Table 4

Differential methylation analysis of the eight selected BW-MVPs using the Infinium and DBS data

Infinium

DBS

CpG number

Gene

Mean heavy co-twins^a

Mean light co-twins^a

Mean difference

P^b

Mean heavy co-twins^c

Mean light co-twins^c

Mean difference

P^b

cg14123607

APBA1

0.22 ± 0.07

0.15 ± 0.07

0.07 ± 0.05

0.0008

0.09 ± 0.05

0.09 ± 0.05

0.006 ± 0.04

0.30

cg12170649

APPL2

0.81 ± 0.04

0.86 ± 0.02

-0.06 ± 0.05

<0.0001

0.97 ± 0.02

0.97 ± 0.02

-0.002 ± 0.02

0.86

cg26404226

NA

0.50 ± 0.05

0.56 ± 0.07

-0.05 ± 0.04

<0.0001

0.35 ± 0.08

0.36 ± 0.06

-0.01 ± 0.05

0.46

cg15487251

IGF2BP2^d

0.53 ± 0.05

0.58 ± 0.04

-0.05 ± 0.05

0.002^e

0.65 ± 0.05

0.64 ± 0.06

0.01 ± 0.03

0.04

cg10362113

PAPOLA^d

0.83 ± 0.08

0.77 ± 0.06

0.06 ± 0.07

0.008

0.98 ± 0.04

0.99 ± 0.03

-0.01 ± 0.05

0.50

cg02409150

PHKG2

0.88 ± 0.05

0.94 ± 0.03

-0.06 ± 0.05

<0.0001

0.93 ± 0.02

0.93 ± 0.02

-0.006 ± 0.03

0.43

cg15049370

PPARGC1B^d

0.70 ± 0.06

0.77 ± 0.07

-0.07 ± 0.07

0.002^e

0.96 ± 0.01

0.97 ± 0.02

-0.007 ± 0.02

0.23

cg22768222

RUNX2

0.37 ± 0.07

0.31 ± 0.05

0.06 ± 0.07

0.008

0.21 ± 0.03

0.21 ± 0.03

0.001 ± 0.05

1.00

Results of the Wilcoxon signed-rank test of the 8 selected MVPs performed on the Infinium and the DBS data in the 16 MZ twins discordant for birth weight (pair 1 was excluded) are presented. ^aInfinium data are expressed as mean β-value ± SD. ^bHeavy versus light calculated using a Wilcoxon signed-rank test. ^cDBS data are expressed as mean methylation level ± SD, where the methylation level is calculated by dividing the number of reads in which the particular CpG is methylated by the total number of sequenced reads. ^dInfinium and DBS data were adjusted for buccal content (using PTPN7) and the adjusted values are presented. ^eAlso significant without adjusting for buccal marker. Mean difference = Heavy co-twin - Light co-twin. BW-MVP, birth weight-associated methylation variable position; DBS, deep bisulfite sequencing; MZ, monozygotic.

Souren et al. Genome Biology 2013 14:R44   doi:10.1186/gb-2013-14-5-r44