Terminology that is currently used in the description of pseudoallelism. In the cis configuration both mutant recons are on one homolog and both wild-type recons are on the other (a 1 a 2/++). The phenotype observed is wild type. In the trans configuration each homolog has a mutant and a nonmutant recon (a 1+/+a 2), and the mutant phenotype is observed. In the case of pseudoallelic genes, the terms cis and trans configurations correspond to the coupling and repulsion terminology used to refer to nonallelic genes. See transvection effect.
Subjects: Genetics and Genomics.