Animals which have been bred to be genetically identical except for a single gene locus. This is achieved by superimposing the locus of interest on the genetic background of another by first crossing two inbred lines followed by extensive (about 20 generations) backcrossing hybrids to one parental line (the background strain) while selecting for the alleles of the locus of interest of the other. The result is an inbred strain uniquely identified by a difference at a single locus.

Organisms that differ in genotype at a single locus.

Strains that are identical except for a small region of the chromosome.

variant strain of mice that is formed by backcrossing to an inbred parental strain for ten or more generations while maintaining heterozygosity at a selected locus (see Chapter 3). See Congenic in the MGI Glossary.

a strain of animals that is formed by backcrossing to an inbred parental strain for ten or more generations while maintaining heterozygosity at a selected locus. Resulting strains are assumed to differ only at this small heterozygous chromosomal region. [Source: Source: NHBLI/NCBI Glossary

Nearly identical strains of an organism; they vary at only a single locus.

Animals which are genetically constructed to differ at one particular locus.

In genetics, two organisms that differ in one locus are defined as congenic.