Familial Hypercholesterolemia –Defective cholesterol receptors on liver cells Fail to filter cholesterol from blood properly Cholesterol levels are elevated, increasing risk of heart attacks and strokes –1993  First attempt Retroviral vector used to infect 3.2 x 10 9 liver cells (~15% of patients liver) ex vivo –Infused back into patient –Improvement seen –Has been used in many trials since then Single Gene Defects = Most Attractive Candidates
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