Detecting DNA methylation, a process used by cells to fix genes in the ‘off’ position, through a repeated enzyme reaction could help in the diagnosis of cancer.

DNA methylation can silence tumour suppressing genes and clear a path for tumour growth. It is used as a biomarker for cancers, but methods for detecting DNA methylation are time consuming or use chemicals that damage the DNA. A team including researchers from the Tokyo University of Agriculture and Technology developed a technique that detected methylation by measuring how efficiently a controlled enzyme reaction, the polymerase chain reaction (PCR), could copy and elongate two methylated DNA sequences. They demonstrated that, in human-derived genomic DNA, the elongation efficiency of PCR decreased as DNA methylation of the sequences increased. The results suggest that DNA methylation was thwarting the enzyme’s DNA copying activity.

The team concludes that measuring the elongation efficiency of PCR can be used to detect DNA methylation, with potential application in cancer diagnosis.