trans configuration /-kənfig′yərā″shən/ [L, trans + configurare, to form from] , 1. an arrangement in which the dominant allele of one pair of genes and the recessive allele of another pair are on the same chromosome. 2. an arrangement in which at least one mutant gene and one wild-type gene of a pair of pseudoalleles are present on each chromosome of a homologous pair. Also called trans arrangement, trans position. Compare cis configuration, def. 1. 3. in chemistry, a form of geometric isomerism in which two substituent groups occur on opposite sides of a structure such as a ring or a double bond. Also called E (entgegen) configuration. Compare cis configuration, def. 3.
