Entering a new phase of immunogenetics in the idiopathic inflammatory myopathies.

[inclusion body myositis]

To review the progress that has been made in understanding the genetics of the idiopathic inflammatory myopathies (IIMs ) in the past 2 years , with particular focus on polymyositis , dermatomyositis and inclusion body myositis .Candidate gene studies in the Japanese population have implicated signal transducer and activator of transcription 4 as a risk locus for IIM , and HLA-DRB 1 as a risk locus for anti-melanoma differentiation-associated gene 5 -positive dermatomyositis . Evidence for gene -environment interactions has been found between HLA-DRB 1 *03 and smoking as a risk factor for the development of anti-histidyl tRNA synthetase antibodies , and HLA-DRB 1 *11 :01 and statins for the development of anti-hydroxymethyl glutaryl-coenzyme A reductase-positive statin-induced myopathy . The HLA-DRB 1 *03 :01 /*01 :01 genotype confers the highest disease risk in inclusion body myositis . A recent genome-wide association study has been performed in dermatomyositis . The most significant signals were in the major histocompatibility complex region , with other loci suggesting evidence of genetic overlap with different autoimmune diseases .Recent association and gene -environment interaction studies have increased our knowledge of genetic risk factors for the IIMs . Ongoing international collaborations will facilitate larger and more meaningful genetic studies revealing much about the genetic architecture of these complex diseases .