Related Experiment Video
Updated: Aug 6, 2026
17:14
Chromosome Replicating Timing Combined with Fluorescent In situ Hybridization
Published on: December 10, 2012
Radioresistant DNA synthesis and human genetic diseases
1Laboratory of Radiobiology and Environmental Health, University of California, San Francisco 94143.
Human Genetics
|May 1, 1989
Summary
Radioresistant DNA synthesis (RDS) was studied in human cells. While most ataxia-telangiectasia (AT) cells showed RDS, it was not a universal trait in AT or other genetic disorders involving radiosensitivity.
Area of Science:
- Genetics
- Cell Biology
- Radiation Biology
Background:
- Radioresistant DNA synthesis (RDS) is a characteristic observed in some human genetic disorders.
- Ataxia-telangiectasia (AT) is a primary example of a disease often associated with radiosensitivity.
- Understanding RDS is crucial for characterizing DNA repair mechanisms and genetic disease phenotypes.
Purpose of the Study:
- To investigate the presence and variability of radioresistant DNA synthesis (RDS) across diverse human fibroblast cell strains.
- To determine if RDS is a consistent marker for ataxia-telangiectasia (AT) and related genetic disorders.
- To explore the relationship between RDS and radiosensitivity in various human genetic conditions.
Main Methods:
- Assayed 68 human fibroblast cell strains for radioresistant DNA synthesis (RDS).
- Defined RDS as the absence of steep inhibition of DNA synthesis post-irradiation (0-20 Gy).
- Compared RDS presence in cell strains from patients with ataxia-telangiectasia (AT), AT heterozygotes, and other genetic disorders.
Main Results:
- Twenty-seven of 27 ataxia-telangiectasia (AT) cell strains tested exhibited radioresistant DNA synthesis (RDS).
- RDS was absent in cell strains from AT obligate heterozygotes, Alzheimer disease, Friedreich ataxia, Bloom syndrome, Down syndrome, and immunodeficiencies.
- Four cell strains showed less pronounced RDS, including one from Nijmegen breakage syndrome and two from AT patients.
Conclusions:
- Radioreistant DNA synthesis (RDS) is not a necessary trait for all human genetic diseases involving radiosensitivity or immunodeficiency.
- While RDS was consistently found in tested AT cell strains, its absence in other disorders highlights genetic heterogeneity.
- The study confirms RDS in all tested AT cells, contrasting with some recent reports, and emphasizes RDS's complex role in genetic radiosensitivity syndromes.
Related Concept Videos
01:08Nucleotide Excision Repair
Overview
01:39Mutations
Overview
02:46Genome Copying Errors
DNA replication is a well-evolved process that copies millions of base pairs with high fidelity during each cell division. Occasionally a wrong base or a long stretch of wrong bases may get added to the daughter strands. If the errors are left unchecked, cells might accumulate several mutations that might endanger their survival. Therefore, the copying errors are checked and repaired at three levels.
01:35Mutations
Mutations are changes in the sequence of DNA. These changes can occur spontaneously or they can be induced by exposure to environmental factors. Mutations can be characterized in a number of different ways: whether and how they alter the amino acid sequence of the protein, whether they occur over a small or large area of DNA, and whether they occur in somatic cells or germline cells.
Chromosomal Alterations Are Large-Scale Mutations
While point mutations are changes in a single nucleotide in...
Chromosomal Alterations Are Large-Scale Mutations
While point mutations are changes in a single nucleotide in...
01:38Nucleotide Excision Repair
DNA Distortion and Damage
Cells are regularly exposed to mutagens—factors in the environment that can damage DNA and generate mutations. UV radiation is one of the most common mutagens and is estimated to introduce a significant number of changes in DNA. These include bends or kinks in the structure, which can block DNA replication or transcription. If these errors are not fixed, the damage can cause mutations, which in turn can result in cancer or disease depending on which sequences are...
Cells are regularly exposed to mutagens—factors in the environment that can damage DNA and generate mutations. UV radiation is one of the most common mutagens and is estimated to introduce a significant number of changes in DNA. These include bends or kinks in the structure, which can block DNA replication or transcription. If these errors are not fixed, the damage can cause mutations, which in turn can result in cancer or disease depending on which sequences are...
01:18Other Unique Bacteria
Magnetic bacteria exhibit a directed movement called magnetotaxis, driven by structures called magnetosomes. These magnetosomes consist of chains of magnetic particles made of either magnetite (Fe₃O₄) or greigite (Fe₃S₄) and are organized in a linear conformation by a protein scaffold within invaginations of the cell membrane. The bacteria align along the north–south magnetic field lines, much like a compass needle. They are typically microaerophilic or anaerobic and are commonly found near the...