This was more prominent in the RA cohort where 8 IFN genes, including EPSITI1, IFI44, ISG15, MS4A4A, OASL, RTP4, serpin peptidase inhibitor, clade G (C1 inhibitor), member 1 (SERPING1) and SIGLEC1, were uniquely overexpressed (Additional File 2A). This evidence concerns the gene ISG15 and rheumatoid arthritis.