isogenic

Isogenic describes organisms or cells that are genetically identical or nearly identical, typically derived from a common ancestor or a common genetic background. The term is used across biology to indicate a uniform genetic baseline that can be compared when studying the effect of a specific gene, mutation, or treatment.

In practice, isogenic materials are created to minimize background genetic variation. In cell biology, isogenic cell lines are produced by starting with a parental line and engineering a defined genetic change, then isolating clones that share the same background except for the targeted modification. This allows researchers to attribute observed differences to the modification rather than to other genetic differences. In microbiology and cancer research, isogenic strains or lines are used to compare the impact of a gene alteration or drug treatment within a consistent genomic context.

In plant and animal genetics, the concept appears as near-isogenic lines (NILs) or isogenic lines achieved through repeated backcrossing or cloning, so that all genetic material except a specific region or locus is held constant. NILs are especially valuable for dissecting the role of a single genomic interval on a trait.

Limitations include the difficulty of achieving perfect isogeneity. Over generations, spontaneous mutations, genetic drift, and epigenetic differences can introduce variation. Additionally, extranuclear genomes (such as mitochondrial DNA) and environmental factors can influence phenotype despite nuclear identity.

Etymology: isogenic derives from Greek isos, meaning equal, and genos, origin. See also NILs, cloning, and targeted genetic modification.