Regional assignment of a human DNA repair gene (XRCC5) to 2q35 by X-ray hybrid mapping.

A number of human genes involved in the repair of radiation-induced DNA double-strand breaks have been identified based on the analysis of radiation-sensitive rodent mutants. Recently, one of the DSB repair genes, XRCC5, has been mapped on human chromosome 2 by concordance analysis of somatic cell hybrids and by the microcell-mediated chromosome transfer approach. For the regional mapping of the human XRCC5 gene, we have constructed a panel of X-ray hybrids and a panel of microcell-mediated chromosome 2 hybrids in the mutant background that contain only fragments of human chromosome 2. By using fluorescence in situ hybridization, chromosome banding, and physical mapping of these X-ray hybrids, we have localized the human XRCC5 locus to 2q35. This result is further confirmed by a segregation analysis indicating that the radiation resistant phenotype of a repair-proficient hybrid cosegregates with the human 2q35 chromosome fragment.