Once scientists pinpoint a new gene, they can map it. Distances are measured either in centimorgans or map units or physically in base pairs.
Scientists usually measure the distance from one gene to the next in both directions.
This is exactly how a new gene is mapped. Once a gene is mapped, other researchers can take a cytogenetic map and a linkage map and compare them. If they map the same gene on both types of maps, they can connect the two maps. This in turn, gives the visual picture of where a gene is found on the physical map and its genetic distance on the linkage map.