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Table 2 Critical parameters for epigenome-wide association studies

From: Letter to the editor: blood processing and sample storage have negligible effects on methylation

Parameter How to address
Inter-individual variability Sex Appropriate inclusion and exclusion criteria; record information; statistical corrections
Age
Diet and lifestyle
Alcohol consumption
Medication use
Variability in the sample Leukocyte counts and composition Determine leukocyte counts and cell-composition at sample collection and adjust methylation data accordingly
Variability introduced through processing Changes in leukocyte counts with prolonged storage of whole blood Determine leukocyte counts and cell-composition immediately or as soon as possible after sample collection
Efficiency of bisulphite conversion Include commercially available standards in the conversion reaction to determine conversion efficiency and include technical replicates
DNA integrity post-bisulphite conversion Assess DNA integrity post-conversion with a multiplex PCR assay
  1. PCR polymerase-chain reaction