Of note, SPEN and RNF40, encoding proteins binding to the Repeat A, the silencing mode of XIST RNA [27, 54, 55] stand as genes with the XIST-interactome that correlate negatively with the X/A-ratio, suggesting they might have an impact on XCI maintenance in immune cells with potential relevance for SLE. The gene discussed is RNF40; the disease is systemic lupus erythematosus.