Which term refers to mice that have had specific genes blocked or removed?

The term that refers to mice that have had specific genes blocked or removed is "knockout mice." Knockout mice are genetically engineered to deactivate or "knock out" one or more specific genes. This process allows researchers to study the effects of the absence of these genes on the organism's development, physiology, and behavior. By observing how the knockout mice differ from normal mice, scientists can gain insights into the role of those specific genes in health and disease.

Transgenic mice, on the other hand, have had new genes introduced into their genome, which is quite different from having genes removed or knocked out. Mutant mice generally refer to any mice with naturally occurring genetic mutations, but not specifically those that have undergone targeted gene removal. Hybrid mice result from the mating of different strains of mice and are used for various genetic studies, but they do not specifically imply the removal of genes. Thus, knockout mice accurately describe the process of gene removal or blockage.