Inclusion Criteria:  8-21 years LDL cholesterol >130mg/dl (>95% percentile) SLCO1B1 c.521TT genotype Provide informed permission-assent(<18 yrs.) or consent (≥18 yrs.) Fasting overnight (~8 hrs.) Enrolled in Cardiology Pharmacogenomic Repository  Exclusion Criteria:  Pregnancy Non-fasting Non-removable metal in body or MRI unsafe Currently on or history of statin therapy Underlying congenital or acquired hemodynamically CV disease History of underlying or laboratory evidence of underlying intestinal, metabolic, autoimmune, renal disease that can alter rosuvastatin disposition * (absorption, metabolism, distribution, or clearance) Pharmacotherapy that interact with statins (OATP1B1 inducers/inhibitors) *  Inability to swallow a tablet  •>3x the age-specific upper limit of normal for AST, ALT, total and conjugated bilirubin  Diarrhea in the last 24 hours