Double heterozygote: An individual who is heterozygous at two loci under investigation.
This differs from , which refers to an individual who is heterozygous for mutations at two separate genetic loci, which together manifest disease.
The term proposed by Haldane (1941), by analogy with chemical isomerism, to describe a double heterozygote in coupling phase, that is, with the two dominant factors derived from one parent and the two recessives from the other.
When gametes form in s (for example, a green/yellow–round/wrinkled plant), these genes assort independently, because the two chromosomes that bear them assort independently.
examples of individuals possessing the following genotypes: AaBb, Aabb, aaBb, and aabb. Assuming linkage between the loci, if both AaBb and aabb progeny are rare, then what alleles were located on the same chromosomes of the double heterozygote?
See also: Heterozygote, Sequence, Chromosome, Trans, DNA