Furthermore, genetic mutations in the genes encoding various cytokines (e.g., IL-1β, IL-6, IL-10, TNF-α, C-reactive protein) have been identified as risk factors for MDD development, and cytokine mRNA expression (especially IL-1β) can be used to help identify patients who will be resistant to traditional MDD pharmacological therapies (Barnes et al., 2017). Here, IL1B is linked to major depressive disorder.