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Table 2 Characteristics summary of GSMSs based on whole blood samples

From: DNA methylation changes of whole blood cells in response to active smoking exposure in adults: a systematic review of DNA methylation studies

First author (year)

Country

Sample

Measurementa

Smoking indicatorsb

Gene(s)

Main findinge

Size

Male

Age mean

(n)

(%)

(year)

Zhang, (2014) [8]

Germany

3588

44.4

61.7

MALDI-TOF

Current/former/never smoker (PY, ND, TQ)

F2RL3

F2RL3 methylation strongly decreased with current smoking intensity and with lifetime cumulative smoking, and reached a plateau at higher current and cumulative smoking intensity. Methylation levels increased with time since cessation, but the time for full recovery was more than 20 years.

Shenker, (2013) [7]

UK

81/180c

81.5/0

NRd

BPP

Current/former/never smoker (SD, CL)

AHRR, 2q37, 6p21

Combining four gene loci of AHRR, 2q37, and 6p21 into a single methylation index provided high positive, predictive, and sensitivity values for predicting former smoking status in both test (n = 81, AUC = 0.82) and validation (n = 180, AUC = 0.83) sample sets.

Breitling, (2012) [23]

Germany

1100

66.6

58.0

MALDI-TOF

Continuing smoker/quit after acute event/quit before acute event/never smoking

F2RL3

F2RL3 were significantly associated with smoking history of patients with CHD (median methylation intensities at CpG_4, continuing smoker = 0.53; quit after acute event = 0.51; quit before acute event = 0.66; never smoking = 0.74) (p < 0.001).

  1. a MALDI-TOF Sequenom matrix-assisted laser desorption ionization time-of-flight mass spectrometry, BPP Bisulphite pyrosequencing
  2. b PY pack-year, SD smoking duration, ND numbers of cigarettes daily, TQ time of quitting smoking, CL serum cotinine levels
  3. cThe exploratory and validation analysis included 81 and 180 participants, respectively
  4. dNot reported
  5. e AUC area under the curve, CHD coronary heart disease