A technique used by researchers to zero in on the gene(s) responsible for a given trait or disease. A genetic map of the organism’s genome is used to make an educated guess as to the precise location of the gene of interest (e.g., near marker or , etc.). Then those guessed genes are cloned, inserted into living organisms or cells, and tested to see if the guessed gene causes expression of the protein of interest (e.g., a protein that causes the disease that the researcher is attempting to cure).