Conditional vs Conventional Knockout

Choose Conditional If:

• Conventional knockout is embryonic lethal
• You need tissue-specific deletion
• You want temporal control over deletion
• Gene has pleiotropic effects
• You need to study adult-onset phenotypes

Choose Conventional If:

• You want global, constitutive knockout
• Faster timeline is critical (9-12 vs 12-15 months)
• Lower cost is priority
• Developmental effects are part of research question
• Gene knockout is viable and fertile

Scenario 1: Essential Developmental Gene

Research Question: What is the role of Gene X in adult heart function?

Problem: Conventional knockout of Gene X causes embryonic lethality at E10.5 due to heart development defects.

Solution: Conditional knockout with cardiac-specific Cre (αMHC-Cre) allows bypass of embryonic lethality, deletion occurs only in adult cardiomyocytes, enabling study of Gene X in mature heart function.

Scenario 2: Tumor Suppressor Gene

Research Question: How does loss of tumor suppressor Gene Y promote cancer development?

Approach: Conventional knockout is viable but mice develop tumors in multiple organs starting at 3 months, complicating analysis.

Better Solution: Conventional knockout if studying systemic tumor suppressor loss, OR conditional knockout with tissue-specific Cre if investigating organ-specific tumor suppressor function.

Scenario 3: Neuronal Signaling Gene

Research Question: Does Gene Z in hippocampal neurons regulate memory formation?

Complication: Gene Z is also expressed in cerebellum affecting motor coordination. Conventional knockout shows both memory and motor deficits.

Solution: Conditional knockout with CaMKII-Cre (hippocampus-specific) isolates memory phenotype from motor confounds, definitively answering whether hippocampal Gene Z is required for memory.