Library · Biology & lab methods
What Gene Deletion Engineering got wrong, from 29 theses
Summary written by a model from the records below: The records detail engineering difficulties encountered when designing, generating, and validating gene and locus deletions across various experimental models. Many attempts suffered from synthetic lethality, unintended off-target damage, genetic redundancy, or severe loss of cellular fitness and protein stability. These records come from graduate theses, 2021 to 2026, each labeled with its degree where the repository states it, and each links to its thesis. They were extracted by language models reading the full text, so treat each as a lead to read, not a verdict.
Plus 9 problems the authors left open, listed at the end.
Failure modes, by theses reporting them
Select a mode to jump to its records.
Deletion of essential genes or combinatorial targets causes lethality and strain inviability
Targeted gene knockouts frequently fail when deleting an essential gene or unintentionally disrupting adjacent essential loci. Combining multiple deletions also regularly triggers synthetic lethality that prevents viable transformants or cell propagation.
Tried and failed
large targeted genomic deletion using dual gRNAs applied to promoter region of a target gene. Reason: deletion inadvertently removed an essential adjacent gene leading to homozygous lethality
Regulation of Active DNA Demethylation and its Role in Fertility in Arabidopsis thaliana · MIT · PhD
Tried and failed
in-frame gene deletion mutagenesis applied to bacterial target gene knockout. Reason: The target gene deletion was unsuccessful and suspected to be lethal to the organism.
Molecular mechanisms of microbial pathways for environmental contaminant remediation · Georgia Tech · PhD
Tried and failed
Complete knockout of essential ribonuclease gene applied to Bacterial host metabolic engineering. Reason: Ribonuclease E is essential for bacterial cell viability, causing lethality upon complete deletion.
Enhancing biomolecule production through microbial engineering and advanced manufacturing · UT Austin · PhD
Tried and failed
combinatorial targeted gene deletion applied to bacterial membrane protein homeostatic pathways. Reason: simultaneous loss of functional genes caused synthetic lethality, resulting in inviable transformants or suppressor mutations
THE FUNCTION OF TERC PROTEINS IN METAL HOMEOSTASIS · Cornell · PhD
Tried and failed
dual genetic deletion of cell wall synthesis machinery applied to bacterial cell envelope assembly pathways. Reason: simultaneous loss of both peptidoglycan polymerization pathways causes synthetic lethality and prevents cell growth
Genetic analysis of cell envelope assembly and polar growth in Corynebacterium glutamicum · Harvard · PhD
Tried and failed
combinatorial gene deletion with fluorescent tagging applied to cell cycle regulatory network mutants. Reason: the combined genetic perturbations resulted in synthetic lethality and non-viable strains
The coordination of cell growth and division by CDK in fission yeast · Imperial · PhD
Tried and failed
CRISPR deletion of polyadenylation site applied to leukemia cell line propagation. Reason: clones with targeted polyadenylation site deletion were non-viable or failed to propagate
The Role of Alternative Splicing and Alternative Polyadenylation in Regulating Activated T cell Biology · Penn · PhD
Unintended structural mutations and collateral disruption of adjacent loci cause genomic instability
Attempting targeted deletions often results in large rearrangements outside homology arms, loss of heterozygosity, or unintended plasmid loss. These wide deletions also impair adjacent gene expression or generate aberrant truncated transcripts.
Considered and rejected
Considered and rejected: Rejected gDNA-transformation-based gene deletion due to unintended plasmid pBS32 loss and off-target mutations, replacing it with SPP1 phage transduction.
Considered and rejected
Considered and rejected: Founder line 4044 for Fcer1g-loxP was rejected due to a large genomic deletion outside homology arms resulting in a null allele rather than a functional conditional allele.
Microglia and Myelin: Improved Tools and Molecular Interactions · MIT · PhD
Considered and rejected
Considered and rejected: CRISPR/Cas9 knockout of the IL13RA1-LOR1a terminal exon in NCI-H358 cells was rejected in favour of transient ASO/siRNA knockdown because genomic deletion simultaneously reduced canonical IL13RA1 expression.
Retrotransposable element co-option in the evolution of immune networks · Imperial · PhD
Considered and rejected
Considered and rejected: Rejected large genomic deletions for CRISPR knockout in favor of small 200-300 bp deletions to prevent inadvertently impacting adjacent Cbx gene expression.
Dissecting differences in function of Cbx paralogs during differentiation to neural progenitor cells · Harvard · PhD
Considered and rejected
Considered and rejected: Rejected CRISPR deletion strategy 2 (deleting sequence between polyA sites while preserving distal polyA site) because it generated an ectopic, truncated transcript.
Molecular and physiological roles of long 3' UTR mRNA isoforms in neurons · University of Nevada, Reno · PhD
Considered and rejected
Considered and rejected: Dual CRISPR-nuclease targeting (upstream and downstream deletion) to inactivate one TP53 allele was rejected because resulting cell lines were genetically unstable and lost the remaining allele via loss of heterozygosity (LOH).
Functional characterization of the TP53 mutome using CRISPR/Cas9 saturating mutagenesis Functional characterization of the TP53 mutome using CRISPR/Cas9 saturating mutagenesis · University of Marburg · PhD
Engineered deletions impair cellular fitness and fail to match baseline strain performance
Knocking out regulatory or metabolic genes frequently leads to pleiotropic defects, severe viability loss, and chlorosis. In production assays, deletion strains are often outcompeted by unengineered baselines and fail to deliver synergistic metabolic improvements.
Tried and failed
glycogen biosynthesis gene knockout applied to cyanobacteria metabolic engineering. Outcome: unstable. Reason: deletion caused severe viability loss, chlorosis, and loss of natural transformability
Synthetic microbial communities and multiplexed metabolic tuning by CRISPRai for enhanced bioproduction · Imperial · PhD
Tried and failed
target gene deletion for byproduct reduction applied to engineered microbial sucrose secretion. Outcome: worse than baseline. Reason: deletion did not increase target metabolite secretion over the high-producing baseline strain
Synthetic microbial communities and multiplexed metabolic tuning by CRISPRai for enhanced bioproduction · Imperial · PhD
Lost to a baseline
Control strain eBA26 (without chromosomal deletions) displayed higher glucose consumption rate, total β-alanine titer, and biomass formation than engineered deletion strains in minimal medium
Enhancing biomolecule production through microbial engineering and advanced manufacturing · UT Austin · PhD
Lost to a baseline
pgm2 deletion and aim10/gal10 binary knockouts outcompeted in competitive serial growth on galactose compared to baseline fitness benchmarks, showing moderate knockdown was superior.
Microdroplet assay development for metabolic engineering and synthetic biology applications · UT Austin · PhD
Considered and rejected
Considered and rejected: Rejected deleting the zur regulator to deregulate [S,S]-EDDS biosynthesis because zur deletion caused undesirable pleiotropic side effects and reduced physical fitness
Investigation on the synthesis of the aminopolycarboxylate metallophores EDHA and [S,S]-EDDS in actinomycetes · Tübingen · PhD
Tried and failed
combinatorial stacking of beneficial single-gene knockouts applied to recombinant protein production in yeast. Outcome: worse than baseline. Reason: multiple deletions showed no synergistic productivity improvement and often impaired cellular production capacity
Low editing efficiency and delivery artifacts impede the recovery of full genomic deletions
Multiplex and dual-guide CRISPR approaches often show poor cutting rates and fail to produce full gene deletions. Investigators frequently abandon double-strand break deletion strategies due to low editing frequencies, PCR size biases, and screening artifacts.
Tried and failed
dual sgRNA CRISPR-Cas9 targeted gene knockout applied to targeted genomic deletion screening. Outcome: no signal. Reason: specific sgRNA combination failed to generate targeted genomic deletion or cleavage products
Identifying mechanisms of resistance to CDK4/6 inhibitors in breast cancer · Imperial · PhD
Tried and failed
CRISPR-Cas9 locus deletion applied to cancer cell microRNA clusters. Outcome: no signal. Reason: poor cutting efficiency detected in mismatch cleavage assays
Targeting oncogenic microRNAs in malignant germ cell tumours. · Cambridge · PhD
Considered and rejected
Considered and rejected: CRISPR-Cas9 whole-gene deletions of yolk protein genes were discontinued after failing to recover whole gene deletions despite recovering small indels.
DYNAMICS REGULATING A TRADE-OFF BETWEEN EGG PRODUCTION AND BACTERIAL IMMUNE DEFENSE IN DROSOPHILA MELANOGASTER · Cornell · PhD
Considered and rejected
Considered and rejected: Switched from Cas9 double-strand break deletion to CRISPRi interference because low editing frequency and sorting artifacts prevented bulk proteomic profiling.
Life without Replication in Bacillus subtilis · Leibniz Universität Hannover · PhD
Considered and rejected
Considered and rejected: Rejected CRISPR-Cas9 dense tiling mutagenesis for future single-enhancer dissection in favor of landing pad-based editing due to contiguous deletion limitations and PCR size biases.
CRISPR Screening Uncovers Long-Range Enhancers in Pancreatic Differentiation and Links a Diabetes Risk Variant · Cornell · PhD
Genetic redundancy and compensatory suppressor mutations mask expected deletion phenotypes
Single gene deletions often fail to eliminate target pathways because redundant defense mechanisms or enzymes maintain the wild-type function. In other contexts, rapid emergence of compensatory suppressor mutations or trans-complementation during co-infection masks the mutant defect.
Tried and failed
single-gene knockouts to recapitulate suppressor phenotype applied to starvation lethality rescue in metabolic mutants. Outcome: no signal. Reason: individual deletions failed to reproduce the phenotypic suppression observed in isolated suppressor strains
Investigating starvation survival in Saccharomyces cerevisiae · Cornell · PhD
Considered and rejected
Considered and rejected: Single deletion of pglE was rejected for mutasynthesis host construction because it failed to completely abolish phenylglycine production.
Generation of novel pristinamycin I derivatives by mutasynthesis · Tübingen · PhD
Tried and failed
single-gene knockout of redundant defense systems applied to bacterial host susceptibility to phage. Reason: Multiple redundant defense elements compensate for individual knockouts, requiring simultaneous multiplex deletion to restore susceptibility.
Tried and failed
Targeted gene deletion in competitive infection assays applied to Assessing bacterial virulence factors in vivo. Outcome: no signal. Reason: Trans-complementation by the wild-type strain masked the mutant fitness defect during co-infection
The Two-Component System PhoRP-Dependent Proinflammatory Response from Infection with Mycobacterium abscessus in Cystic Fibrosis. · Harvard · Master's
Peptide truncations and domain deletions disrupt protein folding and expression
Shortening protein coding sequences by deleting terminal peptides or functional domains causes severe loss of dimer stability and protein aggregation. Such structural truncations regularly render expressed proteins completely insoluble or eliminate baseline reporter expression.
Considered and rejected
Considered and rejected: Abandoned shortened C-terminal deletion constructs (Trt1short) due to severe loss of dimer stability and aggregation.
Structural determination of Entamoeba Histolytica TGT and its binding to tRNAASP · Leibniz Universität Hannover · PhD
Tried and failed
truncation of terminal peptide region applied to recombinant viral protein expression. Outcome: unstable. Reason: deletion of the peptide rendered the expressed protein insoluble
THE MASTER MANIPULATOR; CRYSTAL CLEAR PERSPECTIVES ON VIRAL INFECTIVITY · Cornell · PhD
Considered and rejected
Considered and rejected: Rejected using truncated deletion mutants (e.g. CBU1314ΔNLSs or CTD deletions) due to severe loss of baseline Renilla reporter expression or complete lack of effector protein expression.
Evasion Of Innate Immunity By The Pathogen Coxiella Burnetii · Penn · PhD
Left open by the authors
Problems the authors named and did not get to.
Left open
Implement CRISPRi or targeted gene deletions in E. coli starter cultures to genetically tune toxic and beneficial metabolite pools. Blocker: Requires a wet lab and physical genetic engineering/metabolic profiling equipment
Interfacing systems and synthetic biology for advancements in bacterial biosensor engineering · Georgia Tech · PhD
Left open
Conduct systematic deletion mutagenesis studies in LacI/GalR family members like the ribose repressor based on identified indel discoveries. Blocker: Requires a wet-lab molecular biology environment to engineer mutant strains and measure repression phenotypes.
Exploring Allosteric Communication in the Lactose Repressor · Georgia Tech · PhD
Left open
Construct and experimentally characterize the yabP deletion mutant in E. coli to validate thermotolerance predictions. Blocker: Requires wet-lab genetic engineering and growth assays.
Microbial engineering, characterization, and applications through novel data processing and synthetic biology systems · Iowa State · PhD
Left open
Refine the sugar-phosphate toxicity biocontainment kill switch in vivo by testing alternative gene deletions, mouse diets, and LF82-specific phage cocktails. Blocker: Requires a wet lab, bacterial strains, animal facility (mice), and phage engineering capabilities
Investigating the role of genetic variation in the emergence of new phenotypes in an Escherichia coli pathobiont · Iowa State · PhD
Left open
Generate a clean deletion of prophage Φ12 in S. aureus HG003 and test its intramacrophage survival phenotype. Blocker: Requires a molecular microbiology wet lab, bacterial genetic engineering, and macrophage infection assays.
Uncovering Genes Involved in Staphylococcus aureus Survival and Persistence in Macrophages · Harvard · PhD
Left open
Perform targeted deletion of AC, PDE, or cAMP-CRP binding sites on flhDC to test their roles in swarm development. Blocker: Requires a molecular biology wet lab and genetic engineering of Proteus mirabilis strains
Proteus mirabilis adapts to environmental change through regulation of its developmental cycle · Harvard · PhD
Left open
Screen novel transcription factor gene deletion strains using promoter-reporter assays to map indirect regulation pathways in E. coli. Blocker: Requires wet-lab molecular cloning, bacterial strain engineering, and experimental kinetic assays.
Confirming sRNA Transcriptional Regulators in E. coli · UT Austin
Left open
Perform CRISPR-Cas9 systematic deletion of MSY-specific insertions in lncRNA LOC143420689 to functionally validate candidate QTNs and genes. Blocker: Requires a wet lab, live cichlid fish specimens, and CRISPR-Cas9 gene editing apparatus.
Structural Variation in Adaptive Radiation: Determining the Potential Role of Large Genomic Inversions in Lake Malawi Cichlids · Georgia Tech · PhD
Left open
Test subdeletions of the 5'Δ0.8 region (ROS1Δ4, ROS1Δ5, ROS1Δ2, ROS1Δ3) in Arabidopsis thaliana to isolate causal silencing sequences. Blocker: Requires wet lab facilities, plant transformation, and genetic crossing in Arabidopsis thaliana
Regulation of Active DNA Demethylation and its Role in Fertility in Arabidopsis thaliana · MIT · PhD
Who has worked on this
Authors of the public theses cited on this page, most-cited first.
- Lucie Studená · Imperial · PhD · 2022
Synthetic microbial communities and multiplexed metabolic tuning by CRISPRai for enhanced bioproduction - Deborah Allison Pohlmann · MIT · PhD · 2022
Regulation of Active DNA Demethylation and its Role in Fertility in Arabidopsis thaliana - Nikesh Manish Kumar · Georgia Tech · PhD · 2026
Structural Variation in Adaptive Radiation: Determining the Potential Role of Large Genomic Inversions in Lake Malawi Cichlids - Hayley Ford · MIT · PhD · 2026
Genetic Modifications and Other Tools for the Enhancement and Optimization of Recombinant Protein Manufacturing in Komagataella phaffii - Kim Walbrunn · Leibniz Universität Hannover · PhD · 2026
Structural determination of Entamoeba Histolytica TGT and its binding to tRNAASP - Billy Whyte · Imperial · PhD · 2025
The coordination of cell growth and division by CDK in fission yeast - Jenny Kim · Harvard · PhD · 2025
Uncovering Genes Involved in Staphylococcus aureus Survival and Persistence in Macrophages - Tobias William Plowman · Imperial · PhD · 2025
Retrotransposable element co-option in the evolution of immune networks - Zachary Dean Herde · Georgia Tech · PhD · 2025
Exploring Allosteric Communication in the Lactose Repressor - Kristin Velten · University of Marburg · PhD · 2025
Characterization of the DUF4004 protein YhbD of Bacillus subtilis: A connection to bactofilins and vancomycin-mediated switch of YhbD between membrane localization and DNA binding Charakterisierung de - Oliver Hennrich · Tübingen · PhD · 2025
Generation of novel pristinamycin I derivatives by mutasynthesis - Sarah DeWolf · Iowa State · PhD · 2025
Investigating the role of genetic variation in the emergence of new phenotypes in an Escherichia coli pathobiont
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