Positional cloning is a process in which a gene is identified by its position on a chromosome. It is also referred to as map-based cloning, chromosome walking, or positional gene cloning. Map-based cloning involves creating a genetic map of the chromosome region containing the gene of interest. Chromosome walking involves using overlapping DNA fragments to progress along the chromosome until the gene is identified. Positional gene cloning involves screening a library of cloned DNA fragments for the gene of interest. These synonym terms are all used interchangeably to describe the process of identifying genes based on their physical location on the chromosome, and they provide researchers with tools to identify genetic defects and better understand the mechanisms of various diseases.