Which species are particularly used to create genetic alteration models?

• A. Mice and rats
• B. Dogs and cats
• C. Birds
• D. Reptiles

Answer: (A)

Genetic alteration models rely on species that are highly amenable to precise genome editing and can be bred quickly and cost-effectively. Mice and rats fit these needs exceptionally well.

For mice, the ability to culture embryonic stem cells historically made targeted gene modification feasible, enabling the creation of knockout and knockin lines and allowing researchers to control when and where a gene is altered using systems like Cre-LoxP. Today, advanced genome editing tools such as CRISPR/Cas9 can introduce mutations directly in embryos, speeding up the generation of diverse genetic models. The small size, rapid reproduction, and extensive collection of well-characterized strains and genetic tools create a powerful, interoperable framework for many studies, from basic gene function to disease modeling.

Rats offer similar advantages with the added benefit of a larger body and organ size, which can simplify certain physiological and toxicology experiments and make some procedures easier to perform. Like mice, modern genome editing techniques now enable efficient creation of targeted mutations in rats, expanding their usefulness for models of human biology and disease.

Other species tend to be less practical for broad genetic modification work due to longer generation times, higher maintenance costs, and fewer established genetic tools and resources, though they may be used in specific contexts.