Heritable human genome editing: Research progress, ethical considerations, and hurdles to clinical practice
نویسندگان
چکیده
Our genome at conception determines much of our health as an adult. Most human diseases have a heritable component and thus may be preventable through editing. Preventing disease from the beginning life before irreversible damage has occurred is admirable goal, but path to fruition remains unclear. Here, we review significant scientific contributions field editing, unique ethical challenges that cannot overlooked, hurdles must overcome prior translating these technologies into clinical practice. The introduction editing using clustered regularly interspaced short palindromic repeats (CRISPR)-based generated tremendous enthusiasm well controversy within medical public communities. Heritable Human Genome Editing (HHGE) potential treat or even eradicate genetic diseases. By addressing defect amplified cell proliferation during development, HHGE prove more effective than any other treatment being developed today, including somatic gene drug therapy (Figure 1). Somatic therapies are limited in their ability reverse already reach billions cells needed adequately disease. brief vitro culture embryo routinely practiced IVF clinics provides readily accessible window for prevention numerous conditions later difficult manage, let alone cure. This hope rationale research, not yet therapy, criteria efficacy safety met. also raises regulatory questions. Manipulations early highly consequential, both with regard benefits risks. Other reviews discussed emphasizing its understanding function (Lea Niakan, 2019Lea R.A. Niakan K. germline editing.Nat. Cell Biol. 2019; 21: 1479-1489Crossref PubMed Scopus (20) Google Scholar; Rossant, 2018Rossant J. Gene development: concerns practical applications.Development. 2018; 145: dev150888Crossref (16) Plaza Reyes Lanner, 2017Plaza A. Lanner F. Towards CRISPR view applications, limitations embryos.Development. 2017; 144: 3-7Crossref (27) Scholar). summarize research on therapeutic value, implications, new risks were identified recent studies. Studies since 1980s demonstrated power DNA double-stand breaks (DSBs) targeted change, first yeast then mammalian (reviewed by Jasin Rothstein, 2013Jasin M. Rothstein R. Repair strand homologous recombination.Cold Spring Harb. Perspect. 2013; 5: a012740Crossref (491) DSBs occur replication process, after exposure ionizing radiation chemotherapy, experimental manipulation repaired mainly one two repair pathways: nonhomologous end joining (NHEJ) homology directed (HDR). Based pioneering studies model organisms, it became evident induction DSB ideal approach correction disease-causing mutations. A critical breakthrough was discovery sequence specific nucleases amenable design. Engineered can target create position. During original vicinity cut altered, creating sequence. Several biological systems types such transcription activator-like effector (TALENs) zinc finger (ZFNs) provide capabilities double-stranded DNA. Both TALENs ZFNs consist combination repetitive protein segments, each binding specificity 1 3 nucleotides, generate domain single site genome. However, RNA-guided made changes scalable wide range applications. Shortly endonuclease CRISPR-Cas9 described (Gasiunas et al., 2012Gasiunas G. Barrangou Horvath P. Siksnys V. Cas9-crRNA ribonucleoprotein complex mediates cleavage adaptive immunity bacteria.Proc. Natl. Acad. Sci. USA. 2012; 109: E2579-E2586Crossref (1436) Jinek 2012Jinek Chylinski Fonfara I. Hauer Doudna J.A. Charpentier E. programmable dual-RNA-guided bacterial immunity.Science. 337: 816-821Crossref (7874) Scholar), adapted modifying cultured (Cong 2013Cong L. Ran F.A. Cox D. Lin S. Barretto Habib N. Hsu P.D. Wu X. Jiang W. Marraffini L.A. Zhang Multiplex engineering CRISPR/Cas systems.Science. 339: 819-823Crossref (8856) Mali 2013Mali Yang Esvelt K.M. Aach Guell DiCarlo J.E. Norville Church G.M. via Cas9.Science. 823-826Crossref (5800) Scholar) followed embryos (Liang 2015Liang Xu Y. Ding C. Huang Z. Lv Xie Chen Li al.CRISPR/Cas9-mediated tripronuclear zygotes.Protein Cell. 2015; 6: 363-372Crossref (691) Kang 2016Kang He Yu Q. Gao Sun Fan Introducing precise modifications 3PN CRISPR/Cas-mediated editing.J. Assist. Reprod. Genet. 2016; 33: 581-588Crossref (183) Tang 2017Tang Zeng Du H. Gong Peng B. Lei Zhao Wang Liu CRISPR/Cas9-mediated zygotes Cas9 protein.Mol. Genomics. 292: 525-533Crossref (130) reviewed Lea Scholar. Initial CRISPR-Cas9-mediated focused rates mutation correction, off-target edits, mosaicism—multiple different outcomes same 2). study use non-viable (3PN) embryos. While this took advantage would clinically discarded, developmental karyotypes interpret hence evaluated. After injecting CRISPR-Cas9, Liang colleagues found only 4 71 (5.6%) contained desired change hemoglobin ? (HBB) correctly edited mosaic mutations common acting sites injected 126 mRNA, guide RNA (gRNA), template modify immune CCR5 (Kang Genetic analysis showed 2 successfully modified intended 32 bp deletion. gRNAs delete segment without need HDR successful 4/26 Embryos mosaic. Also embryos, al. integration 2/30 (6.6%) G6PD locus, 14% (2/14) HBB locus (Tang Using diploid 2PN fertilized mutant sperm, Scholar could corrected. All told, however, low number all which proved Another targeting MYBPC3, causes hypertrophic cardiomyopathy, reported efficiency embryos; out 58 some (Ma 2017Ma Marti-Gutierrez Park S.W. Lee Suzuki Koski Ji Hayama T. Ahmed al.Correction pathogenic embryos.Nature. 548: 413-419Crossref (533) As sperm donor used heterozygous, estimated 29 resulting ?3%. For therapeutically relevant will increased. Low due lack control over when cell-cycle phase. active S G2 phases G1, though assertion been directly tested Furthermore, timing kinetics determined. Timing microinjection phase cycle useful promoting mouse (Gu 2018Gu Posfai Rossant Efficient generation large insertions two-cell-stage embryos.Nat. Biotechnol. 36: 632-637Crossref (113) According Gu Scholar, further increased 95% tethering biotinylated Cas9, fusion monomeric avidin. appears promising. In embryonic stem cells, recombination ?2-fold interference 53BP1 (Nambiar 2019Nambiar T.S. Billon Diedenhofen Hayward S.B. Taglialatela Cai J.W. Leuzzi Cuella-Martin Palacios al.Stimulation CRISPR-mediated homology-directed engineered RAD18 variant.Nat. Commun. 10: 3395Crossref (39) Canny 2018Canny M.D. Moatti Wan L.C.K. Fradet-Turcotte Krasner Mateos-Gomez P.A. 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Ommundsen overexpression double-strand break pathways instability.Oncogene. 2004; 23: 546-553Crossref (182) Neither far groups introduce programmed edits Ma restore disrupt function. generally novel alleles no precedent population. instance, recurrent end-joining events reading frame EYS results altered amino acid relative wild type (Zuccaro 2020Zuccaro M.V. Mitchell Marin Zimmerman Rana Weinstein King R.T. Palmerola K.L. Smith M.E. al.Allele-Specific Chromosome Removal Cleavage Embryos.Cell. 2020; 183: 1650-1664Abstract (53) very context, product development. identify requirement POU5F1 normal blastocyst development (Fogarty 2017Fogarty N.M.E. McCarthy Snijders K.E. Powell B.E. Kubikova Blakeley Elder Wamaitha S.E. Kim al.Genome reveals role OCT4 embryogenesis.Nature. 550: 67-73Crossref (194) context reproduction, functional testing allele possible, acceptable, therefore person known. report Royal Society National Academies Sciences, Engineering, Medicine specifically called variants population correct (NAS, Academy Medicine, Sciences Society, 2020NAS, SocietyHeritable Editing. Press, 2020Google Thus, preferable correction. studies; aggregate, less 10% modification. formation indels predominates about 10-fold addition small recombination, Cas9-induced extensive changes. gave rise deletions several hundred base pairs almost half (Adikusuma 2018Adikusuma Piltz Corbett M.A. Turvey McColl S.R. Helbig K.J. Beard M.R. Hughes Pomerantz Thomas P.Q. Large induced cleavage.Nature. 560: E8-E9Crossref (101) Such (Kosicki 2018Kosicki Tomberg Bradley leads rearrangements.Nat. 765-771Crossref (45) Kosicki 20% >250 extending up 6 kb away site. 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(2020.07.13.200998)Google cells. body work better understand endogenous machinery outcomes. primary limitation gene-editing approaches prevent mosaicism. restricting activity editors cycle, potentially advance mosaicism avoided. anti-CRISPR proteins (Pawluk 2018Pawluk Davidson A.R. Maxwell Anti-CRISPR: discovery, mechanism function.Nat. Rev. Microbiol. 16: 12-17Crossref (163) enable temporal timed injection Cas9. Interestingly, delay majority most cycles delayed anti-Crispr AcrIIA4 while still allowing (Shin 2017Shin J.-J. Bray N.L. Rauch B.J. Baik S.H. Nogales Bondy-Denomy Corn Disabling mimic.Sci. Adv. 3: e1701620Crossref (177) Anti-Crispr promise reduce Recently prime avoid aforementioned undesirable catalytically inactive serves deaminase mediate site-specific nucleotide conversions (Komor 2016Komor A.C. Y.B. Packer M.S. Zuris D.R. Programmable 533: 420-424Crossref (1843) Base (Zhou 2017Zhou Wei Pan Zhong al.Highly efficient 8: 772-775Crossref (40) 2019Zhang Zhou Ying Xiao al.Human cleaving robust homozygotic substitutions base.Genome 20: 101Crossref (11) 2017Li Shang Highly discarded embryos.Protein 776-779Crossref (55) 2018Zeng Correction Marfan Syndrome Pathogenic FBN1 Mutation Cells Heterozygous Embryos.Mol. Ther. 26: 2631-2637Abstract (71) efficient: higher 50% cases. Indels response mechanisms deaminated base. flanking bystander effects (Kim 2017Kim Komor Levy K.T. Increasing genome-targeting scope precision Cas9-cytidine fusions.Nat. 35: 371-376Crossref (381) four 12 indels. About 60% corrected (Rees Liu, 2018Rees H.A. editing: chemistry transcriptome living cells.Nat. 19: 770-788Crossref (521) 2019, Anzalone method limitations. Prime uses nickase recruitment transcriptase just strands. attendant gRNA include copying single-stranded nick (Anzalone 2019Anzalone A.V. Randolph P.B. Davis J.R. Sousa A.A. Koblan L.W. P.J. Wilson Newby G.A. Raguram Search-and-replace DNA.Nature. 576: 149-157Crossref (969) allows wider spectrum DSB. genes responsible sickle Tay Sachs, Liu’s group similar compared CRISPR-triggered key steps performed exogenously enzymes, required seal species dependent. It important consequences type. introduced 10%–50% loci (Aida 2020Aida Wilde Hou Lu primarily induces undesired mice.bioRxiv. (2020.08.06.239723)Google 2020Liu models system.Cell Discov. 27Crossref (52) observed unintended change. there insufficient anticipate nuclear mutations, caused mitochondrial Mitochondrial disorders among inherited metabolic debilitating fatal age. Given pharmacologic agents disorders, current largely supportive. Forms ha
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ژورنال
عنوان ژورنال: Cell
سال: 2021
ISSN: ['0092-8674', '1097-4172']
DOI: https://doi.org/10.1016/j.cell.2021.02.036