Recently, microRNAs (miRNAs), which are small, endogenous, non-coding RNAs (ncRNAs) of 18–23 nucleotides that post-transcriptionally regulate gene expression and are highly expressed in brain3–7, have emerged as essential regulators of neuronal development, differentiation, and neuroplasticity6, 8–11. Understanding the function of miRNAs has led to the recognition of their ability to fine-tune the expression of numerous genes and orchestrate the overall activity of multiple pathway components, thereby positioning them to link numerous genetic risk factors for complex human genetic disorders into functional networks. An abundant literature now links miRNAs to neuropsychiatric disorders, especially through the analysis of the 22q11.2 schizophrenia susceptibility locus encompassing the miRNA processing gene DGCR812–15. Moreover, alterations in miRNA profile have been identified in several psychiatric diagnoses including schizophrenia, autism, depression, addiction, and anxiety6, 8, 10, 11, 16–18. Indeed, recent evidence has shown that miR-137, a miRNA located within a locus that is associated with schizophrenia, may target a subset of important disease-related genes19, 20, and potentially explain phenotypic heterogeneity21, 22. However, it remains unclear whether the SNPs in this region implicate miR-137 itself or an adjacent gene23.
