Although it is well-established that myeloid cells are the main contributors to the transcriptional whole blood IFN signature observed in SLE patients, we observed that the expression of two canonical IFN signature genes (MX1 and IFH1), but not a housekeeping gene (HPRT1) were highly correlated with the quantitative IFN signature score (Supplementary Figure 6B), indicating that total CD4+ T cells are also contributing to this peripheral transcriptional signature. The gene discussed is HPRT1; the disease is systemic lupus erythematosus.