Few associations replicated: morphine dose (mcg/kg) in African American children and ABCB1 rs1045642 (A allele, β = -9.30, 95% CI: -17.25 to -1.35, p = 0.02) and OPRM1 rs1799971 (G allele, β = 23.19, 95% CI: 3.27-43.11, p = 0.02); KCNJ6rs2211843 and high pain in African American subjects (T allele, OR 2.08, 95% CI: 1.17-3.71, p = 0.01) and in congruent European Caucasian pain phenotypes; and COMT rs740603 for high pain in European Caucasian subjects (A allele, OR: 0.69, 95% CI: 0.48-0.99, p = 0.046).
Patients with the COMT G472A-AA genotype (rs4680) and KCNJ6A1032G-A allele (rs2070995) CLBP responded differently to opioid titration, with higher pain intensity requiring higher dosing.
Therefore, over expression of GIRK2 in the brain is necessary, but not sufficient to confer susceptibility to the GABA<sub>B</sub>R agonist-induced IS phenotype in the Ts model of DS.