A cytokine gene screen uncovers SOCS1 as genetic risk factor for multiple sclerosis.

Cytokine and cytokine receptor genes, including IL2RA, IL7R and IL12A, are known risk factors for multiple sclerosis (MS). Excitotoxic oligodendroglial death mediated by glutamate receptors contributes to demyelinating reactions. In the present study, we screened 368 single-nucleotide polymorphisms (SNPs) in 55 genes or gene clusters coding for cytokines, cytokine receptors, suppressors of cytokine signaling (SOCS), complement factors and glutamate receptors for association with MS in a Spanish-Basque resident population. Top-scoring SNPs were found within or nearby the genes coding for SOCS-1 (P=0.0005), interleukin-28 receptor, alpha chain (P=0.0008), oncostatin M receptor (P=0.002) and interleukin-22 receptor, alpha 2 (IL22RA2; P=0.003). The SOCS1 rs243324 variant was validated as risk factor for MS in a separate cohort of 3919 MS patients and 4003 controls (combined Cochran-Mantel-Haenszel P=0.00006; odds ratio (OR)=1.13; 95% confidence interval (CI)=1.07-1.20). In addition, the T allele of rs243324 was consistently increased in relapsing-remitting/secondary progressive versus primary-progressive MS patients, in each of the six data sets used in this study (P(CMH)=0.0096; OR=1.24; 95% CI 1.05-1.46). The association with SOCS1 appears independent from the chr16MS risk locus CLEC16A.

ANKRD55 and DHCR7 are novel multiple sclerosis risk loci.

Multiple sclerosis (MS) shares some risk genes with other disorders hallmarked by an autoimmune pathogenesis, most notably IL2RA and CLEC16A. We analyzed 10 single-nucleotide polymorphisms (SNPs) in nine risk genes, which recently emerged from a series of non-MS genome-wide association studies (GWAS), in a Spanish cohort comprising 2895 MS patients and 2942 controls. We identified two SNPs associated with MS. The first SNP, rs6859219, located in ANKRD55 (Chr5), was recently discovered in a meta-analysis of GWAS on rheumatoid arthritis (RA), and emerged from this study with genome-wide significance (odds ratio (OR) = 1.35; P = 2.3 × 10(-9)). The second SNP, rs12785878, is located near DHCR7 (Chr11), a genetic determinant of vitamin D insufficiency, and showed a size effect in MS similar to that recently observed in Type 1 diabetes (T1D; OR = 1.10; P = 0.009). ANKRD55 is a gene of unknown function, and is flanked proximally by the IL6ST-IL31RA gene cluster. However, rs6859219 did not show correlation with a series of haplotype-tagging SNPs covering IL6ST-IL31RA, analyzed in a subset of our dataset (D'< 0.31; r(2)< 0.011). Our results expand the number of risk genes shared between MS, RA and T1D.

Replication of top markers of a genome-wide association study in multiple sclerosis in Spain.

Multiple sclerosis (MS) is a chronic inflammatory disease of the central nervous system with presumed autoimmune origin, triggered by genetic and environmental risk factors. A recent genome-wide association study conducted on MS identified new biallelic markers outside the HLA (human leucocyte antigen) region involved in disease susceptibility: rs1109670 (DDEF2); rs1458175 (PDZRN4); rs1529316 and rs2049306 (CSMD1); rs16914086 (TBC1D2); rs1755289 (SH3GL2); rs1841770 (ZIC1); rs651477 (EN1); rs7607490 (TRIB2); rs397020 (C20orf46); rs908821 (SLC25A36); rs7672826 (MGC45800) and rs9523762 (GPC5). We aimed at replicating these top association signals in a Spanish cohort of 2863 MS patients and 2930 sex- and age-matched controls. Only rs9523762 mapping in the GPC5 gene was significantly associated (G allele, P=1.6 × 10(-5); odds ratio (95% confidence interval)=1.23 (1.12-1.36)), supporting a role for this proteoglycan in MS predisposition. The independent replication of association signals to validate data generated by genome-wide association scans is a first step in the effort to improve patient care.

The autoimmune disease-associated KIF5A, CD226 and SH2B3 gene variants confer susceptibility for multiple sclerosis.

Genome-wide association studies (GWAS) have revealed that different diseases share susceptibility variants. Twelve single-nucleotide polymorphisms (SNPs) previously associated with different immune-mediated diseases in GWAS were genotyped in a Caucasian Spanish population of 2864 multiple sclerosis (MS) patients and 2930 controls. Three SNPs were found to be associated with MS: rs1678542 in KIF5A (P=0.001, odds ratio (OR)=1.13, 95% confidence interval (CI)=1.05-1.23); rs3184504 in SH2B3 (P=0.00001, OR=1.19, 95% CI=1.10-1.27) and rs763361 in CD226 (P=0.00007, OR=1.16, 95%CI=1.08-1.25). These variants have previously been associated with rheumatoid arthritis and type 1 diabetes. The SH2B3 polymorphism has additionally been associated with systemic lupus erythematosus. Our results, in addition to validating some of these loci as risk factors for MS, are consistent with shared genetic mechanisms underlying different immune-mediated diseases. These data may help to shape the contribution of each pathway to different disorders.

Multiple sclerosis association study with the TENR-IL2-IL21 region in a Spanish population.

Polymorphisms from the TENR-IL2-IL21 block in the 4q27 chromosome were recently associated with type 1 diabetes, celiac disease, rheumatoid arthritis and psoriasis. We undertook this study to investigate the potential role of polymorphisms rs3136534, rs6822844 and rs2069762 (-330 T/G IL2) in multiple sclerosis (MS) (805 patients of Spanish Caucasian origin and 952 health controls). We did not find evidence for association with any single nucleotide polymorphisms (SNPs) tested. Allele and genotype frequencies of the SNPs, which were studied, were similar in DRB1*15-positive or DRB1*15-negative patients. After stratification of MS patients by clinical course, a weak association was observed with rs2069762 G allele and haplotype bearing this allele with secondary progressive MS, although these cases represent 22% of the MS cases. Our results did not show major influence of TENR-IL2-IL21 locus on susceptibility or disease progression in MS. However, we could not exclude completely the effect in MS for this region. Additional studies, using much larger sample sizes and analysis of additional polymorphisms in the gene and its flanking region, will be required to ascertain their contributions to MS susceptibility.

The T244I variant of the interleukin-7 receptor-alpha gene and multiple sclerosis.

Several but not all studies have provided evidence for the association between multiple sclerosis (MS) and the T244I variant of the interleukin-7 receptor-alpha gene (IL7RA), rs6897932. We performed a new replication case-control study in 599 MS patients and 594 healthy controls, all Caucasians from the south of Spain. The genotype and allele frequencies differed between MS cases and controls. The IL7RA rs6897932 C allele and the CC genotype were found to be factors for disease susceptibility [per allele odds ratio (OR) 1.32, 95% CI 1.1-1.6, P=0.0031; per CC genotype vs TT + TC genotypes, OR 1.5, 95% CI 1.18-1.87, P=0.0007]. The combined data analysis included 3324 cases and 5032 controls of Europeans and Americans of European origin resulting in stronger association with similar OR (P=1.9 x 10E-9). These findings in our sample support previous reported association studies between IL7RA rs6897932 and MS.

OAS1 gene haplotype confers susceptibility to multiple sclerosis.

Multiple sclerosis (MS) is associated with genetic susceptibility and unknown environmental triggers, possible viral infections, but the specific etiological mechanism that subsequently develops into an inflammatory/autoimmune cascade of events is poorly understood. Recently, genetic variants of 2',5'- oligoadenylate synthetase 1 (OAS1) gene, a critical enzyme involved in innate antivirus response, have been associated with differential enzyme activity and type 1 diabetes in both case-control and family studies. We hypothesized that polymorphisms in the OAS1 gene could influence the susceptibility to MS. To test this hypothesis, we conducted a case-control study of 333 patients with MS and 424 healthy controls and genotyped two OAS1 single nucleotide polymorphisms (SNPs) by restriction fragment length polymorphism method: rs 10774671, A/G SNP altering the splicing site at the seventh exon, and rs 3741981, a nonsynonymous (Ser162Gly) A/G SNP in the third exon. Haplotype but not single-marker analysis revealed an association of the haplotype created by the G allele at rs 10774671 and the A allele at rs 3741981 with the susceptibility to MS (P value = 8.8 x 10(-5)). Subjects carrying this haplotype had an increased risk of MS comparing with those not carrying it (odds ratio = 4.7, 95% confidence interval 2.1-10.9). Our findings indicate that the OAS1 gene polymorphisms may confer susceptibility to MS or serve as markers of functional variants and suggest that OAS1 activity is involved in the etiology of the disease. Future studies in a larger sample and association analysis with functional variants will clarify the role of the OAS1 gene in the susceptibility to MS.

The 1858T PTPN22 gene variant contributes to a genetic risk of type 1 diabetes in a Ukrainian population.

The 1858T variant of the protein tyrosine phosphatase gene, PTPN22, is associated with an increased risk of several autoimmune diseases. The aim of this study has been to investigate the possible association of 1858C-->T PTPN22 polymorphism and type 1 diabetes (T1D) in Caucasians from Ukraine. Overall, the distribution of 1858 PTPN22 genotypes differed significantly between the T1D patient group (n = 296) and the control group (n = 242) (P = 0.0036). When both groups were classified according to sex, the TT genotype and T allele showed a statistically significant higher frequency in T1D female patients (5.9 and 22.8%, respectively) in comparison with the female controls (0 and 11.9%) (P = 0.008 for both analyses). The patients with the TT genotype were significantly younger at the onset of T1D compared with those with genotypes TC and CC (P = 0.035 and 0.019, respectively). In our Ukrainian Caucasian cohort, we confirmed the association between T1D and the PTPN22,1858T allele.

Analysis of -631 and -475 interleukin-2 promoter single nucleotide polymorphisms in multiple sclerosis.

We have analysed the interleukin-2 (IL-2) promoter single nucleotide polymorphisms -475 A/T and -631 G/A, relative to the initiation codon, in patients with multiple sclerosis (MS) and in healthy controls. Both groups showed a very low frequency of T at -475 and A at -631. Our results suggest that these polymorphisms do not contribute to MS susceptibility.

The -174/-597 promoter polymorphisms in the interleukin-6 gene are not associated with susceptibility to multiple sclerosis.

Interleukin-6 (IL-6) has been implicated in the etiology of experimental autoimmune encephalomyelitis (EAE) in transgenic animals and contributes to neuropathology in humans. A single nucleotide polymorphism (SNP) at position -174 in the IL-6 gene promoter (IL-6pr) appears to influence IL-6 expression. Complete linkage disequilibrium was observed between the -174 and the -597 alleles. The aim of this study was to investigate the possible influence of -174/-597 IL-6pr polymorphisms on susceptibility to multiple sclerosis (MS). Genotyping of the -597 variant was performed by an RFLP method in 131 MS patients [88 relapsing-remitting (RR-MS), 43 secondary progressive (SP-MS)] and 157 healthy subjects. No differences were found between MS patients and controls with respect to the distribution of -597 IL-6pr genotypes. Neither was found when genotypes were analyzed according to the clinical course of the disease (RR-MS or SP-MS). Future studies focusing on complex transcriptional interactions between the IL-6pr and 3' flanking region polymorphic sites will be necessary to determine the IL-6 haplotype influence on susceptibility to MS.

Allelic expression and interleukin-2 polymorphisms in multiple sclerosis.

We have investigated the association of two single nucleotide polymorphisms (SNPs) at positions -384 and 114 in the human interleukin-2 (hIL-2) with multiple sclerosis (MS). For two of the -384 genotypes (G/T, T/T), we observed an association with the susceptibility to secondary progressive (SP) course of MS (P=0.005 and P=0.013, respectively). Expression level differences of the IL-2 alleles (between one- and three-fold) were not attributable to the -384 promoter polymorphism. These data indicate for the first time the relevance of the il-2 gene locus in human MS and its possible involvement in other autoimmune diseases.