Interestingly, all of the 14 SLE subjects with impaired TLR-9 induced IFN-α production and 11 of 13 with impaired TLR-7 induced IFN-α production were being treated with HCQ (impaired TLR-9/IFN-α; HCQ vs no HCQ; P = 0.0003) (impaired TLR-7/IFN-α; HCQ vs no HCQ; P = 0.07). Here, TLR9 is linked to systemic lupus erythematosus.