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. Study Highlights WHAT IS THE CURRENT KNOWLEDGE ON THE TOPIC?There is limited knowledge concerning distal cis-acting regulatory elements and genetic variants controlling expression of the CYP3As.

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Background: Approximately 3 million Americans have ill managed lipidemia due to statin intolerance (SI) or statin-associated myopathy (SAM). Atorvastatin and simvastatin are the most prescribed statins which are transported into the liver by SLCO1B1 and metabolized by cytochrome P450 (CYP) 3A4 and 3A5. CYP3A4*22 and CYP3A5*3 are two polymorphisms known to decrease their activity; thus, increasing the systemic daily exposure (AUC) and serum concentration (C max ) of unmetabolized statin. In Caucasian (CAU) populations the prevalence [5-7% CYP3A4*22 and 90% CYP3A5*3] and effect of these polymorphisms is well characterized but not in African American (AA) populations. We hypothesize that the prevalence of SI and SAM are correlated with CYP3A4/5 polymorphisms in AA populations. Methods: After IRB approval, saliva samples were collected from patients currently prescribed atorvastatin or simvastatin at The Ohio State University Medical for genotyping. SLCO1B1 status was assessed to control for its confounding effect. Participants with polymorphic results were contacted to complete 8 blood draws over 13hrs for pharmacokinetic analysis. Electronic medical records were utilized to collect demographic information, medical histories, risk factors, and concomitant medications. Results: Preliminary analysis of 502 participants (395 AA, 104 CAU, and 3 others) shows racially different polymorphic prevalence. Reduced activity of CYP3A4 was present in 5.8% CAU vs 0.51% AA. Notably, CYP3A5*3 is inactive in 73% and reduced in 20.3% of CAU compared to 41.7% and 40.7% respectively in AA. A statistically significant increase in SI in AA women vs CAU women (p=0.0032) was observed. In combined analysis, atorvastatin has reduced odds of intolerance compared to simvastatin (OR=0.463; p <0.05). However, the odds of SAM is higher in patients with no history of cardiovascular disease (OR=6.137; p <0.01) and those with chronic kidney disease (OR=1.269; p <0.05). Clinical significance: Considering, the CYP3A5 is fully active in 18.5% of the AA population compared to 6.8% CAU, the characterization of this metabolic enzyme is of clinical significance in minority populations to better manage lipidemia, assess the safety profile of current therapeutic doses, and reduce SAM.

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