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Table 1 Sample characteristics

From: Novel DNA methylation signatures of tobacco smoking with trans-ethnic effects

Cohorta

Sample size

Smoking statusb

Sex

Age (years)

BMI

Ethnicityc

S (n)

F (n)

NS (n)

F (%)

M (%)

Discovery stage

TwinsUK

407

23

237

147

100

0

64 ± 8

26.8 ± 5.0

White British

NSHD

236

23

75

138

60

40

63 ± 0.5

27.9 ± 4.7

White British

NCDS1

235

53

118

64

53

47

45

25.6 ± 4.3

White British

NCDS2

294

125

87

82

51

49

45

25.8 ± 4.3

White British

BCS70

235

45

126

64

57

43

46

26.6 ± 5.0

White British

Replication stage

SHS

2325

893

648

748

59

41

55 ± 6

29.6 ± 3.0

American Indian

GENOA

1100

179

255

666

71

29

56 ± 10

31 ± 6.6

African-American

  1. aCohort abbreviations: TwinsUK: https://twinsuk.ac.uk/, NSHD: MRC National Survey of Health and Development, NCDS: National Child Development Study (NCDS1 = selected to minimize data missingness, but not selected for specific exposures and trait outcomes. NCDS2 = selected for extremes of child and adulthood adversity), BCS70: 1970 British Cohort Study, SHS: Strong Heart Study. GENOA: Genetic Epidemiology Network of Arteriopathy
  2. bSmoking status, age and BMI are obtained at the date of blood draw for DNA methylation profiling. Smoking status (S = smoker, F = former smoker, NS = never smoker) is determined through questionnaires
  3. cParticipants from the UK population cohorts are predominantly “White British.” NCDS2 includes one individual who did not identify as “White British” (“Mixed”). BCS70 includes three individuals who did not identify as “White British” (one “White Other”, one “White and Asian” and one “Other Ethnic Group”)