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Hypersensitivity to ionizing radiation in cultured cells from Down syndrome patients
Abstract:
Down syndrome is caused by trisomy of chromosome 21 and is comprised of a constellation of abnormalities including neuropathological features that closely resemble those characterizing the neurodegeneration of Alzheimer disease. Because cultured cell lines from patients with Alzheimer disease and other neurodegenerations have a hypersensitivity to the lethal effects of DNA-damaging agents, we studied the response of Down syndrome lymphoblastoid lines to the lethal effects of ionizing and ultraviolet radiation. Lines from the four Down syndrome patients were more sensitive to X-rays than lines from 28 normal donors (P = 10(-4)), while survival of the Down syndrome lines after ultraviolet irradiation was not significantly different from normal. This hypersensitivity to X-rays, which may reflect defective repair of X-ray-induced DNA damage, represents the first abnormality common to cultured cells from both Down syndrome and Alzheimer disease patients.
Insights
Down syndrome cells show increased sensitivity to X-ray radiation, suggesting a potential DNA repair defect. This finding links Down syndrome to Alzheimer disease neuropathology at a cellular level.
Area of Science:
- Genetics
- Neuroscience
- Cell Biology
Background:
- Down syndrome (trisomy 21) shares neuropathological features with Alzheimer disease.
- Cell lines from neurodegenerative diseases exhibit hypersensitivity to DNA-damaging agents.
Purpose of the Study:
- To investigate the DNA damage response in Down syndrome cells.
- To compare the sensitivity of Down syndrome cells to ionizing and ultraviolet radiation with normal cells.
Main Methods:
- Cultured lymphoblastoid cell lines from Down syndrome patients and normal donors were exposed to X-rays and ultraviolet radiation.
- Cell survival rates were measured after irradiation.
Main Results:
- Down syndrome cell lines demonstrated significantly higher sensitivity to X-rays compared to normal cell lines (P = 10(-4)).
- No significant difference in survival was observed between Down syndrome and normal cell lines after ultraviolet irradiation.
Conclusions:
- Down syndrome cells exhibit hypersensitivity to ionizing radiation, potentially indicating defective DNA repair mechanisms.
- This hypersensitivity to X-rays is the first common abnormality identified in cultured cells from both Down syndrome and Alzheimer disease patients.