Abstract

Background: The involvement of microRNAs (miRNAs) in neuronal differentiation and synaptic plasticity suggests a role for miRNAs in psychiatric disorders; association analyses and functional approaches were used to evaluate the implication of miRNAs in the susceptibility for panic disorder. Methods: Case-control studies for 712 single-nucleotide polymorphisms (SNPs) tagging 325 human miRNA regions were performed in 203 Spanish patients with panic disorder and 341 control subjects. A sample of 321 anxiety patients and 642 control subjects from Finland and 102 panic disorder patients and 829 control subjects from Estonia was used as a replica. Reporter-gene assays and miRNA overexpression experiments in neuroblastoma cells were used to functionally evaluate the spectrum of genes regulated by the associated miRNAs. Results: Two SNPs associated with panic disorder: rs6502892 tagging miR-22 (p<.0002), and rs11763020 tagging miR-339 (p<.00008). Other SNPs tagging miR-138-2, miR-488, miR-491, and miR-148a regions associated with different panic disorder phenotypes. Replication in the north-European sample supported several of these associations, although they did not pass correction for multiple testing. Functional studies revealed that miR-138-2, miR-148a, and miR-488 repress (30%-60%) several candidate genes for panic disorder-GABRA6, CCKBR and POMC, respectively and that miR-22 regulates four other candidate genes: BDNF, HTR2C, MAOA, and RGS2. Transcriptome analysis of neuroblastoma cells transfected with miR-22 and miR-488 showed altered expression of a subset of predicted target genes for these miRNAs and of genes that might be affecting physiological pathways related to anxiety. Conclusions: This work represents the first report of a possible implication of miRNAs in the etiology of panic disorder.