NDRG2 and pituitary gland adenoma: This is the first study that has demonstrated the NDRG2 gene promoter methylation and mRNA expression in patients with diagnoses of pituitary adenoma and analyzed the relationships between NDRG2 epigenetic changes and the association with PA clinical features including patient age, gender, relapse, hormone groups, invasiveness, diagnoses of prolactinoma, acromegaly and Cushing syndrome.