Chromosomal Assay after In-vitro Irradiation of Lymphocytes in Ataxia Telangiectasia

ABSTRACT

BACKGROUND: Hypersensitivity to both cell-killing and chromosome-damaging effects of ionizing radiation is a consistent feature of cells from individuals with ataxia-telangiectasia (AT). This radiobiological behavior of AT cells is a component of genetic instability and may contribute to cancer risk. Also, heterozygotes for AT-mutated (ATM) genes have no clinical expressions of AT, but may become cancer prone with a moderate increase in in-vitro radiosensitivity. METHODS: We performed a chromosomal analysis on lymphocytes from 3 AT patients, 5 obligate AT carriers (siblings and parents of the patients), and 5 normal controls. RESULTS: Increases in chromosomal breakages after irradiation with 1 gray/min in cells from AT patients ranged from 0.65 to 0.83 rearrangements per metaphase, while in the carriers and controls the levels of breakage were between 0 and 0.15 per metaphase cells (P<0.05). CONCLUSIONS: These results are consistent with previously reported chromosomal radiosensitivity in AT patients. However, carriers do not show moderate radiosensitivity due to various technical factors such as the dose or distance of radiation. Although this research has some limitations due to the small numbers of patients, carriers and controls, this method may be an easy and useful diagnostic tool for AT patients in Korea. (J Korean Neurol Assoc 19(5)509~513, 2001)