Knisely MR, et al. - Researchers sought to evaluate the associations between breast pain phenotypes and single nucleotide polymorphisms (SNPs) among 15 genes involved in catecholaminergic and serotonergic neurotransmission. Mild Pain class was noted to be associated with polymorphisms in five genes: ADRB2 rs2400707, ADRBK2 HapA04, HTR3A rs10160548, SLC6A2 rs1566652, and TPH2 rs11179000. The Moderate Pain class showed an association with polymorphisms in three genes: HTR2A rs2296972, SLC6A2 rs17841327, and SLC6A3 rs403636. Polymorphisms in three genes were noted to be associated with membership in the Severe Pain class: COMT HPS haplotype, SLC6A2 HapD01, and SLC6A3 rs464049. These associations suggested possible underlying mechanisms that play a role in the development and severity of persistent breast pain.