Knisely MR, et al. - Researchers evaluated genetic factors that contribute to persistent arm pain following breast cancer surgery by assessing 15 genes involved in catecholaminergic and serotonergic neurotransmission and determining how persistent arm pain phenotypes are associated with genetic polymorphisms. As per rating by 398 women regarding the presence and intensity of arm pain, patients were classified as no arm pain (41.6%), mild arm pain (23.6%), and moderate arm pain (34.8%). Compared with cases in the no arm pain group, cases in the mild arm pain group were linked with three single nucleotide polymorphisms and one haplotype, in four genes (COMT rs4633, HTR2A haplotype B02, composed of rs1923886 and rs7330636, HTR3A rs1985242, and TH rs2070762) and cases in the moderate arm pain class were linked with four single nucleotide polymorphisms in three genes (COMT rs165656, HTR2A rs2770298 and rs9534511, and HTR3A rs1985242). Findings thereby suggest there is a part played by catecholaminergic and serotonergic gene variations in the development of persistent arm pain.