From SNPedia
rs1128503 is a SNP in the transporter P-glycoprotein (P-gp) 170, encoded by the
ABCB1 (also known as MDR1) gene.
Methadone is a substrate of this protein, so variants may affect the efficacy and optimal dosage of this drug as used for treating opiate dependence.
A study of 98 methadone-maintaining patients concluded that the higher (>150 mg/day) and lower (< or =150 mg/day) methadone dose groups differed significantly in their rs1128503 status (experiment-wise p = 0.0325). Furthermore, individuals with the 3-locus genotype pattern (T;T)-(T;T)-(T;T) for SNPs rs1045642, rs2032582 and rs1128503, respectively, had an approximately 5-fold chance of requiring the 'higher' methadone dose, while individuals heterozygous for these three SNPs have an approximately 3-fold chance of stabilizing at the 'lower' methadone dose (point-wise p-value = 0.026).[PMID 18424454]
| ? | (C;C) (C;T) (T;T) |
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[PMID 19107781] Associations between ABCB1/MDR1 gene polymorphisms and Crohn's disease: a gene-wide study in a pediatric population
[PMID 19437139] ABCB1 single nucleotide polymorphisms in the Brazilian population
