DNA methylation of IGF2, GNASAS, INSIGF and LEP and being born small for gestational age

Figures & data

Table 1 Characteristics at birth and pregnancy

Characteristics		SGA	AGA	p value1
Number of individuals	N	38	75
Male	%	39.5	44.0	0.65
Adult height	SDS2 (SD)	−1.02 (0.99)	−0.17 (0.97)	3.3 × 10^−5
At Birth
Gestational age at birth	weeks (SD)	30.6 (1.1)	30.1 (1.5)	0.053
Birth weight	SDS3 (SD)	−1.86 (0.50)	0.31 (0.73)	1.1 × 10−31
Birth head circumference	SDS (SD)	−1.34 (0.79)	0.20 (0.92)	4.1 × 10^−13
Birth length	SDS (SD)	−1.83 (0.87)	0.19 (1.12)	3.3 × 10^−13
Obstetric data
First child (parity)	%	68%	52%	0.097
Maternal age	years (SD)	27.8 (4.8)	27.9 (5.9)	0.92
Problematic obstetric history4	%	18.4	17.3	0.89
Socio-economic status5	SES	3.53 (1.50)	3.59 (1.55)	0.82
Maternal height	cm (SD)	165.6 (5.4)	167.3 (6.1)	0.14
Maternal diabetes mellitus	%	5.3	4.0	0.57
Chorioamnionitis6	%	5.3	25.3	0.009
Smoking during pregnancy	%	28.9	35.7	0.029
Pre-existing hypertension	%	10.7	2.7	0.08
Preeclampsia	%	65.8	10.7	3.4×10^−11

1 p value resulting from an unpaired t-test between the SGA and AGA groups.

2 Standard deviation score from the reference population mean.

3 The birth weight in grams (SD) for the SGA and AGA groups were 963(149) and 1508(301) respectively.

4 Percentage of mothers with previous pregnancies and/or births with complications.

5 Socio-economic status of the family given on a 1–6 scale, with 1 being the poorest score and 6 being the highest score.

6 Intrauterine infection followed by a prolonged rupture of the membrane and preterm labor.

Table 2 Methylation difference between SGA and AGA

	AGA (SD)	SGA - AGA1	p value2
IGF2	48.5% (3.5)	−0.2%	0.81
GNASAS	47.5% (4.6)	−0.7%	0.41
INSIGF	79.4% (3.2)	−0.2%	0.78
LEP	25.7% (5.3)	−1.3%	0.24

1 The difference in DNA methylation between the small for gestational age and appropriate for gestational age groups. A negative difference means that the SGA group has a lower methylation level.

2 A two-sided p value resulting from a linear mixed model corrected for the correlation between individual CpG dinucleotides, bisulfite batch and sex between the SGA and AGA groups.

Table 3 The relation between DNA methylation and risk factors

	IGF2		GNASAS		INSIGF		LEP
	β1	p2	β	p	β	p	β	p
Preeclampsia	0.8%	0.34	0.9%	0.29	0.0%	0.99	−0.2%	0.88
Chorioamnionitis	0.8%	0.36	0.8%	0.42	0.5%	0.52	2.8%	0.033
Smoking3	−1.5%	0.054	−0.9%	0.29	−0.4%	0.53	−1.9%	0.98

1 The β from a linear mixed model corrected for the correlation between individual CpG dinucleotides, bisulfite batch and sex. The investigated variable was entered as a fixed effect.

2 A two-sided p value resulting from a linear mixed model corrected for the correlation between individual CpG dinucleotides, bisulfite batch and sex.

3 Smoking during pregnancy by the mother.