In order to determine the etiology of myositis, antibodies (IgG) against 11 antigens associated with myositis, IgG against 18 antigens associated with myopathies, antibodies against antigens of heart and skeletal striated muscles, muscle-specific tyrosine kinase, IgG against 23 nuclear antigens (ANA), anti-double-stranded deoxyribonucleic acid antibodies (anti-dsDNA), antineutrophil cytoplasmic antibodies (ANCA), and genetic acylcarnitine profile analysis were performed. The gene discussed is BTG3; the disease is myositis disease.