In human genetics, a strategy for identifying the gene responsible for a disease by mapping the mutant gene to a specific chromosomal region and then looking for an appropriate candidate among the genes already localized in that region. Individuals suffering from the disease are then tested for mutations in the candidate gene. For example, a gene encoding a fibroblast growth factor receptor (FGFR3) protein was discovered during a chromosome walk (q.v.) toward the Huntington disease gene. Next, the gene for achondroplasia (q.v.) was mapped to the same chromosomal region. Finally, the FGFR 3 genes of dwarfs were found to contain missense mutations, proving that mutations of the FGFR 3 gene were responsible for the retarded growth characterizing the disease.
Subjects: Genetics and Genomics.