Background Niacin is a broad-spectrum lipid-modulating drug, but its mechanism of action is unclear. Genome-wide association studies have identified multiple loci associated with blood lipid levels and lipoprotein (a). It is unknown whether these loci modulate response to niacin. Methods and Results Using data from the AIM - HIGH (Atherothrombosis Intervention in Metabolic Syndrome with Low HDL /High Triglycerides and Impact on Global Health Outcomes) trial (n=2054 genotyped participants), we determined whether genetic variations at validated loci were associated with a differential change in plasma lipids and lipoprotein (a) 1 year after randomization to either statin+placebo or statin+niacin in a variant-treatment interaction model. Nominally significant interactions ( P<0.05) were found for genetic variants in MVK , LIPC , PABPC 4, AMPD 3 with change in high-density lipoprotein cholesterol; SPTLC 3 with change in low-density lipoprotein cholesterol; TOM 1 with change in total cholesterol; PDXDC 1 and CYP 26A1 with change in triglycerides; and none for lipoprotein (a). We also investigated whether these loci were associated with cardiovascular events. The risk of coronary disease related death was higher in the minor allele carriers at the LIPC locus in the placebo group (odds ratio 2.08, 95% confidence interval 1.11-3.90, P=0.02) but not observed in the niacin group (odds ratio 0.89, 95% confidence interval 0.48-1.65, P=0.7); P-interaction =0.02. There was a greater risk for acute coronary syndrome (odds ratio 1.85, 95% confidence interval 1.16-2.77, P=0.02) and revascularization events (odds ratio 1.64, 95% confidence interval 1.2-2.22, P=0.002) in major allele carriers at the CYP 26A1 locus in the placebo group not seen in the niacin group. Conclusions Genetic variation at loci previously associated with steady-state lipid levels displays evidence for lipid response to niacin treatment. Clinical Trials Registration URL: https://www.clinicaltrials.gov . Unique identifier: NCT00120289.
Keywords: cholesterol; lipids; lipoprotein (a); niacin; pharmacogenetics; statins.