Stable-isotope-dilution tandem mass spectrometry is the most advanced technique used for quantitative determination of a wide spectrum of endogenously generated DNA nucleobase modifications. It is regarded as a gold standard for such analyses. Here, we consider the requirements for reliable identification and quantification of DNA adducts/modifications, whether endogenously derived or not, and discuss how their quantification can provide information on the mechanism of action and the biological relevance of individual nucleobase modifications. A clinical application of such measurements will only be possible after a full validation of the assay and once we have gained a better understanding of the exact role that these DNA modifications play in disease pathogenesis. Once these prerequisites are satisfied, DNA modification measurements may be helpful as clinical parameters for treatment monitoring, for risk group identification and for the development of prevention strategies.
Keywords: 5-carboxycytosine; 5-formylcytosine; 5-hydroxymethylcytosine; 5-hydroxymethyluracil; 5-methylcytosine; 8-oxo-7,8-dihydroguanine; DNA base modifications; Isotope dilution; Tandem mass spectrometry; Uracil; Urinary excretion.