Role of miRNA Gene Variants (miR-22 and miR-155) as the Factors Affecting Susceptibility to Panic Disorder.

Objective: Variants within genes encoding microRNAs (miRNAs) may alter the expression of both miRNAs and their target genes, thus contributing to the etiology of psychiatric disorders. The involvement of miRNAs in neuronal differentiation and synaptic plasticity supported this hypothesis. We aimed to investigate the links between miR-155 rs767649/miR-22 rs8076112 and the risk of panic disorder (PD) in a sample of Turkish population.

Methods: In this experimental study, 134 PD patients and 140 healthy controls were recruited. Genotyping was carried out using Polymerase Chain Reaction-Restriction Fragment Length Polymorphism (PCR-RFLP) method. To evaluate PD phenotypes, Panic Disorder Severity Scale (PDSS) was also administered to patients to clarify possible associations between the scale and risk variants analyzed.

Results: The genotype analysis of miR-155 rs767649 did not show an association with PD risk and it was not related to the disease severity. For miR-22 rs8076112 variant, a statistically significant association was determined; CC genotypes were lower in patients compared to controls. Logistic regression analysis proved the highly protective effect (80.4%) of CC genotype against PD (p = 0.041; OR = 0.196, 95% CI = 0.041-0.934). Though its significance in disease liability, miR-22 rs8076112 was not associated with the disease severity.

Conclusion: Our findings firstly report the combined analysis of miR-155 rs767649 and miR-22 rs8076112 in PD in terms of both disease susceptibility and severity. These findings await replication in independent cohorts with enrichment of other miRNA gene variants. Thus, certain miRNAs and their target genes involved in the etiology and phenotypes of PD could be enlightened.