COMT rs4680 and DRD2 rs6275 variants and their association with YMRS scores in children with early-onset bipolar disorder

Abstract

Background and objectives: Bipolar disorder (BD) is a clinical status with at least one manic, hypomanic or mixed attacks. Genetic factors take part significantly in early-onset BD (EOBD). Dopamine receptors (DRD) act in neurological mechanisms like motivation, learning, memory, and, control of neuroendocrine signaling. DRD2 receptor has been reported to influence the sta-bility of DRD2 transcript. Catechol-O-Methyl transferase (COMT) inactivates catecholamines and Val158Met variation on COMT has effects on COMT activity. This study aims to explore DRD2 and COMT variants in the clinical development of EOBD.Methods: In this case-control study, 102 EOBD patients and 168 healthy control subjects were used. DRD2 rs6275 and COMT Val158Met variations were detected by real-time polymerase chain reaction (RT-PCR). Young Mania Rating Scale (YMRS) was utilized to determine the EOBD severity.Results: For DRD2 rs6275 and COMT Val158Met polymorphisms, no significant relationship was observed in the genotype and allele frequencies between patient and control groups. Neverthe-less, TT genotype carriers of DRD2 rs6275 polymorphism demonstrated significantly increased YMRS scores when compared with CC and CT genotype carriers (p = 0.039). Nevertheless, no significant difference was observed between COMT Val158Met genotypes and YMRS scores.Conclusions: We suggest that the DRD2 rs6275 TT variant can be associated with symptom sever-ity in children with EOBD and can have a clinical significance in EOBD pathogenesis. However, these results need to be confirmed with larger samples of patient and control groups.