IFN-α and TNF-α production by pDCs upon TLR-9 and TLR-7 stimulation was severely impaired (< 1% of CD123+ IFN-α+/TNF-α+) in 36% (14 subjects) and 33% (13 subjects) of SLE subjects, respectively. This evidence concerns the gene IFNA1 and systemic lupus erythematosus.