horizontal gene transfer

noun

Medical Definition of horizontal gene transfer

: the transmission of genetic material between genomes and often between genomes of different species This acquisition of foreign genes is generally referred to as horizontal gene transfer (as opposed to vertical inheritance, in which an organism receives DNA from an ancestor).— James O. McInerney and Davide Pisani, Science, 30 Nov. 2007 Much of the genetic machinery needed to facilitate host specificity and virulence is acquired through horizontal gene transfer. Mobile genetic elements, such as transposons, plasmids, or bacteriophages, obtained from strains already adapted to specific hosts, often provide the genes necessary for selective virulence.— Franklin D. Lowy, The New England Journal of Medicine, 26 May 2011