1. Introduction: The Road to Gene Therapy 2. Driving AAV Drug Design to the Right Place, Right Amount, and Right Time 3. A Practical Guide to the Nonclinical Development of In Vivo Gene Therapies 4. Quantitative Systems Pharmacology Modeling of Adeno-Associated Virus Gene Therapies: Mechanistic Identification of Species-Translation Using Preclinical and Clinical Data 5. Bringing Gene Therapy to Patients: A Clinical Development Perspective Based on Brain and Neuromuscular Diseases 6. The Ethics of Gene Therapy 7. AAV Vector Immunogenicity in Gene Therapy: Mechanisms, Assessment, and Immunomodulation Strategies 8. Prenatal Somatic Cell Gene Therapy 9. Development of Gene Therapies for Ultra-Rare Disease 10. Statistical Innovation for Gene Therapy Development: Clinical Trial Design and Analysis Considerations 11. Biomarkers in Gene Therapy Development for Rare Diseases 12. Manufacturing, Analytical, and Process Comparability Challenges for Recombinant Adeno-Associated Virus (rAAV) Gene Therapy 13. Regulatory Considerations in the Development of Gene Therapy Products 14. Gene Therapy Clinical Safety Considerations: Short- and Long-Term 15. Development of Gene Therapies from an Academic Perspective 16. Commercial Models, Access Hurdles, and Health Economics of Gene Therapies 17. The Zolgensma Journey: A Groundbreaking Therapy for SMA 18. History and Development Story of Luxturna: Scientific and Regulatory Challenges 19. The Future of in vivo rAAV Gene Therapies for Rare Neurological Diseases