Abstract
Gene therapies for genetic diseases have been sought for decades, and the relatively recent development of the CRISPR/Cas9 gene-editing system has encouraged a new wave of interest in the field. There have nonetheless been significant setbacks to gene therapy, including unintended biological consequences, ethical scandals, and death. The major focus of research has been on technological problems such as delivery, potential immune responses, and both on and off-target effects in an effort to avoid negative clinical outcomes. While the field has concentrated on how we can better achieve gene therapies and gene editing techniques, there has been less focus on when and why we should use such technology. Here we combine discussion of both the technical and ethical barriers to the widespread clinical application of gene therapy and gene editing, providing a resource for gene therapy experts and novices alike. We discuss ethical problems and solutions, using cystic fibrosis and beta-thalassemia as case studies where gene therapy might be suitable, and provide examples of situations where human germline gene editing may be ethically permissible. Using such examples, we propose criteria to guide researchers and clinicians in deciding whether or not to pursue gene therapy as a treatment. Finally, we summarize how current progress in the field adheres to principles of biomedical ethics and highlight how this approach might fall short of ethical rigour using examples in the bioethics literature. Ultimately by addressing both the technical and ethical aspects of gene therapy and editing, new frameworks can be developed for the fair application of these potentially life-saving treatments.
Similar content being viewed by others
References
Acharya P, Lusvarghi S, Bewley CA, Kwong PD (2015) HIV-1 gp120 as a therapeutic target: navigating a moving labyrinth. Expert Opin Ther Targets. https://doi.org/10.1517/14728222.2015.1010513
Alapati D, Zacharias WJ, Hartman HA, Rossidis AC, Stratigis JD, Ahn NJ et al (2019) In utero gene editing for monogenic lung disease. Sci Transl Med. https://doi.org/10.1126/scitranslmed.aav8375
Albright C (2018) Discovery of EDIT-101 for the treatment of Leber’s congenital amaurosis type 10. Editas Medicine. https://www.editasmedicine.com/wp-content/uploads/2019/10/keystone_-_albright_-_jan_2018_1518202116.pdf. Accessed 20 Feb 2021
Al Idrus A (2021) |JPM: Verve Therapeutics unveils its lead program—a one-and-done treatment for genetic high cholesterol. FierceBiotech. https://www.fiercebiotech.com/biotech/jpm-verve-therapeutics-unveils-its-lead-program-a-one-and-done-treatment-for-genetic-high. Accessed 13 Jan 2021
Avery OT, MacLeod CM, McCarty M (1944) Studies on the chemical nature of the substance inducing transformation of pneumococcal types. J Exp Med. https://doi.org/10.1084/jem.79.2.137
Barrangou R, Fremaux C, Deveau H, Richards M, Boyaval P, Moineau S et al (2007) CRISPR provides acquired resistance against viruses in prokaryotes. Science. https://doi.org/10.1126/science.1138140
Baylis F (2016) “Broad societal consensus” on human germline editing. Harv Health Policy Rev 15(2):19–22. https://cdn.dal.ca/content/dam/dalhousie/pdf/sites/noveltechethics/nte-HHPRCRISPR_Baylis.pdf. Accessed 20 Feb 2021
Baylis F (2019) Before heritable genome editing, we need slow science and dialogue “within and across nations”. https://www.statnews.com/2019/09/23/genome-editing-slow-science-dialogue/. Accessed 10 Jan 2021
Baylis F, Darnovsky M (2019) Scientists disagree about the ethics and Governance of Human Germline Editing—The Hastings Center. https://www.thehastingscenter.org/scientists-disagree-ethics-governance-human-germline-genome-editing/. Accessed 10 Jan 2021
Baylis F, Kenny NP, Sherwin S (2008) A relational account of public health ethics. Public Health Ethics. https://doi.org/10.1093/phe/phn025
Baylis F, Getz LJ, Dellaire G (2018) Why we are not ready for genetically designed babies. https://theconversation.com/why-we-are-not-ready-for-genetically-designed-babies-107756. Accessed 10 Jan 2021
Baylis F, Darnovsky M, Hasson K, Krahn TM (2020) Human germline and heritable genome editing: the global policy landscape. CRISPR J. https://doi.org/10.1089/crispr.2020.0082
Beauchamp TL, Childress JF (2013) Principles of biomedical ethics, 7th edn. Oxford University Press, New York
Berg P, Singer MF (1995) The recombinant DNA controversy: twenty years later. Proc Natl Acad Sci. https://doi.org/10.1073/pnas.92.20.9011
Berg P, Baltimore D, Brenner S, Roblin RO, Singer MF (1975) Summary statement of the Asilomar conference on recombinant DNA molecules. Proc Natl Acad Sci. https://doi.org/10.1073/pnas.72.6.1981
Beutler E (2001) The cline affair. Mol Ther. https://doi.org/10.1006/mthe.2001.0486
Blaese RM, Culver KW, Miller AD, Carter CS, Fleisher T, Clerici M et al (1995) T lymphocyte-directed gene therapy for ADA-SCID: initial trial results after 4 years. Science 270(5235):475–480. https://doi.org/10.1126/science.270.5235.475
Brice P, Jarrett J, Mugford M (2007) Genetic screening for cystic fibrosis: an overview of the science and the economics. J Cyst Fibros. https://doi.org/10.1016/j.jcf.2007.02.002
Brock DJ (1996) Prenatal screening for cystic fibrosis: 5 years’ experience reviewed. Lancet. https://doi.org/10.1016/S0140-6736(96)90340-2
Broeders M, Herrero-Hernandez P, Ernst MPT, van der Ploeg AT, Pijnappel WWMP (2020) Sharpening the molecular scissors: advances in gene-editing technology. iScience 23(1):100789. https://doi.org/10.1016/j.isci.2019.100789
Brokowski C, Adli M (2019) CRISPR ethics: moral considerations for applications of a powerful tool. J Mol Biol 431(1):88–101. https://doi.org/10.1016/j.jmb.2018.05.044
Caplan A (2018) He Jiankui’s moral mess—PLOS biologue. https://biologue.plos.org/2018/12/03/he-jiankuis-moral-mess/. Accessed 11 Jan 2021
Carreras A, Pane LS, Nitsch R, Madeyski-Bengtson K, Porritt M, Akcakaya P et al (2019) In vivo genome and base editing of a human PCSK9 knock-in hypercholesterolemic mouse model. BMC Biol 17(1):4. https://doi.org/10.1186/s12915-018-0624-2
Castellani C, Macek M, Cassiman J-J, Duff A, Massie J, ten Kate LP et al (2010) Benchmarks for cystic fibrosis carrier screening: a European consensus document. J Cyst Fibros. https://doi.org/10.1016/j.jcf.2010.02.005
Chang KH, Smith SE, Sullivan T, Chen K, Zhou Q, West JA et al (2017) Long-term engraftment and fetal globin induction upon BCL11A gene editing in bone-marrow-derived CD34+ hematopoietic stem and progenitor cells. Mol Ther Methods Clin Dev 4(March):137–148. https://doi.org/10.1016/j.omtm.2016.12.009
Chase L (2020) 10 Most expensive drugs in the U.S., period. https://www.goodrx.com/blog/most-expensive-drugs-period/. Accessed 11 Jan 2021
Christian M, Cermak T, Doyle EL, Schmidt C, Zhang F, Hummel A et al (2010) Targeting DNA double-strand breaks with TAL effector nucleases. Genetics 186(2):756–761. https://doi.org/10.1534/genetics.110.120717
Cohen J (2019) Did CRISPR help—or harm—the first-ever gene-edited babies? Science. https://doi.org/10.1126/science.aay9569
Cohen J (2020) CRISPR, the revolutionary genetic ‘scissors’, honored by Chemistry Nobel. Science. https://doi.org/10.1126/science.abf0540
Colah R, Gorakshakar A, Nadkarni A (2010) Global burden, distribution and prevention of β-thalassemias and hemoglobin E disorders. Expert Rev Hematol. https://doi.org/10.1586/ehm.09.74
Conboy I, Murthy N, Etienne J, Robinson Z (2018) Making gene editing a therapeutic reality [version 1; referees: 2 approved]. F1000Research 7(0):1–10. https://doi.org/10.12688/f1000research.16106.1
Crowe K (2018) The million-dollar drug|CBC News https://newsinteractives.cbc.ca/longform/glybera. Accessed 11 Jan 2021
Crowe K (2019) Canadian breakthrough that became the world’s most expensive drug, then vanished, gets second chance|CBC News. https://www.cbc.ca/news/health/glybera-lpld-rare-drug-orphan-disease-nrc-cbc-price-1.5312177. Accessed 11 Jan 2021
Cunningham S, Marshall T (1998) Influence of five years of antenatal screening on the paediatric cystic fibrosis population in one region. Arch Dis Child. https://doi.org/10.1136/adc.78.4.345
Cyranoski D (2019) China to tighten rules on gene editing in humans. Nature. https://doi.org/10.1038/d41586-019-00773-y
Cyranoski D (2020) Russian biologist plans more CRISPR-edited babies. Nature. https://doi.org/10.1038/d41586-019-01770-x
Cystic Fibrosis Foundation (2021a) CFTR modulator therapies. https://www.cff.org/Life-With-CF/Treatments-and-Therapies/Medications/CFTR-Modulator-Therapies/. Accessed 11 Jan 2021
Cystic Fibrosis Foundation (2021b) CFTR modulator types. https://www.cff.org/Research/Developing-New-Treatments/CFTR-Modulator-Types/. Accessed 11 Jan 2021
Cystic Fibrosis Foundation (2021c) Clinical trials finder|CFF clinical trials tool. https://www.cff.org/trials/finder. Accessed 11 Jan 2021
de Oliveira CEC, Oda JMM, Losi Guembarovski R, de Oliveira KB, Ariza CB, Neto JS et al (2014) CC chemokine receptor 5: the interface of host immunity and cancer. Dis Markers. https://doi.org/10.1155/2014/126954
Dellaire G (2018) Editorial: CRISPR medicine: from bench to bedside. Curr Gene Ther 17(4):261–262. https://doi.org/10.2174/156652321704180104153508
Dhooge PPA, Valkenburg D, Hoyng CB (2020) Gene therapy for inherited retinal diseases. In: Gao XR (ed) Genetics and genomics of eye disease. Academic Press, pp 279–295. https://doi.org/10.1016/B978-0-12-816222-4.00017-4
Dickson D (1981) Cline stripped of research grants. Nature. https://doi.org/10.1038/294391b0
Doench JG, Hartenian E, Graham DB, Tothova Z, Hegde M, Smith I et al (2014) Rational design of highly active sgRNAs for CRISPR-Cas9–mediated gene inactivation. Nat Biotechnol. https://doi.org/10.1038/nbt.3026
Dzau VJ, McNutt M, Bai C (2018) Wake-up call from Hong Kong. Science. https://doi.org/10.1126/science.aaw3127
Editorial (2018) How to respond to CRISPR babies. Nature. https://doi.org/10.1038/d41586-018-07634-0
Foil KE, Powers A, Raraigh KS, Wallis K, Southern KW, Salinas D (2019) The increasing challenge of genetic counseling for cystic fibrosis. J Cyst Fibros. https://doi.org/10.1016/j.jcf.2018.11.014
Friesen P, Kearns L, Redman B, Caplan AL (2017) Rethinking the Belmont report? Am J Bioeth. https://doi.org/10.1080/15265161.2017.1329482
Garneau JE, Dupuis M-È, Villion M, Romero DA, Barrangou R, Boyaval P et al (2010) The CRISPR/Cas bacterial immune system cleaves bacteriophage and plasmid DNA. Nature. https://doi.org/10.1038/nature09523
Gaudelli NM, Komor AC, Rees HA, Packer MS, Badran AH, Bryson DI, Liu DR (2017) Programmable base editing of A•T to G•C in genomic DNA without DNA cleavage. Nature. https://doi.org/10.1038/nature24644
Getz LJ, Dellaire G (2018) Angels and devils: dilemmas in dual-use biotechnology. Trends Biotechnol 36(12):1202–1205. https://doi.org/10.1016/j.tibtech.2018.07.016
Getz LJ, Dellaire G (2020) Back to basics: application of the principles of bioethics to heritable genome interventions. Sci Eng Ethics 26(5):2735–2748. https://doi.org/10.1007/s11948-020-00226-0
Geurts MH, de Poel E, Amatngalim GD, Oka R, Meijers FM, Kruisselbrink E et al (2020) CRISPR-based adenine editors correct nonsense mutations in a cystic fibrosis organoid biobank. Cell Stem Cell. https://doi.org/10.1016/j.stem.2020.01.019
Griffith F (1928) The significance of pneumococcal types. J Hyg. https://doi.org/10.1017/S0022172400031879
Gu W-G, Chen X-Q (2014) Targeting CCR5 for anti-HIV research. Eur J Clin Microbiol Infect Dis. https://doi.org/10.1007/s10096-014-2173-0
Hashimoto M, Yamashita Y, Takemoto T (2016) Electroporation of Cas9 protein/sgRNA into early pronuclear zygotes generates non-mosaic mutants in the mouse. Dev Biol 418(1):1–9. https://doi.org/10.1016/j.ydbio.2016.07.017
Hewes AM, Sansbury BM, Barth S, Tarcic G, Kmiec EB (2020) gRNA sequence heterology tolerance catalyzed by CRISPR/Cas in an in vitro homology-directed repair reaction. Mol Ther Nucleic Acids. https://doi.org/10.1016/j.omtn.2020.03.012
Hong SG, Yada RC, Choi K, Carpentier A, Liang TJ, Merling RK et al (2017) Rhesus iPSC safe harbor gene-editing platform for stable expression of transgenes in differentiated cells of all germ layers. Mol Ther 25(1):44–53. https://doi.org/10.1016/j.ymthe.2016.10.007
Hsu PD, Scott DA, Weinstein JA, Ran FA, Konermann S, Agarwala V et al (2013) DNA targeting specificity of RNA-guided Cas9 nucleases. Nat Biotechnol. https://doi.org/10.1038/nbt.2647
Huai C, Jia C, Sun R, Xu P, Min T, Wang Q et al (2017) CRISPR/Cas9-mediated somatic and germline gene correction to restore hemostasis in hemophilia B mice. Hum Genet 136(7):875–883. https://doi.org/10.1007/s00439-017-1801-z
Hurlbut JB, Saha K, Jasanoff S (2015) CRISPR democracy: gene editing and the need for inclusive deliberation|issues in science and technology. Issues Sci Technol 32(1). https://issues.org/crispr-democracy-gene-editing-and-the-need-for-inclusive-deliberation/. Accessed 20 Feb 2021
International Bioethics Committee (1998) Universal declaration on the human genome and human rights. https://en.unesco.org/themes/ethics-science-and-technology/human-genome-and-human-rights. Accessed 20 Feb 2021
International Bioethics Committee (2015) Report of the IBC on updating its reflection on the human genome and human rights. https://unesdoc.unesco.org/ark:/48223/pf0000233258. Accessed 20 Feb 2021
Irion S, Luche H, Gadue P, Fehling HJ, Kennedy M, Keller G (2007) Identification and targeting of the ROSA26 locus in human embryonic stem cells. Nat Biotechnol. https://doi.org/10.1038/nbt1362
Jasin M, Haber JE (2016) The democratization of gene editing: insights from site-specific cleavage and double-strand break repair. DNA Repair. https://doi.org/10.1016/j.dnarep.2016.05.001
Jiang T, Henderson JM, Coote K, Cheng Y, Valley HC, Zhang X-O et al (2020) Chemical modifications of adenine base editor mRNA and guide RNA expand its application scope. Nat Commun. https://doi.org/10.1038/s41467-020-15892-8
Jiankui H, Ferrell R, Yuanlin C, Jinzhou Q, Yangran C (2018) Draft ethical principles for therapeutic assisted reproductive technologies. CRISPR J. https://doi.org/10.1089/crispr.2018.0051
Jinek M, Chylinski K, Fonfara I, Hauer M, Doudna JA, Charpentier E (2012) A programmable dual-RNA-guided DNA endonuclease in adaptive bacterial immunity. Science. https://doi.org/10.1126/science.1225829
Kessels SJM, Carter D, Ellery B, Newton S, Merlin TL (2020) Prenatal genetic testing for cystic fibrosis: a systematic review of clinical effectiveness and an ethics review. Genet Med. https://doi.org/10.1038/s41436-019-0641-8
Khamsi R (2020) Gene therapy could offer an inclusive cure for cystic fibrosis. Nature 583(7818):S12–S14. https://doi.org/10.1038/d41586-020-02111-z
Kim YG, Cha J, Chandrasegaran S (1996) Hybrid restriction enzymes: zinc finger fusions to Fok I cleavage domain. Proc Natl Acad Sci USA 93(3):1156–1160. https://doi.org/10.1073/pnas.93.3.1156
Kirubarajan A, Norris E, Oliveria J-P (2017) It’s in your genes: recent considerations in germline versus somatic gene therapy. Health Sci Inq 8(1):47–49. https://doi.org/10.29173/hsi238
Klug A (2010) The discovery of zinc fingers and their development for practical applications in gene regulation and genome manipulation. Q Rev Biophys 43(1):1–21. https://doi.org/10.1017/S0033583510000089
Koblan LW, Erdos MR, Wilson C, Cabral WA, Levy JM, Xiong ZM et al (2021) In vivo base editing rescues Hutchinson-Gilford progeria syndrome in mice. Nature. https://doi.org/10.1038/s41586-020-03086-7
LaManna CM, Pyhtila B, Barrangou R (2020) Sharing the CRISPR toolbox with an expanding community. CRISPR J. https://doi.org/10.1089/crispr.2020.0075
Lee M, Kim H (2019) Therapeutic application of the CRISPR system: current issues and new prospects. Hum Genet 138(6):563–590. https://doi.org/10.1007/s00439-019-02028-2
Lee S-J, Lehar A, Meir JU, Koch C, Morgan A, Warren LE et al (2020) Targeting myostatin/activin A protects against skeletal muscle and bone loss during spaceflight. Proc Natl Acad Sci. https://doi.org/10.1073/pnas.2014716117
Leibowitz M, Papathanasiou S, Doerfler P, Blaine L, Yao Y, Zhang C-Z et al (2020) Chromothripsis as an on-target consequence of CRISPR-Cas9 genome editing. BioRxiv, 2020.07.13.200998. https://doi.org/10.1101/2020.07.13.200998
Li L, Krymskaya L, Wang J, Henley J, Rao A, Cao L-F et al (2013) Genomic editing of the HIV-1 coreceptor CCR5 in adult hematopoietic stem and progenitor cells using zinc finger nucleases. Mol Ther. https://doi.org/10.1038/mt.2013.65
Li S, Wehrenberg B, Waldman BC, Waldman AS (2018) Mismatch tolerance during homologous recombination in mammalian cells. DNA Repair 70:25–36. https://doi.org/10.1016/j.dnarep.2018.07.011
Maeder ML, Stefanidakis M, Wilson CJ, Baral R, Barrera LA, Bounoutas GS et al (2019) Development of a gene-editing approach to restore vision loss in Leber congenital amaurosis type 10. Nat Med. https://doi.org/10.1038/s41591-018-0327-9
Marx V (2018) Base editing a CRISPR way. Nat Methods 15(10):767–770. https://doi.org/10.1038/s41592-018-0146-4
Maule G, Arosio D, Cereseto A (2020) Gene therapy for cystic fibrosis: progress and challenges of genome editing. Int J Mol Sci. https://doi.org/10.3390/ijms21113903
McConaghie A (2017) Glybera, the most expensive drug in the world, to be withdrawn after commercial flop. https://pharmaphorum.com/news/glybera-expensive-drug-world-withdrawn-commercial-flop/. Accessed 11 Jan 2021
McLeod C, Sherwin S (2000) Relational autonomy, self-trust, and health care for patients who are oppressed. Relational autonomy: feminist perspectives on autonomy, agency and the social self. https://ir.lib.uwo.ca/philosophypub/345. Accessed 13 Jan 2021
Meagher KM, Allyse MA, Master Z, Sharp RR (2020) Reexamining the ethics of human germline editing in the wake of scandal. Mayo Clin Proc 95(2):330–338. https://doi.org/10.1016/j.mayocp.2019.11.018
Mehravar M, Shirazi A, Nazari M, Banan M (2019) Mosaicism in CRISPR/Cas9-mediated genome editing. Dev Biol 445(2):156–162. https://doi.org/10.1016/j.ydbio.2018.10.008
Mekler V, Minakhin L, Semenova E, Kuznedelov K, Severinov K (2016) Kinetics of the CRISPR-Cas9 effector complex assembly and the role of 3′-terminal segment of guide RNA. Nucleic Acids Res 44(6):2837–2845. https://doi.org/10.1093/nar/gkw138
Melim C, Jarak I, Veiga F, Figueiras A (2020) The potential of micelleplexes as a therapeutic strategy for osteosarcoma disease. 3 Biotech. https://doi.org/10.1007/s13205-020-2142-5
Miller JC, Tan S, Qiao G, Barlow KA, Wang J, Xia DF et al (2011) A TALE nuclease architecture for efficient genome editing. Nat Biotechnol 29(2):143–150. https://doi.org/10.1038/nbt.1755
Moehle EA, Rock JM, Lee YL, Jouvenot Y, DeKelver RC, Gregory PD et al (2007) Targeted gene addition into a specified location in the human genome using designed zinc finger nucleases. Proc Natl Acad Sci USA 104(9):3055–3060. https://doi.org/10.1073/pnas.0611478104
Mojica FJM, Diez-Villasenor C, Soria E, Juez G (2000) Biological significance of a family of regularly spaced repeats in the genomes of archaea, bacteria and mitochondria. Mol Microbiol. https://doi.org/10.1046/j.1365-2958.2000.01838.x
Nakade S, Tsubota T, Sakane Y, Kume S, Sakamoto N, Obara M et al (2014) Microhomology-mediated end-joining-dependent integration of donor DNA in cells and animals using TALENs and CRISPR/Cas9. Nat Commun. https://doi.org/10.1038/ncomms6560
National Academies of Sciences Engineering and Medicine (2015) International summit on human gene editing. In: Olson S (ed) National Academies Press, Washington, DC. https://doi.org/10.17226/21913
National Academies of Sciences Engineering and Medicine (2017) Human genome editing. National Academies Press, Washington, DC. https://doi.org/10.17226/24623
National Academies of Sciences Engineering and Medicine (2019) Second international summit on human genome editing: continuing the global discussion. In: Olson S (ed) National Academies Press, Washington, DC. https://doi.org/10.17226/25343
Nelson HH, Sweetser DB, Nickoloff JA (1996) Effects of terminal nonhomology and homeology on double-strand-break-induced gene conversion tract directionality. Mol Cell Biol 16(6):2951–2957. https://doi.org/10.1128/mcb.16.6.2951
Nuffield Council on Bioethics (2018) Genome editing and human reproduction: social and ethical issues. https://www.nuffieldbioethics.org/publications/genome-editing-and-human-reproduction. Accessed 10 Jan 2021
Nuffield Council on Bioethics, Shakespeare T, Bryant L, Clancy T, Clarke A, Deans Z et al (2017) Non-invasive prenatal testing: ethical issues
Orthwein A, Noordermeer SM, Wilson MD, Landry S, Enchev RI, Sherker A et al (2015) A mechanism for the suppression of homologous recombination in G1 cells. Nature 528(7582):422–426
Parens E, Asch A (2003) Disability rights critique of prenatal genetic testing: reflections and recommendations. Ment Retard Dev Disabil Res Rev 9(1):40–47. https://doi.org/10.1002/mrdd.10056
Patel A, Zhao J, Duan D, Lai Y (2019) Design of AAV vectors for delivery of large or multiple transgenes. In: Castle MJ (ed) Methods in molecular biology, vol 1950. Springer Nature, pp 19–33. https://doi.org/10.1007/978-1-4939-9139-6_2
Paulk N (2020) Gene therapy: it’s time to talk about high-dose AAV. Genetic Engineering & Biotechnology News. https://www.genengnews.com/commentary/gene-therapy-its-time-to-talk-about-high-dose-aav/. Accessed 20 Feb 2021
Pellenz S, Phelps M, Tang W, Hovde BT, Sinit RB, Fu W et al (2019) New human chromosomal sites with “safe harbor” potential for targeted transgene insertion. Hum Gene Ther 30(7):814–828. https://doi.org/10.1089/hum.2018.169
Pinder J, Salsman J, Dellaire G (2015) Nuclear domain “knock-in” screen for the evaluation and identification of small molecule enhancers of CRISPR-based genome editing. Nucleic Acids Res 43(19):9379–9392. https://doi.org/10.1093/nar/gkv993
Prakash V, Moore M, Yáñez-Muñoz RJ (2016) Current progress in therapeutic gene editing for monogenic diseases. Mol Ther. https://doi.org/10.1038/mt.2016.5
Ramirez VB (2019) First human CRISPR trial in the US aims to cure inherited blindness. https://singularityhub.com/2019/07/28/first-human-crispr-trial-in-the-us-aims-to-cure-inherited-blindness/. Accessed 11 Jan 2021
Rhodes R (2019) Why not common morality? J Med Ethics. https://doi.org/10.1136/medethics-2019-105621
Rodrigues GA, Shalaev E, Karami TK, Cunningham J, Slater NKH, Rivers HM (2019) Pharmaceutical development of AAV-based gene therapy products for the eye. Pharm Res. https://doi.org/10.1007/s11095-018-2554-7
Rothkamm K, Krüger I, Thompson LH, Löbrich M (2003) Pathways of DNA double-strand break repair during the mammalian cell cycle. Mol Cell Biol. https://doi.org/10.1128/MCB.23.16.5706-5715.2003
Roy B, Zhao J, Yang C, Luo W, Xiong T, Li Y et al (2018) CRISPR/cascade 9-mediated genome editing-challenges and opportunities. Front Genet 9(JUL):1–12. https://doi.org/10.3389/fgene.2018.00240
Salsman J, Dellaire G (2017) Precision genome editing in the CRISPR era. Biochem Cell Biol 95(2):187–201. https://doi.org/10.1139/bcb-2016-0137
Salsman J, Masson J-Y, Orthwein A, Dellaire G (2017) CRISPR/Cas9 gene editing: from basic mechanisms to improved strategies for enhanced genome engineering in vivo. Curr Gene Ther. https://doi.org/10.2174/1566523217666171122094629
Sandoval IM, Collier TJ, Manfredsson FP (2019) Design and assembly of CRISPR/Cas9 lentiviral and rAAV vectors for targeted genome editing. In: Manfredsson FP, Benskey MJ (eds) Methods in molecular biology, vol 1937. Springer Nature, Clifton, pp 29–45
Sanjurjo-Soriano C, Kalatzis V (2018) Guiding lights in genome editing for inherited retinal disorders: implications for gene and cell therapy. Neural Plast 2018:5056279. https://doi.org/10.1155/2018/5056279
Schwank G, Koo BK, Sasselli V, Dekkers JF, Heo I, Demircan T et al (2013) Functional repair of CFTR by CRISPR/Cas9 in intestinal stem cell organoids of cystic fibrosis patients. Cell Stem Cell 13(6):653–658. https://doi.org/10.1016/j.stem.2013.11.002
Shreenivas S (2000) Who killed Jesse Gelsinger? Ethical issues in human gene therapy. Monash Bioeth Rev 19(3):35–43. https://doi.org/10.1007/bf03351239
Sibbald B (2001) Death but one unintended consequence of gene-therapy trial. CMAJ 164(11). https://www.cmaj.ca/content/164/11/1612. Accessed 20 Feb 2021
Singh JK, van Attikum H (2020) DNA double-strand break repair: putting zinc fingers on the sore spot. Semin Cell Dev Biol. https://doi.org/10.1016/j.semcdb.2020.09.003
Stanojevic S, Vukovojac K, Sykes J, Ratjen F, Tullis E, Stephenson AL (2020) Projecting the impact of delayed access to elexacaftor/tezacaftor/ivacaftor for people with Cystic Fibrosis. J Cyst Fibros. https://doi.org/10.1016/j.jcf.2020.07.017
Stolberg SG (1999) The biotech death of Jesse Gelsinger—The New York Times. https://www.nytimes.com/1999/11/28/magazine/the-biotech-death-of-jesse-gelsinger.html. Accessed 10 Jan 2021
Styer KL, Click EM, Hopkins GW, Frothingham R, Aballay A (2007) Study of the role of CCR5 in a mouse model of intranasal challenge with Yersinia pestis. Microbes Infect. https://doi.org/10.1016/j.micinf.2007.04.012
Sun M (1981) Cline loses two NIH grants. Science. https://doi.org/10.1126/science.7302590
Suzuki K, Tsunekawa Y, Hernandez-Benitez R, Wu J, Zhu J, Kim EJ et al (2016) In vivo genome editing via CRISPR/Cas9 mediated homology-independent targeted integration. Nature. https://doi.org/10.1038/nature20565
Tatum EL (1966) Molecular biology, nucleic acids, and the future of medicine. Perspect Biol Med. https://doi.org/10.1353/pbm.1966.0027
Teboul L, Herault Y, Wells S, Qasim W, Pavlovic G (2020) Variability in genome editing outcomes: challenges for research reproducibility and clinical safety. Mol Ther 28(6):1422–1431. https://doi.org/10.1016/j.ymthe.2020.03.015
Terheggen HG, Lowenthal A, Lavinha F, Colombo JP (1975) Familial hyperargininaemia. Arch Dis Child. https://doi.org/10.1136/adc.50.1.57
The National Academy of Sciences (2020) Heritable human genome editing. Heritable human genome editing. The National Academies Press, Washington, DC. https://doi.org/10.17226/25665
Trapani I, Auricchio A (2018) Seeing the light after 25 years of retinal gene t. Trends Mol Med 24(8):669–681. https://doi.org/10.1016/j.molmed.2018.06.006
Tu Z, Yang W, Yan S, Yin A, Gao J, Liu X et al (2017) Promoting Cas9 degradation reduces mosaic mutations in non-human primate embryos. Sci Rep 7(August 2016):1–11. https://doi.org/10.1038/srep42081
Vaidyanathan S, Salahudeen AA, Sellers ZM, Bravo DT, Choi SS, Batish A et al (2020) High-efficiency, selection-free gene repair in airway stem cells from cystic fibrosis patients rescues CFTR function in differentiated epithelia. Cell Stem Cell. https://doi.org/10.1016/j.stem.2019.11.002
Veit G, Roldan A, Hancock MA, Da Fonte DF, Xu H, Hussein M et al (2020) Allosteric folding correction of F508del and rare CFTR mutants by elexacaftor-tezacaftor-ivacaftor (Trikafta) combination. JCI Insight. https://doi.org/10.1172/jci.insight.139983
Viprakasit V, Ekwattanakit S (2018) Clinical classification, screening and diagnosis for thalassemia. Hematol/Oncol Clin N Am. https://doi.org/10.1016/j.hoc.2017.11.006
Wang D, Tai PWL, Gao G (2019) Adeno-associated virus vector as a platform for gene therapy delivery. Nat Rev Drug Discovery 18(5):358–378. https://doi.org/10.1038/s41573-019-0012-9
Ward P, Walsh CE (2012) Targeted integration of a rAAV vector into the AAVS1 region. Virology. https://doi.org/10.1016/j.virol.2012.08.015
Weijer C (1999) Protecting communities in research: philosophical and pragmatic challenges. Camb Q Healthc Ethics. https://doi.org/10.1017/S0963180199004120
Whitford CM, Lübke N-C, Rückert C (2018) Synthetic biology ethics at iGEM: iGEMer perspectives. Trends Biotechnol. https://doi.org/10.1016/j.tibtech.2018.06.004
Wirth T, Parker N, Ylä-Herttuala S (2013) History of gene therapy. Gene 525:162–169. https://doi.org/10.1016/j.gene.2013.03.137
Xue K, Groppe M, Salvetti AP, MacLaren RE (2017) Technique of retinal gene therapy: delivery of viral vector into the subretinal space. Eye (Basingstoke) 31(9):1308–1316. https://doi.org/10.1038/eye.2017.158
Yeh CD, Richardson CD, Corn JE (2019) Advances in genome editing through control of DNA repair pathways. Nat Cell Biol 21(12):1468–1478. https://doi.org/10.1038/s41556-019-0425-z
Zhang X, Chen L, Zhu B, Wang L, Chen C, Hong M et al (2020) Increasing the efficiency and targeting range of cytidine base editors through fusion of a single-stranded DNA-binding protein domain. Nat Cell Biol 22(6):740–750. https://doi.org/10.1038/s41556-020-0518-8
Zinder ND, Lederberg J (1952) Genetic exchange in Salmonella. J Bacteriol 64(5):679–699. https://doi.org/10.1128/JB.64.5.679-699.1952
Zipkin M (2019) CRISPR’s “magnificent moment” in the clinic. Nat Biotechnol. https://doi.org/10.1038/d41587-019-00035-2
Acknowledgements
We gratefully acknowledge feedback during the preparation of this review from Sabateeshan Mathavarajah and Dr. Françoise Baylis.
Funding
K.K. is a trainee of the Cancer Research Training Program of the Beatrice Hunter Cancer Research Institute, with funds provided by the Dalhousie Medical Research Foundation (DMRF) C. MacDougall Cancer Research Studentship, as well as being supported by a Genomics in Medicine Graduate Studentship from the Dalhousie Faculty of Medicine –DMRF and a Nova Scotia Scholar Award. L.J.G. is funded by a Vanier Canadian Graduate Scholarship from the Natural Science and Engineering Research Council of Canada (NSERC) as well as a Killam Pre-Doctoral Scholarship from the Killam Trusts. J-Y.M. is a Canada Research Chair in DNA repair and Cancer Therapeutics. This work is also supported by a Canadian Institutes of Health Research (CIHR) Project Grant (PJT-156017) to J-Y.M. and G.D.
Ethics declarations
Conflict of interest
The authors have no conflicts to declare.
Additional information
Publisher's Note
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Rights and permissions
About this article
Cite this article
Kratzer, K., Getz, L.J., Peterlini, T. et al. Addressing the dark matter of gene therapy: technical and ethical barriers to clinical application. Hum Genet 141, 1175–1193 (2022). https://doi.org/10.1007/s00439-021-02272-5
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s00439-021-02272-5