QT length during methadone maintenance treatment: gene × dose interaction

Area of Science:

• Pharmacogenetics
• Cardiology
• Genetics

Background:

• Methadone maintenance treatment is associated with QT interval prolongation, a risk factor for sudden cardiac death.
• QTc interval changes can be influenced by drug-pharmacology interactions and individual genetic predispositions.
• Identifying genetic markers associated with QTc prolongation is crucial for patient safety during methadone therapy.

Purpose of the Study:

• To investigate the association between single nucleotide polymorphisms (SNPs) in key cardiac genes and QTc interval length in patients undergoing methadone treatment.
• To explore the potential interaction between genetic variations, methadone dosage, and QTc interval prolongation.
• To identify specific genetic factors that may predict an increased risk of QTc prolongation in this patient population.

Main Methods:

• Recruitment of 154 former heroin-dependent subjects on methadone maintenance treatment.
• Genotyping of 126 SNPs across five genes (KCNE1, KCNQ1, KCNH2, NOS1AP, SCN5A) known to be involved in drug-induced QT prolongation.
• Statistical analysis including SNP-based and gene-based approaches, Pearson correlation for methadone dosage, and interaction analysis between top SNP and methadone dose.

Main Results:

• Methadone daily dose showed a significant association with QTc length (r=0.26, P=10⁻³).
• The SNP rs11911509 on the KCNE1 gene was significantly associated with QTc length after multiple testing correction (P=3.84×10⁻⁴; p_corrected=0.049).
• A significant interaction was found between methadone dosage and rs11911509 genotype (P=0.01), with QTc prolongation correlation primarily observed in AA carriers.

Conclusions:

• Genetic background, particularly variations in the KCNE1 gene (rs11911509), plays a role in QTc interval prolongation during methadone treatment.
• The interaction between methadone dosage and specific genetic variants influences the degree of QTc prolongation.
• Personalized risk assessment considering genetic factors may be warranted for patients at risk of significant QTc enlargement during methadone therapy.