Quantitative Extra Long PCR to Detect DNA Lesions in Patients Exposed to Low Doses of Diagnostic Radiation

Document Type: Research Articles

Authors

1 Department of Pathology, Dr. Ram Manohar Lohia Institute of Medical Sciences, Lucknow, India.

2 Department of Pathology, King George’s Medical University, Lucknow, India.

3 Radiation Oncology, Dr. Ram Manohar Lohia Institute of Medical Sciences, Lucknow, India.

4 Radiodiagnosis, Dr. Ram Manohar Lohia Institute of Medical Sciences, Lucknow, India.

Abstract

Background: Radiation causes oxidative lesions and strand breaks in DNA of exposed cells. Extended length
PCR is a reliable method for assessing DNA damage. Longer DNA strands with DNA damage are difficult to amplify
compared to smaller DNA strands by PCR. The present study was aimed to evaluate DNA damage caused by ionising
radiation exposure in therapeutic and diagnostic medicine. Materials and Methods: The study group comprised 50
cases with low dose single exposure (LDS), low dose multiple exposure (LDM) and low dose angiography (LDA)
which were compared with 25 high dose controls (HDC) and 25 controls with no exposure (NEC). Blood samples were
collected within 1 hour of radiation exposure. DNA was isolated using a kit based protocol, 50 ng aliquots of DNA
were used to amplify a long 13kbp DNA fragment of the β-actin gene by conventional PCR and band intensity was
then quantified. Relative amplification was calculated and damage was expressed in terms of lesions per kilobase (kbp)
by assuming a Poisson distribution. Result: Relative amplification was found to be 1.0, 0.87, 0.86, 0.72 and 0.69 with
NEC, LDS, LDM, LDA and HDC groups, respectively. Cases undergoing angiography as well as high dose controls
had high values, compared to NEC. The lesions/kbp calculated for LDS was 0.13, for LDM 0.15, for LDA 0.32 and
for HDC 0.37 suggesting a linear increase in quantity with increasing radiation dose. Conclusion: DNA damage, even
at low doses of radiation can be assessed by quantitative extra long PCR.

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