Gene Mapping by Fluorescence In Situ Hybridization

Gene mapping by fluorescence in situ hybridization (FISH) is the localization of a unique DNA sequence (probe) to a specific position (chromosomal band) within the genome (target). The DNA probe localization on the target is visualized using a fluorescent reporter molecule directly or indirectly bound to the probe. Although gene mapping by FISH usually refers to the localization of a gene or DNA sequence to a specific metaphase chromosome band, it can also include the relative position of genes along a chromatin or DNA fiber, or the identification of specific genomic BAC/PAC clones present in an array. FISH combines the specificity of recombinant DNA technology with basic cytogenetic techniques for target DNA preparation. Valuable information regarding the biological and/or clinical significance of a gene can be obtained by identifying its subchromosomal location in both normal and disease conditions. Mapping a gene to certain critical chromosomal regions that may be deleted, amplified, or involved in translocation breakpoints can provide important information about the role of that gene in disease processes and may have significant clinical applications. Important information regarding gene function can also be obtained from mapping genes from individual tissues or disease states, identifying transgene insertion sites, studying interspecies synteny, and determining the order of and distance between two or more genes within a chromosome band. Keywords: BAC; Chromosomal Bands; Chromatin Fibers; Released Chromatin Fibers; Released DNA Fiber; FISH; Interphase Nuclei; Metaphase Chromosome; PAC; YAC