MicroRNA and gene expression profiling of response to lithium treatment for bipolar I disorder

Bipolar is a debilitating mood disorder characterized by mixed episodes of depression and mania. It is classified into bipolar I and II according to the occurrences and frequencies of depressive and manic episodes. As the sixth leading cause of disability in the world, bipolar disorder exerts a huge amount of burden on the patient´s family and the society as a whole. Lithium is often the prescribed medication; however, not all patients are responsive to it. In fact, some may even develop adverse drug reactions to the drug. In an attempt to understand the mechanisms underlying the response to lithium among bipolar I patients, we profiled the gene and microRNA expression differences between the good and poor responders in peripheral blood. We identified a number of differentially expressed genes and microRNAs, determined their functions using gene ontology and pathway annotation tools, and assessed the potential interactions between these two types of molecules via target prediction algorithms, association analyses, and existing literature evidence. We found several microRNA-gene interaction biomarkers that differ between the poor and good lithium responders. With future validations, these biomarkers may provide insights into the mechanism underlying lithium response.