One work worth mentioning is a study from 2019 including the most common psychiatric disorders, which summarized the result of previous different meta-analyses and reported that IL-4 and soluble IL-6 receptor (sIL-6R) are consistently elevated only in BD (but not in major depressive disorder [MDD], schizophrenia, and autism spectrum disorder). The gene discussed is IL6R; the disease is major depressive disorder.