Regulatory variants in a novel distal enhancer regulate the expression of CYP3A4 and CYP3A5.

The cytochrome P450 3As (CYP3As) are abundantly expressed in the liver and metabolize many commonly prescribed medications. Their expression is highly variable between individuals with little known genetic cause. Despite extensive investigation, cis-acting genetic elements that control the expression of the CYP3As remain uncharacterized. Using chromatin conformation capture (4C assays), we detected reciprocal interaction between a distal regulatory region (DRR) and the CYP3A4 promoter. The DRR colocalizes with a variety of enhancer marks and was found to promote transcription in reporter assays. CRISPR-mediated deletion of the DRR decreased expression of CYP3A4, CYP3A5, and CYP3A7, supporting its role as a shared enhancer regulating the expression of three CYP3A genes. Using reporter gene assays, we identified two single-nucleotide polymorphisms (rs115025140 and rs776744/rs776742) that increased DRR-driven luciferase reporter expression. In a liver cohort (n = 246), rs115025140 was associated with increased expression of CYP3A4 mRNA (1.8-fold) and protein (1.6-fold) and rs776744/rs776742 was associated with 1.39-fold increased expression of CYP3A5 mRNA. The rs115025140 is unique to the African population and in a clinical cohort of African Americans taking statins for lipid control rs115025140 carriers showed a trend toward reduced statin-mediated lipid reduction. In addition, using a published cohort of Chinese patients who underwent renal transplantation taking tacrolimus, rs776744/rs776742 carriers were associated with reduced tacrolimus concentration after adjusting for CYP3A5*3. Our results elucidate a complex regulatory network controlling expression of three CYP3A genes and identify two novel regulatory variants with potential clinical relevance for predicting CYP3A4 and CYP3A5 expression.

Association of Genetic Polymorphisms in the Beta-1 Adrenergic Receptor with Recovery of Left Ventricular Ejection Fraction in Patients with Heart Failure.

Two common genetic polymorphisms in the beta-1 adrenergic receptor (ADRB1 Ser49Gly [rs1801252] and Arg389Gly [rs1801253]) significantly affect receptor function in vitro. The objective of this study was to determine whether ADRB1 Ser49Gly and Arg389Gly are associated with recovery of left ventricular ejection fraction (LVEF) in patients with heart failure. Patients with heart failure and baseline LVEF ≤ 40% were genotyped (n = 98), and retrospective chart review assessed the primary outcome of LVEF recovery to ≥ 40%. Un/adjusted logistic regression models revealed that Ser49Gly, but not Arg389Gly, was significantly associated with LVEF recovery in a dominant genetic model. The adjusted odds ratio for Ser49 was 8.2 (95% CI = 2.1-32.9; p = 0.003), and it was the strongest predictor of LVEF recovery among multiple clinical variables. In conclusion, patients with heart failure and reduced ejection fraction that are homozygous for ADRB1 Ser49 were significantly more likely to experience LVEF recovery than Gly49 carriers.