CRISPR: Editing Genes

The idea of correcting a genetic disorder before a child is born once seemed purely fictional. Today, advances in genetic engineering have made this possibility increasingly realistic. At the center of this scientific shift is CRISPR, a powerful gene-editing technology that has dramatically changed how researchers study and manipulate DNA.

Gene-editing tools have progressed through three major stages of development. The earliest methods relied on zinc-finger nucleases (ZFNs), followed by transcription activator-like effector nucleases (TALENs). The most recent and widely used approach is clustered regularly interspaced short palindromic repeats, known as CRISPR, together with CRISPR-associated proteins such as Cas9 [1]. Compared to earlier techniques, CRISPR is simpler to design, more efficient, and easier to adapt, which has driven its rapid adoption across biological research.

CRISPR systems operate as RNA-guided protein complexes that can recognize and cut specific DNA sequences. These systems originated as a natural immune defense in bacteria and archaea, protecting them from invading viruses and foreign genetic material. Scientists have repurposed this mechanism to precisely edit genes in living cells, making CRISPR a promising tool for treating inherited disorders caused by single-gene mutations [2].

Currently, Cas9 and Cas12a are the only CRISPR-associated enzymes routinely used for genome editing. While they share a common function, their structural and mechanistic differences allow researchers to tailor CRISPR-based tools for a wide range of applications. [3] The most commonly used enzyme, Cas9 from Streptococcus pyogenes, requires a short DNA sequence known as a protospacer-adjacent motif, or PAM, to bind its target. Its preferred PAM sequence, NGG, is found frequently across many genomes, enabling CRISPR to be applied broadly in plant research, animal studies, and biomedical science. [1]

Beyond its role in gene editing, CRISPR has become an important diagnostic platform. CRISPR-based detection systems can identify disease-associated DNA or RNA using fluorescence, colorimetric changes, or electrical signals, leading to a diverse range of diagnostic methods with high sensitivity and specificity. [4]

In cancer research, CRISPR has enabled the development of genetically defined human cancer models and has been used to detect cancer-specific genetic alterations. For example, microsatellites - short repeated DNA sequences that often change in cancer cells - can be accurately identified through CRISPR-mediated enzymatic digestion. [5]

Research efforts are now expanding CRISPR applications beyond traditional biomedical uses. Scientists are exploring the potential of CRISPR-Cas systems in bioengineering, including the development of smart materials such as hydrogels that can respond to biological signals. [3] However, controlling CRISPR activity through transcriptional regulation can be challenging, as the process involves multiple time-consuming steps, including gene expression and protein assembly, which limits its effectiveness in certain contexts. [6]

Despite its transformative potential, CRISPR technology presents notable risks. Introducing double-strand breaks in DNA can result in unintended large deletions or complex chromosomal rearrangements, sometimes triggering chromothripsis. These changes may disrupt tumor-suppressor genes or activate the p53 pathway, leading to cell death or abnormal cell selection. [5] Additionally, most FDA-authorized CRISPR-based diagnostic tests currently require centralized laboratory settings due to complex handling procedures. As protocols become simpler, CRISPR diagnostics may eventually be used in clinics and homes, potentially reshaping how diseases are detected and monitored. [7]

References

1. Li T, Yang Y, Qi H, Cui W, Zhang L, Fu X, et al. CRISPR/Cas9 therapeutics: Progress and Prospects. Signal Transduction and Targeted Therapy [Internet]. 2023 Jan 16 [cited 2026 Jan 4];8(1):1–23. Available from: https://www.nature.com/articles/s41392-023-01309-7

2. Chavez M, Chen X, Finn PB, Qi LS. Advances in CRISPR therapeutics. Nature Reviews Nephrology [Internet]. 2022 Oct 24 [cited 2026 Jan 4];19. Available from: https://www.nature.com/articles/s41581-022-00636-2

3. Paul B, Montoya G. CRISPR-Cas12a: Functional overview and applications. Biomedical Journal [Internet]. 2020 Feb 1 [cited 2026 Jan 4];43(1):8–17. Available from: http://www.sciencedirect.com/science/article/pii/S2319417019305050?via%3Dihub

4. Kim S, Ji S, Koh HR. CRISPR as a Diagnostic Tool. Biomolecules [Internet]. 2021 Aug 6 [cited 2026 Jan 4];11(8):1162. Available from: https://www.mdpi.com/2218-273X/11/8/1162

5. Katti A, Diaz BJ, Caragine CM, Sanjana NE, Dow LE. CRISPR in cancer biology and therapy. Nature Reviews Cancer [Internet]. 2022 Feb 22 [cited 2026 Jan 4];22(22). Available from: https://www.nature.com/articles/s41568-022-00441-w

6. Shivram H, Cress BF, Knott GJ, Doudna JA. Controlling and enhancing CRISPR systems. Nature Chemical Biology [Internet]. 2021 Jan 1 [cited 2026 Jan 4];17(1):10–9. Available from: https://www.nature.com/articles/s41589-020-00700-7

7. Abudayyeh OO, Gootenberg JS. CRISPR diagnostics. Science [Internet]. 2021 May 28 [cited 2026 Jan 4];372(6545):914–5. Available from: https://www.science.org/doi/full/10.1126/science.abi9335

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