The invention relates to the field of medical diagnostics. More specifically, the invention relates to methods to diagnose or screen for inflammatory conditions or disease, including auto-inflammatory disease and affective disorder, in a subject, preferably a human subject, by assaying for a marker for an inflammatory disease. Provided is a method to diagnose, screen for or predict the development of an affective disorder (AD), preferably bipolar disorder (BP), in a subject, the method comprising determining the level of at least one, preferably at least two, more preferably at least three, most preferred at least four, AD-specific gene product(s) in a biological sample isolated from the subject, preferably peripheral blood monocytes, wherein the gene is selected from the group comprising ATF3, phosphodiesterase 4 B, CXCL2, BCL2-related protein A2, Dual specificity phosphatase 2, TNFα-induced protein 3 / A20, BTEB1 CXCL3, Chemokine CCL-3 like, CCL-4, CCL20, CX2CR1, Amphiregulin, Thrombomodulin, Heparin-binding EGF-like growth factor, DNA-damaged inducible transcript, V28 chemokine-like receptor, TRAIL. MAPK6, B4BP4, PBEF1, Thrombospondin 1, MAFF, HSP70, CCL2, MCP-3, CCR2, CX3CR1, DOK1, HBB, G-gamma globin, THBD, PHLDA1, DTR and GNLY.