CST6 and breast cancer: Chimonidou et al. (2013b) used bisulphite conversion and methylation-specific PCR of circDNA to show that the CST6 promoter was methylated in two separate cohorts of breast cancer patients, with methylation found in 14/73 patients (19.2%) in the first cohort, and in 49/123 patients (39.8%) in the second cohort, while none of the 37 healthy individuals tested showed methylation.