Welcome to Gene Therapy Science / Learning Center

Learning Center

Welcome to the Hemophilia Gene Therapy Learning Center. Here you will find links to further resources to explore the topics on this website in more detail.

Resources include:

Webinars

The Hemophilia Gene Therapy Webinar Series will explore the complex science underpinning hemophilia gene therapy. Hosted by an expert hematologist, joined by a specialist, each webinar will focus on providing a high-science review of key areas of interest in hemophilia gene therapy.

The Journey of the DNA in Hemophilia Gene Therapy

Gerry Dolan and Thierry VandenDriessche explore the complex processes involved in gene therapy, from transgene packaging to expression of the protein of interest.

Gene Therapy and the Liver

Andreas Tiede and Heiner Wedemeyer explore the role of the liver in hemophilia gene therapy, including its physiology, its tolerogenic nature, and key considerations for liver-targeted gene therapy.

From Virus to Vector: Exploring the building blocks of adeno-associated virus capsid design

Lindsey George and Jude Samulski investigate key characteristics of adeno-associated virus as a platform to produce recombinant vectors for gene therapy, including current understanding of its dynamics and function.

Brochures

The Hemophilia Gene Therapy Brochures are complementary to the webinar series. Each brochure delves deeper into the topic covered during the webinar episode. These can be viewed online or downloaded using the links below.

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Hemophilia Gene Therapy: Key Principles

Explore and advance your understanding of the basic principles of hemophilia gene therapy.

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The Liver Takes a Leading Role in the Hemophilia Gene Therapy Story

Explore the role of the liver in hemophilia gene therapy including its physiology, its tolerogenic nature, and key considerations for liver-targeted gene therapy.

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Recombinant adeno-associated virus vectors: from virus to therapeutic vector

Understand key characteristics of adeno-associated virus as a platform to produce recombinant vectors for gene therapy, including approaches to vector design and production of rAAV vectors.

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Optimizing transgene expression for hemophilia gene therapy

Learn more about the recombinant adeno-associated virus transgene expression cassette, how it can be optimized, and its role in hemophilia gene therapy. 

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Understanding pre-existing immunity against AAV: implications for hemophilia gene therapy

Understand how pre-existing immunity against AAV or AAV seroprevalence is an important consideration for hemophilia gene therapy

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Immune responses associated with hemophilia gene therapy

Discover and explore the immunological considerations for hemophilia gene therapy including immune responses to rAAV and strategies to address immunity post-administration

Educational Videos

The following videos provide additional educational content around the key concepts important for understanding hemophilia gene therapy.
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Glossary

3’ (3 prime)

3' refers to the end of a single-stranded nucleic acid chain to which a hydroxyl group (-OH) is attached to the 3'-carbon atom of the nucleotide. 1

5’ (5 prime)

5' refers to the end of a single-stranded nucleic acid chain to which a phosphate is attached to the 5'-carbon atom of the nucleotide.1

Capsid

The capsid is the protein shell of a virus that protects the genetic material while interacting with the host environment.2 Capsid proteins determine cell-type specificity.3

Chromosome

A chromosome is an organized package of DNA found in the nucleus of a cell. Humans have 23 pairs of chromosomes–22 pairs of numbered chromosomes, called autosomes, and one pair of sex chromosomes, X and Y.4

Codon

A codon is a sequence of three nucleotides that codes a specific amino acid. For DNA, there are four different nucleotides (A, T, C, or G) from which a codon can be composed.5

Endocytosis

A cellular process by which substances are brought into a cell. The substance is surrounded by an area of cell membrane, which then buds off inside the cell to form a vesicle containing the ingested material.6

Enhancer

An enhancer is an upstream regulatory DNA sequence that provides binding sites to regulatory proteins and can augment the activity of a promoter.7

Episome

Exogenous DNA that remains physically independent of the cell’s endogenous chromosome or complement of chromosomes.8

Ex vivo gene therapy

Harvesting and cultivating of patient cells in the laboratory. Cells are incubated with vectors carrying a corrective or therapeutic gene. Cells with the new genetic information are then transplanted back into the patient from whom they were derived.9

Gene editing

Removal, disruption or correction of faulty elements of DNA within the gene.10

Gene transfer (gene addition)

Addition of a functional copy of a missing gene or augmentation of a gene that is non-functional into target cells to produce more of a protein.10,11

Immunogenicity

The ability of a substance, such as an antigen or epitope, to trigger an immune response in the host.12

Intron

An intron is a portion of DNA that does not code for an amino acid.13

Inverted terminal repeats (ITRs)

ITRs are 145-bp sequences that frame the expression cassette.14

In vivo

Administration of a vector carrying the therapeutic genetic material to a live animal. The vector can be delivered by a variety of methods, including direct injection into the blood (intravenous injection) or by various organs by other physical means of administration (hypodermic injection, aerosol, intrathecal, etc.).9

Messenger RNA (mRNA)

Single molecule of RNA that works as a chemical map for a protein product.9

Nucleus

Membrane-bound organelle that contains the cell's chromosomes. Pores in the nuclear membrane allow for the passage of molecules in and out of the nucleus.15

Plasmid

An extrachromosomal, self-replicating piece of DNA. Plasmids are usually circular and transferable between cells.16

Promoter

Sequence of DNA, typically at the 5’ region, where regulatory elements such as transcription factors bind and initiate transcription of the associated gene.17

Proteasome

A large protease complex which selectively degrades proteins by proteolysis. The proteasome works in collaboration with ubiquitin–polymerization of ubiquitin serves as a degradation signal that transports the target proteins to the proteasome for degradation.18

Seroprevalence

The proportions of individuals within a population with an antibody to a serotype. Seroprevalence is measured in blood serum.19

Serotype

Group of closely related microorganisms distinguished by a characteristic set of antigens and detected by an antibody.9

Terminator sequence (Poly(A))

The Poly(A) signal sequence acts as the transcription terminator, halting transcription once the transgene is fully transcribed.20

Transduction

Transfer of genetic material into the nucleus of a cell, such that elements of the newly transferred DNA are then expressed. This can be accomplished naturally by a virus or other vector or experimentally by augmenting the receptivity of the cell membrane of the recipient cell with chemicals or electricity.21

Transfer RNA (tRNA)

tRNAs act as adaptors between the mRNA and the amino acids during translation. The tRNA has an anticodon loop that binds to the complementary mRNA codon and also has a bound amino acid.22

Transgene

The transgene is the nucleic acid sequence encoding an artificially added gene.23

Tropism

The ability of a virus to infect a particular type of cell in the body.23
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Vector

A gene therapy delivery vehicle, which encapsulates a therapeutic gene and delivers it to target cells. Vectors can be either virus-derived or non-viral.9

References1. Nature Scitable: Glossary (others). www.nature.com/scitable/glossary/#othrsLnkGlo (Accessed September 2023). 2. Thomas CE, et al. Nat Rev Genet 2003;4:346–58. 3. George LA. Blood Adv 2017;1(26):2591–9. 4. National Institutes of Health: Genetics glossary (chromosome). www.genome.gov/genetics-glossary/Chromosome (Accessed September 2023). 5. National Institutes of Health: Genetics glossary (codon). www.genome.gov/genetics-glossary/Codon (Accessed September 2023). 6. Cooper GM. The Cell: A Molecular Approach. 2nd Edition. Sunderland (MA): Sinauer Associates, 2000. Endocytosis. www.ncbi.nlm.nih.gov/books/NBK9831/ (Accessed September 2023). 7. Nature Scitable: Glossary (gene expression). www.nature.com/scitable/topicpage/gene-expression-14121669/ (Accessed September 2023). 8. NEJM Illustrated Glossary (episome): https://illustrated-glossary.nejm.org/term/episome (Accessed September 2023). 9. American Society of Gene and Cell Therapy: Glossary. www.asgct.org/education/more-resources/glossary (Accessed September 2023). 10. American Society of Gene and Cell Therapy: Gene and Cell Therapy FAQs. www.asgct.org/education/more-resources/gene-and-cell-therapy-faqs (Accessed September 2023). 11. National Hemophilia Foundation: Future Therapies FAQs.https://www.hemophilia.org/bleeding-disorders-a-z/treatment/future-therapies/frequently-asked-questions (Accessed September 2023). 12. NEJM Illustrated Glossary (immunogenicity): https://illustrated-glossary.nejm.org/term/immunogenicity (Accessed September 2023). 13. National Institutes of Health: Genetics glossary (intron). www.genome.gov/genetics-glossary/Intron (Accessed September 2023). 14. Li C, Samulski RJ. Nat Rev Genet 2020;21(4):255–72. 15. National Institutes of Health: Genetics glossary (nucleus). www.genome.gov/genetics-glossary/Nucleus (Accessed September 2023). 16. NEJM Illustrated Glossary (plasmid): https://illustrated-glossary.nejm.org/term/plasmid (Accessed September 2023). 17. Ohmori T. Int J Hematol 2020;111:31–41. 18. Tanaka K. Proc Jpn Acad 2009;85:12–36. 19. Merriam-Webster Definition (seroprevalence). www.merriam-webster.com/dictionary/seroprevalence (Accessed September 2023). 20. Tran DP, et al. Mol Cell Biol 2001;21(21):7495–508. 21. NEJM Illustrated Glossary (transduction): https://illustrated-glossary.nejm.org/term/transduction (Accessed September 2023). 22. Cooper GM. The Cell: A Molecular Approach. 2nd Edition. Sunderland (MA): Sinauer Associates, 2000. Translation of mRNA. www.ncbi.nlm.nih.gov/books/NBK9849/ (Accessed September 2023). 23. Sidonio Jr, R. Blood Rev 2021;47:100759.

EM-USA-RDH-0062
Date of preparation: September 2023

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