IFNA17 and mixed connective tissue disease: Analysis of IFN-α/-β/-γ levels in serum in MCTD patients and healthy subjects in relation to all examined IFN-A/-B/-G genetic variants revealed no association between IFN-A/-B/-G different genotypes and IFN-α/-β/-γ levels in serum among MCTD patients and as well as in the control groups.