genetic modification gene trap GT A genetic modification induced by insertion of a nucleic acid construct containing a reporter gene sequence downstream of a splice acceptor site that is capable of integrating into random chromosomal locations Integration of the gene trap into an intron allows the expression of a new mRNA containing one or more upstream exons followed by the reporter gene. The reporter gene is therefore expressed in the same cells and developmental stages as the gene into which the gene trap has inserted. Helen Parkinson Ballard JW. Comparative genomics of mitochondrial DNA in Drosophila simulans. J Mol Evol. 2000 Jul;51(1):64-75. PubMed PMID: 10903373 doi:10.1007/s002390010067