Restoration of radiation resistance in ataxia telangiectasia cells by the introduciton of normal huma chromosome 11

In order to identify the human chromosome which carries a mutated gene in cells from a patient with the hereditary disorder ataxia telangiectasia belonging to complementation group D(AT-D), we performed chromosome transfer experiments via microcell fusion. A single, pSV2neo-tagged chromosome, either 11 or 12, derived from normal human firboblasts was introduced into AT-D cells by microcell fusion, and clones which were resistent to the antibiotic G418 were isolated. All 3 hybrid clones containing an additional copy number of chromosome 11 showed a restoration of the resistance of wild-type cells to killing by X-irradiation, whereas all 3 hybrid clones containing an additional copy number of chromosome 12 remained hyper-radiosensitive, like the parental AT cells. The results indicate that a defective gene of AT-D cells is also located on chromosome 11, since a genetic linkage analysis has previously suggested that a defective gene of its complementation group a is located on this chromosome. (author). 14 refs.; 2 figs.; 1 tab