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

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 stability 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. Nevertheless, 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 severity 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.