Argentina has produced the world’s first CRISPR-edited horses, sparking a global debate over genetic engineering in elite sports like polo.
- Kheiron Biotech, an Argentine biotech firm, created five cloned foals with a targeted gene edit using CRISPR-Cas9 technology.
- These foals are clones of a prize-winning horse (Polo Pureza) with suppressed expression of the myostatin (MSTN) gene to enhance muscle mass and sprinting ability.
Gene-Edited Horses
- About: Created using CRISPR-Cas9 technology to precisely edit the genome. It enhances speed, stamina, muscle growth, and recovery capacity. Unlike cloning, gene editing alters specific DNA sequences without creating an exact genetic copy.
- Beyond cloning: Earlier cloned polo ponies were produced in the 2010s; now the shift is towards direct genomic intervention.
- First approval: These horses are now entering competitive polo circuits, sparking debates worldwide.
Gene Editing
- About: Gene editing is a technology that can change DNA sequences at one or more points in the strand. It also involves removing or changing a single base or inserting a new gene altogether.
- Process: The process involves three major steps that include insertion, deletion, and modification of the gene of interest.
CRISPR Technology (Clustered Regularly Interspaced Short Palindromic Repeats)
CRISPR is a powerful gene-editing tool that allows scientists to add, remove, or alter genetic material at specific locations in the DNA sequence.
Components
- Cas9 enzyme: A molecular “scissor” that cuts DNA.
- Guide RNA (gRNA): Directs Cas9 to the exact spot in the genome to make the cut.
How it works
- The gRNA binds to the target DNA.
- Cas9 cuts the DNA at the specified location.
- Cells repair the cut either by:
- Non-homologous end joining (can disable a gene).
- Homology-directed repair (can insert new genes).
Applications
- Medicine: Gene therapy, cancer research, hereditary disease treatment.
- Agriculture: Creating pest-resistant or climate-resilient crops.
- Animals: Enhancing desired traits (e.g., muscle growth in livestock or racehorses).
Advantages
- High precision
- Cost-effective
- Faster than older gene-editing methods
Other Gene Editing Technology
- TALENs (Transcription Activator-Like Effector Nucleases): It is based on proteins from Xanthomonas bacteria that bind specific DNA sequences.
- Mechanism: DNA-binding proteins (TALEs) fused with a FokI nuclease enzyme. Recognizes and cleaves target DNA precisely.
- Applications:
- Correcting genetic diseases.
- Creating disease-resistant plants.
- Advantages: Higher precision than ZFNs.
- Limitations: Complex, labor-intensive, and more expensive than CRISPR.
- ZFNs (Zinc Finger Nucleases): It is one of the earliest gene editing tools (1990s).
- Mechanism: Artificial zinc finger proteins recognize specific DNA triplets.
- Fused with a nuclease enzyme to cut DNA.
- Applications: Used in early trials for HIV resistance.
- Advantages: Pioneered programmable gene editing.
- Limitations:
- Designing ZFNs is difficult.
- Less flexible, less efficient, risk of off-target cuts.
- Base Editing: Introduced in 2016 as a refinement of CRISPR.
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- Mechanism: Does not cut both DNA strands. Instead, uses enzymes to directly convert one DNA base to another (e.g., C→T, A→G).
- Applications: Correcting single-point mutations (cause of ~60% of genetic diseases).
- Advantages: More precise, reduces risk of double-strand breaks.
- Limitations: Works only for single-base changes, not large edits.
- Prime Editing: Introduced in 2019 as an advanced CRISPR version.
- Mechanism: Combines Cas9 nickase (modified enzyme) + reverse transcriptase enzyme. Works like a “genetic word processor” → can search, replace, insert, or delete DNA sequences.
- Applications:
- Treating complex genetic disorders (e.g., Tay-Sachs, sickle cell).
- Advantages: Extremely versatile and safer than standard CRISPR.
- Limitations: Still in the experimental stage, delivery challenges.
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Challenges of Gene Editing in Horses
- Ethical Concerns: Raises questions on animal welfare, suffering during experimentation, and long-term health effects. Philosophical debates around “naturalness” and the notion of “playing God”.
- Fairness in Sports: Gene-edited animals may lead to unfair advantages in performance-driven sports like polo, racing, etc.
- Threatens the level playing field and spirit of competition.
- Regulatory and Legal Gaps: Most sports bodies lack frameworks to deal with gene-edited animals.
- No uniform international guidelines, making enforcement difficult.
- Biodiversity and Genetic Risks: Over-reliance on engineered lineages could reduce genetic diversity. May increase vulnerability to diseases, climate stress, or mutations.
Additional Reading: About Gene Editing
1 Sep 2025
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