The frequency of pain crises in patients with sickle cell disease is quite variable. Some patients never experience pain crises while others can have 3 or more crises per year. In the monoamine neurotransmitter systems, both catechol-O-methyltransferase (COMT) and dopamine D3 receptor (DRD3) genes have single nucleotide polymorphisms (SNP) that influence pain perception. The relationship […]