Idiopathic inflammatory myopathy (IIM) has different forms characterized by immune-mediated inflammation of the striate muscle, CD4-mediated damage (dermatomyositis), and immune alterations [7], such as myositis-specific and myositis-associated antibodies, usually with well-defined clinical patterns that may be more aggressive when IIM is associated with rapidly progressive interstitial lung disease. This evidence concerns the gene CD4 and acquired idiopathic inflammatory myopathy.