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Gene Editing Technologies. What is a gene editing technology?. “The use of biotechnological techniques to make changes to specific DNA sequences in the genome of a living organism” (Merriam-Webster, 2018). CRISPR “Clustered regularly interspaced short palindromic repeats”. Theory.
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What is a gene editing technology? “The use of biotechnological techniques to make changes to specific DNA sequences in the genome of a living organism” (Merriam-Webster, 2018)
CRISPR “Clustered regularly interspaced short palindromic repeats” Theory Application Generation of null, conditional, precisely mutated, reporter, or tagged alleles Can insert reporter genes and antibiotic resistance markers (Singh, et al., 2015) • A guide crRNA sequence is chosen based on target site • Complimentary DNA to the crRNA is added to a plasmid vector that also includes a Cas protein and reporter gene • This means when the vector is introduced the crRNA and Cas protein are expressed and edit the genome (Hine & Martin, 2015)
CRISPR - Example • Two human zygotes were edited using CRISPR during IVF with the aim to prevent HIV infection. • The blastocysts were then checked with whole genome sequencing to ensure the mutation had taken hold and everything was safe. • At this stage the now born babies are healthy and the edit seems to have worked, although no official data has yet been published. (The He Lab, 2018) https://www.youtube.com/watch?v=th0vnOmFltc
ZFN “Zinc Finger Nucleases” Theory Applications Gene disruption Gene addition Gene correction (Gaj, et al., 2013) • Around 30 amino acids per finger • Modular structure allows a framework for DNA binding protein design
rAAV “Recombinant Adeno-Associated Viral vectors” Theory Applications Gene therapy for cystic fibrosis hemophilia B, α1-antitrypsin deficiency, Canavan disease, Parkinson’s disease, rheumatoid arthritis, retinal disorders, Duchenne and limb-girdle muscular dystrophy, Huntington’s disease, epilepsy, osteoarthritis, and Alzheimer’s disease (Rey-Rico & Cucchiarini, 2016) • Gene transfer viral vector • Uses the natural cell entry pathways of viruses which allows application in vivo • Replaces the coding sequences of the vector and replacing them with the desired new code.
TALEN “Transcription Activator-Like Effector Nucleases” Theory Applications Gene disruption Gene addition (Gaj, et al., 2013) • Naturally occurring protein from Xanthomonas • Repeats are linked to recognise DNA sequences
References Gaj, T., Gersbach, C. A. & Barbas III, C. F., 2013. ZFN, TALEN, and CRISPR/Cas-based methods for genome engineering. Trends in Biotechnology, 31(7), pp. 397-405. Hine, R. & Martin, E., 2015. A Dictionary of Biology. 7 ed. s.l.:Oxford University Press. Rey-Rico, A. & Cucchiarini, M., 2016. Controlled release strategies for rAAV-mediated gene delivery. ActaBiomaterialia, Volume 29, pp. 1-10. Singh, P., Schimenti, J. C. & Bolcun-Filas, E., 2015. A Mouse Geneticist’s Practical Guide to CRISPR Applications. GENETICS, 199(1), pp. 1-15. The He Lab, 2018. About Lulu and Nana: Twin Girls Born Healthy After Gene Surgery As Single-Cell Embryos. s.l.:s.n. • Merriam-Webster., 2018. Gene Editing. [Online] [Accessed 07 12 2018].