OBJECTIVE: Inclusion body myositis (IBM) is characterized by a combination of inflammatory and degenerative changes affecting muscle. While the primary cause of IBM is unknown, genetic factors may influence disease susceptibility. To determine genetic factors contributing to the etiology of IBM, we conducted the largest genetic association study of the disease to date, investigating immune-related genes using the Immunochip. METHODS: A total of 252 Caucasian patients with IBM were recruited from 11 countries through the Myositis Genetics Consortium and compared with 1,008 ethnically matched controls. Classic HLA alleles and amino acids were imputed using SNP2HLA. RESULTS: The HLA region was confirmed as the most strongly associated region in IBM (P = 3.58 × 10(-33) ). HLA imputation identified 3 independent associations (with HLA-DRB1*03:01, DRB1*01:01, and DRB1*13:01), although the strongest association was with amino acid positions 26 and 11 of the HLA-DRB1 molecule. No association with anti-cytosolic 5'-nucleotidase 1A-positive status was found independent of HLA-DRB1*03:01. There was no association of HLA genotypes with age at onset of IBM. Three non-HLA regions reached suggestive significance, including the chromosome 3 p21.31 region, an established risk locus for autoimmune disease, where a frameshift mutation in CCR5 is thought to be the causal variant. CONCLUSION: This is the largest, most comprehensive genetic association study to date in IBM. The data confirm that HLA is the most strongly associated region and identifies novel amino acid associations that may explain the risk in this locus. These amino acid associations differentiate IBM from polymyositis and dermatomyositis and may determine properties of the peptide-binding groove, allowing it to preferentially bind autoantigenic peptides. A novel suggestive association within the chromosome 3 p21.31 region suggests a role for CCR5.

• MeSH
• autoprotilátky imunologie   MeSH
• běloši genetika   MeSH
• genetická predispozice k nemoci MeSH
• genetické asociační studie MeSH
• HLA-DRB1 řetězec genetika   MeSH
• lidé MeSH
• lidské chromozomy, pár 3 genetika   MeSH
• myozitida s inkluzními tělísky genetika   imunologie   MeSH
• receptory CCR5 genetika   MeSH
• věk při počátku nemoci MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH

OBJECTIVES: The diagnosis of inclusion body myositis (IBM) can be challenging as it can be difficult to clinically distinguish from other forms of myositis, particularly polymyositis (PM). Recent studies have shown frequent presence of autoantibodies directed against cytosolic 5'-nucleotidase 1A (cN-1A) in patients with IBM. We therefore, examined the autoantigenicity and disease specificity of major epitopes of cN-1A in patients with sporadic IBM compared with healthy and disease controls. METHODS: Serum samples obtained from patients with IBM (n=238), PM and dermatomyositis (DM) (n=185), other autoimmune diseases (n=246), other neuromuscular diseases (n=93) and healthy controls (n=35) were analysed for the presence of autoantibodies using immunodominant cN-1A peptide ELISAs. RESULTS: Autoantibodies directed against major epitopes of cN-1A were frequent in patients with IBM (37%) but not in PM, DM or non-autoimmune neuromuscular diseases (<5%). Anti-cN-1A reactivity was also observed in some other autoimmune diseases, particularly Sjögren's syndrome (SjS; 36%) and systemic lupus erythematosus (SLE; 20%). CONCLUSIONS: In summary, we found frequent anti-cN-1A autoantibodies in sera from patients with IBM. Heterogeneity in reactivity with the three immunodominant epitopes indicates that serological assays should not be limited to a distinct epitope region. The similar reactivities observed for SjS and SLE demonstrate the need to further investigate whether distinct IBM-specific epitopes exist.

• MeSH
• 5'-nukleotidasa imunologie   MeSH
• autoimunitní nemoci imunologie   MeSH
• autoprotilátky imunologie   MeSH
• dermatomyozitida diagnóza   imunologie   MeSH
• diabetes mellitus 1. typu imunologie   MeSH
• dospělí MeSH
• lidé středního věku MeSH
• lidé MeSH
• myozitida s inkluzními tělísky diagnóza   imunologie   MeSH
• neuromuskulární nemoci imunologie   MeSH
• polymyozitida diagnóza   imunologie   MeSH
• revmatoidní artritida imunologie   MeSH
• ROC křivka MeSH
• roztroušená skleróza imunologie   MeSH
• senioři MeSH
• senzitivita a specificita MeSH
• Sjögrenův syndrom imunologie   MeSH
• studie případů a kontrol MeSH
• systémová sklerodermie imunologie   MeSH
• systémový lupus erythematodes imunologie   MeSH
• Check Tag
• dospělí MeSH
• lidé středního věku MeSH
• lidé MeSH
• mužské pohlaví MeSH
• senioři MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• srovnávací studie MeSH