Beta2-Adrenergic Receptor Polymorphisms and Haplotypes Associate With Chronic Pain in Sickle Cell Disease

Abstract

Pain in sickle cell disease (SCD) is severe, variable, and inadequately comprehended. The β2-adrenergic receptor (<i>ADRB2</i>) is critical in mediating neurotransmitter response in the sympathetic nervous system. In this association study, we examined 16 single nucleotide polymorphisms (SNPs) covering 5'-UTR and coding regions of <i>ADRB2</i> for pain variability in SCD. Subjects recorded their non-crisis, baseline pain experience on a computerized tool from which we obtained chronic pain measurement score- composite pain index (CPI). Regression models yielded significant associations between chronic pain and seven SNPs. Non-synonymous SNP rs1042713 A allele (Arg16) caused a 5.73-fold decrease in CPI (<i>p</i> = 0.002). Allele A of rs12654778 and T of rs17778257 reduced CPI by a fold of 4.52 (<i>p</i> = 0.019), and 4.39 (<i>p</i> = 0.032), respectively. Whereas, in the 5' UTR, allele C of rs1042711, G of rs11168070, C of rs11959427, and C of rs1801704 increased CPI by a fold of 10.86 (<i>p</i> = 0.00049), 5.99 (<i>p</i> = 0.016), 5.69 (<i>p</i> = 0.023), and 5.26 (<i>p</i> = 0.031), respectively. Together, these SNPs accounted for 2-15% of CPI variance after adjusting for covariates. Moreover, these SNPs were in high linkage disequilibrium (LD) showing three LD blocks in our cohort. A 10-marker haplotype increased CPI by 11.5-fold (<i>p</i> = 0.000407). Thus, <i>ADRB2</i> polymorphisms might contribute to chronic pain severity and heterogeneity in SCD.