Global DNA (hydroxy)methylation is stable over time under several storage conditions and temperatures

Figures & data

Figure 1. Experimental set up of material stored at different temperatures

EDTA blood of 30 individuals and extracted DNA samples of another 30 individuals were aliquoted and stored at three different temperatures for different time durations as indicated. Blood samples stored at 4°C were stored for 1 month only. Baseline samples were immediately processed and quantified which is why no storage temperature was given (-).

Figure 2. DNA (hydroxy)methylation over time for blood and DNA samples stored at different temperatures

Mean ± SD DNA methylation (upper panel) and hydroxymethylation (lower panel) quantified in samples stored as blood (solid line) or DNA (dashed line).

Figure 3. Effect of freezing and thawing on the stability DNA (hydroxy)methylation

Mean percentage DNA methylation (left) and hydroxymethylation (right) for 0 (fresh material), 1, 2 or 3 freeze-thaw cycles. Error bars represent the standard deviation.

Table 1. Precision results of method validation

Component	DNA concentration (ng/µL)	Within-run CV%	Between-run CV%
5-hmdC/2-dG	27	6.3	6.3
	54	7.6	7.7
5-mdC/2-dG	27	1.7	2.8
	54	1.5	2.5

CV = coefficient of variation