1) The cloning or identification of a gene for a particular disease based on its location in the genome, determined by a collection of methods including linkage analysis, genomic (physical) mapping, and bioinformatics, when no information about the biochemical basis of the disease is known; distinguished from the more common strategy of gene cloning beginning with a known protein product, determining its amino acid sequence, and using that information to isolate the gene.

2) Positional cloning is a laboratory technique used to locate the position of a disease-associated gene along the chromosome. This approach works even when little or no information is available about the biochemical basis of the disease. Positional cloning is used in conjunction with linkage analysis. It involves the isolation of partially overlapping DNA segments that progress along the chromosome toward a candidate gene.