CD177 and gonorrhea: In another study looking at the polymorphisms of cell surface receptor genes and formation of PAs, Peculis et al. (2016) found that in their cohort of 143 PAs (46 prolactinomas) and 354 case controls, the rs7131056 at the dopamine receptor D2 gene (DRD2) was associated with higher occurrence of extrasellar growth in patients with prolactinomas [38].