the control group for the carriers of at least one deleted allele (P = 0.027). The allele was more frequent in the control group, which suggests a possible protective effect of this deletion against MS. When ethnic origin was taken into account in the same analysis, we saw that the bulk of the difference was attributable to the Basque group, although the trend was also visible in the control group. Consideration of ethnic origin is therefore essential for the analysis of our sample. CCR5-Delta32 allele distribution was higher in the Basque control population than in the Basque MS population, which suggests that it confers a protective effect against MS. Relevant values were a P value of 0.008 and an odds ratio of 0.168 (95% confidence interval, 0.038 to 0.737).

CD24 V/V is an allele associated with the risk of developing multiple sclerosis in the Spanish population

The allele C in the CD24 gene has been related to multiple sclerosis (MS). In this work we check this single nucleotide polymorphism (SNP) in a population of 135 patients and 285 controls. Our results confirm the association between the V/V genotype at aa 57 of this gene and MS and highlight the importance of taking into account the origin of the subjects to avoid a population bias.

Linkage disequilibrium screening for multiple sclerosis implicates JAG1 and POU2AF1 as susceptibility genes in Europeans

By combining all the data available from the Genetic Analysis of Multiple sclerosis in EuropeanS (GAMES) project, we have been able to identify 17 microsatellite markers showing consistent evidence for apparent association. As might be expected five of these markers map within the Major Histocompatibility Complex (MHC) and are in LD with HLA-DRB1. Individual genotyping of the 12 non-MHC markers confirmed association for three of them--D11S1986, D19S552 and D20S894. Association mapping across the candidate genes implicated by these markers in 937 UK trio families revealed modestly associated haplotypes in JAG1 (p=0.019) on chromosome 20p12.2 and POU2AF1 (p=0.003) on chromosome 11q23.1.

Genetic investigation of methylenetetrahydrofolate reductase (MTHFR) and catechol-O-methyl transferase (COMT) in multiple sclerosis

Multiple sclerosis (MS) is a chronic neurological disease characterized by central nervous system (CNS) inflammation and demyelination. The C677T substitution variant in the methylenetetrahydrofolate reductase (MTHFR) gene has been associated with increased levels of circulating homocysteine and is a mild risk factor for vascular disease. Higher blood levels of homocysteine have also been reported in MS. Thus, the C677T mutation of the MTHFR gene may influence MS susceptibility. Noradrenaline, a neurotransmitter believed to play an immunosupressive role in neuroinflammatory disorders, is catabolized by catechol-O-methyl transferase (COMT). The COMT G158A substitution results in a three- to four-fold decreased activity of the COMT enzyme, which may influence CNS synaptic catecholamine breakdown and could also play a role in MS inflammation. We tested DNA from Australian MS patients and unaffected control subjects, matched for gender, age and ethnicity. Specifically, we genotyped the MTHFR C677T and the COMT G158A mutations. Genotype distributions showed that the homozygous mutant MTHFR genotype (T/T) and the COMT (H/H) genotype were slightly over-represented in the MS group (16% versus 11% and 24% versus 19%, respectively), but both variations failed to reach statistical significance (P=0.15 and P=0.32, respectively). Hence, results from the present study do not support a major role for either functional gene mutation in MS susceptibility.

Mapping gene activity in complex disorders: Integration of expression and genomic scans for multiple sclerosis

Genetic predisposition contributes to the pathogenesis of most common diseases. Genetic studies have been extremely successful in the identification of genes responsible for a number of Mendelian disorders. However, with a few exceptions, genes predisposing to diseases with complex inheritance remain unknown despite multiple efforts. In this article we collected detailed information for all genome-wide genetic screens performed to date in multiple sclerosis (MS) and in its animal model experimental autoimmune encephalomyelitis (EAE), and integrated these results with those from all high throughput gene expression studies in humans and mice. We analyzed a total of 55 studies. We found that differentially expressed genes (DEG) are not uniformly distributed in the genome, but rather appear in clusters. Furthermore, these clusters significantly differ from the known heterogeneous organization characteristic of eukaryotic gene distributions. We also identified regions of susceptibility that overlapped with clusters of DEG leading to the prioritization of candidate genes. Integration of genomic and transcriptional information is a powerful tool to dissect genetic susceptibility in complex multifactorial disorders like MS.

HLA genomics in the third millennium

The MHC region contains several unique characteristics that set it apart as the most important region in the vertebrate genome in relation to disease. Recent data fit with the long-held view that the polymorphism of this region is driven by resistance to infection, although this is not yet proven. Interestingly, the MHC gene complex is associated with most, if not all, of the common autoimmune conditions. It has been difficult to identify the precise MHC genes associated with infection and autoimmunity, mainly because of the strong linkage disequilibrium over the region. Over the past few years, tools have been developed in an attempt to overcome these problems, including multiple fully sequenced MHC haplotypes, which have led to high-density hapmaps. In conjunction with large well-documented patient/control groups and sophisticated statistical methods these advances are starting to provide a comprehensive view of the genetics of the HLA region and disease susceptibility.

Variation in the vitamin D receptor gene is associated with multiple sclerosis in an Australian population

Multiple Sclerosis (MS) is a chronic inflammatory demyelinating disease of the central nervous system (CNS) resulting in accumulating neurological disability. The disorder is more prevalent at higher latitudes. To investigate VDR gene variation using three intragenic restriction fragment length polymorphisms (Apa I, Taq I and Fok I) in an Australian MS case-control population. One hundred and four Australian MS patients were studied with patients classified clinically as Relapsing Remitting MS (RR-MS), Secondary Progressive MS (SP-MS) or Primary Progressive MS (PP-MS). Also, 104 age-, sex-, and ethnicity-matched controls were investigated as a comparative group. Our results show a significant difference of genotype distribution frequency between the case and control groups for the functional exon 9 VDR marker Taq I (p(Gen) = 0.016) and interestingly, a stronger difference for the allelic frequency (p(All) = 0.0072). The Apa I alleles were also found to be associated with MS (p(All) = 0.04) but genotype frequencies were not significantly different from controls (p(Gen) = 0.1). The Taq and Apa variants are in very strong and significant linkage disequilibrium (D' = 0.96, P < 0.0001). The genotypic associations are strongest for the progressive forms of MS (SP-MS and PP-MS). Our results support a role for the VDR gene increasing the risk of developing multiple sclerosis, particularly the progressive clinical subtypes of MS.

Haplotypes within genes of beta-chemokines in 17q11 are associated with multiple sclerosis: a second phase study

We previously defined haplotypes of single nucleotide polymorphisms (SNP) with possible relevance to multiple sclerosis (MS) in 2 CC chemokine ligand (CCL) clusters in chromosome 17q11. The 17q11 region was also identified as a susceptibility locus by a meta-analysis of linkage studies. To confirm and refine the previous finding in a second, high resolution SNP scan in a new set of families. We genotyped 232 SNPs in 1369 individuals in 361 MS families. Transmission of marker alleles and haplotypes from unaffected parents to affected offspring was tested by using the pedigree disequilibrium test, the TRANSMIT 2.5 program, and the family and haplotype based association tests. Distribution of linkage disequilibrium (LD) was assessed by ldmax. In consensus with observations in the first scan, the present study identified haplotypes within CCL3 and CCL15 in the telomeric CCL cluster. There was also an overlap in the findings in the centromeric CCL cluster. Strong and extensive LD was detected both within the centromeric and telomeric CCL gene clusters. The present study replicates our previous findings and further suggests the existence of MS associated haplotypes within genes of CCL3 and CCL15. Haplotypes of interest are also present within the centromeric gene cluster (including CCL2, CCL7, CCL11, CCL8, and CCL13), but extensive LD prevents further refinement of these haplotypes by using the methods applied. Sequencing of the identified chromosomal segments and their flanking regions will be necessary to define specific variants with direct relevance to MS pathogenesis.

Genetic association between polymorphisms in the ADAMTS14 gene and multiple sclerosis

ADAMTS14 is a novel member of the ADAMTS (a disintegrin-like and metalloproteinase domain with thrombospondin type 1 modules) metalloproteinase family which processes extracellular matrix proteins. In the present study we performed a comprehensive investigation of the ADAMTS14 as a candidate gene for susceptibility to multiple sclerosis (MS). Eight single nucleotide polymorphisms (SNPs) were analyzed in a case-control study of 287 patients with MS [192 with relapsing-remitting MS (RRMS) and 95 with primary-progressive MS (PPMS)], and 285 age- and sex-matched controls. Allele and genotype frequencies were compared between controls and the MS subgroups, and gene-based haplotypes were reconstructed by computational procedures. Pairwise linkage disequilibrium values (D') suggested that three locus pairs (SNPs 3 through 5) had alleles in strong disequilibrium and constituted a haplotype block spanning 14 kb. Overall comparisons of allele and genotype frequencies showed association for SNPs 3 and 6 with MS. Stratification of MS patients according to major clinical forms revealed an increased frequency of both allele C (p = 0.006) and CC homozygosity (p = 0.008) at SNP6 in RRMS patients compared with controls. PPMS was associated with allele A at SNP2 compared with RRMS (p = 0.003) and controls (p = 0.009), and with CG heterozygosity at SNP3 compared with controls (p = 0.005). Haplotype frequency comparisons showed significant association between PPMS and the AGGGC haplotype compared with controls (p = 0.0004), and negative association between RRMS and the GGAGT haplotype compared with controls (p = 0.0026). No association was detected between different genotypes and disease severity measured by the Multiple Sclerosis Severity Score (MSSS). These findings suggest a potentially important role for the ADAMTS14 gene in predisposition to MS.

Mitochondrial haplogroups in Basque multiple sclerosis patients

Previous studies have suggested that mitochondrial metabolism and/or mitochondrial DNA (mtDNA) could be, in conjunction with other genetic or environmental factors, a risk factor for the development of multiple sclerosis (MS). One of these studies establishes that mitochondrial haplogroup JT is a risk factor for developing the disease, in particular the visual manifestations [optic neuritis (ON)]. Nevertheless, as distribution of these haplogroups varies between populations, the observed association may be due to a slanted sample with no physiopathological value. This hypothesis was checked with MS patients, originals from Basque country (this population has peculiar genetic characteristics) and from other Spanish regions. We concluded that such an association does not exist. By contrast, a decrease could be seen in the frequency of the JT haplogroup in the ON group and in the MS-Basque group. That trend could be a protective effect, which needs to be verified in further investigations.

Chromosome 17p12-q11 harbors susceptibility loci for systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is an autoimmune disease characterized by the presence of autoantibodies against intracellular components, the formation of immune complexes, and inflammation in various organs, typically the skin and kidney glomeruli. The etiology of the disease is not well understood but is most likely the result of the interaction between genetic and environmental factors. In order to identify susceptibility loci for SLE, we have performed genome scans with microsatellite markers covering the whole genome in families from Argentina, Italy, and Europe. The results reveal a heterogeneous disease with different susceptibility loci in different family sets. We have found significant linkage to chromosome 17p12-q11 in the Argentine set of families. The maximum LOD score was given by marker D17S1294 in combination with D17S1293, when assuming a dominant inheritance model (Z = 3.88). We also analyzed a repeat in the promoter region of the NOS2A gene, a strong candidate gene in the region, but no association was found. The locus on chromosome 17 has previously been identified in genetic studies of multiple sclerosis families. Several other interesting regions were found at 1p35, 1q31, 3q26, 5p15, 11q23 and 19q13, confirming previously identified loci for SLE or other autoimmune diseases.