Congenital strain

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Congenic strains are strains in which part of the genome of one inbred strain (strain A) is purposefully inserted into the genetic background of another inbred strain (strain B). Since even the congenic strain is inbred, i.e. homozygous throughout the entire genome, the only genetic difference between strain B and congenic strain B.A# (where # is the specific number of the chromosomeu) is precisely the so-called differential segment [ [chromosome]]u #. If strains B and B.A# differ in some phenotypic characteristic (weight, glycemia, or sensitivity to teratogen), it is possible to conclude that it is in the differential segment that gene or genes involved in the genetic determination of the measured trait. Special cases of congenic strains are consomic and conplastic.