Table 2 Intraclass correlation coefficient (ICC) and 95% confidence intervals for global methylation measures (technical replicates, PBMC) and different thresholds for CpG site selection.

From: Reliability of DNA methylation measures from dried blood spots and mononuclear cells using the HumanMethylation450k BeadArray

Global measure

Mean β-valuea

ICCs [95% CI]

All CpG sites

Sites with ICC > 0.3

Sites with ICC > 0.5

Median (all)

0.67

0.74 [0.61–0.81]

0.77 [0.63–0.82]

0.75 [0.62–0.80]

Median (promoters)

0.10

0.75 [0.62–0.81]

0.84 [0.69–0.89]

0.88 [0.75–0.92]

Median (islands)

0.08

0.68 [0.56–0.75]

0.82 [0.70–0.87]

0.88 [0.75–0.92]

Median (shores)

0.52

0.82 [0.69–0.86]

0.76 [0.62–0.82]

0.75 [0.62–0.81]

Median (shelves)

0.88

0.76 [0.63–0.82]

0.78 [0.64–0.83]

0.78 [0.64–0.83]

  1. aThe mean β-value was calculated as the mean global measure across all samples.
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