MB and acquired idiopathic inflammatory myopathy: Decreased serum levels of 1,25(OH)D, were observed in IIM patients compared to HCs.Gene expression of VDR and CYP27B1 was numerically higher in the muscle tissue of IIM patients compared to HCs.After a 24-week training program, VDR and CYP27B1 gene expression in primary muscle cells decreased in IIM patients.VDR gene expression in muscle tissue was associated with different disease parameters in IIMs, including myoglobin levels, muscle strength (MMT8) and creatine kinase (CK).