Does DRD2 polymorphism influence the clinical characteristics of prolactinoma?

Objectives: Genetic alterations explaining the clinical variability of prolactinomas still could not be clarified and dopamine D2 receptor (DRD2) polymorphism is a putative candidate for the variable response to dopaminergic treatment. The present study was conducted to investigate the influence of DRD2 TaqI A polymorphism on initial and follow-up characteristics of prolactinoma.

Patients And Methods: Seventy-two patients with prolactinoma and 98 age and gender matched control subjects were recruited to the case-control study. Serum prolactin levels were assessed by enzyme-linked immunosorbent assay and DRD2 polymorphism was determined by polymerase chain reaction and restriction length polymorphism analysis.

Results: Decrease of prolactin levels and the tumor shrinkage after cabergoline treatment were 93.9±5.9% and 58.3±33.1% in microadenomas and 96.1±6.1% and 51.7±29.3 in macroadenomas (P=0.02 and P>0.05, respectively). We observed no significant difference for DRD2 genotypes and the alleles between the patients and healthy group (P>0.05). Prolactin levels before treatment were correlated with tumor diameter before and after treatment and the percentage of prolactin decrease with treatment (P<0.001 r=0.58, P<0.001 r=0.40 and P<0.001 r=0.47, respectively). Tumor diameter before the treatment was also correlated with the tumor diameter after the treatment (P<0.001 r=0.64) and the percentage of prolactin decrease (P=0.01 r=0.30). However, no significant association was found between characteristics of prolactinoma and DRD2 genotypes and alleles (P>0.05).

Conclusion: This study revealed that DRD2 TaqI A receptor polymorphism was not associated with the development of prolactinoma and its clinical characteristics. Future studies are needed to clarify the clinical implications of genetic alterations in prolactinoma.