Acute pain and opioid analgesia demonstrate inter-individual variability and polygenic influence. In 241 children of African American and 277 of European Caucasian ancestry, we sought to replicate select candidate gene associations with morphine dose and postoperative pain and then to estimate dose prediction limits. Twenty-seven single nucleotide polymorphisms (SNPs) from 9 genes (
ABCB1, ARRB2, COMT, DRD2, KCNJ6, MC1R, OPRD1, OPRM1, UGT2B7
) met selection criteria and were analyzed along with
TAOK3
. Few associations replicated: morphine dose (mcg/kg) in African American children and
ABCB1
rs1045642 (A allele, ß=−9.30, 95% CI −17.25–−1.35, p=0.02) and
OPRM1
rs1799971 (G allele, ß=23.19, 95% CI 3.27–43.11, p=0.02);
KCNJ6
rs2211843 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). With age, body mass index, and physical status as covariates, simple top SNP candidate gene models could explain theoretical maximums of 24.2% (European Caucasian) and 14.6% (African American) of morphine dose variances.