Decreased Placental Methylation at the H19/IGF2 Imprinting Control Region is Associated with Normotensive Intrauterine Growth Restriction but not Preeclampsia

Bourque, D.K.; Avila, L.; Peñaherrera, M.; von Dadelszen, P.; Robinson, W.P.

doi:10.1016/j.placenta.2009.12.003

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Volume 31, Issue 3 , Pages 197-202, March 2010

Decreased Placental Methylation at the H19/IGF2 Imprinting Control Region is Associated with Normotensive Intrauterine Growth Restriction but not Preeclampsia

D.K. Bourque
- Department of Medical Genetics, University of British Columbia, Vancouver, BC, Canada
- Child & Family Research Institute, University of British Columbia, Vancouver, BC, Canada
L. Avila
- Department of Medical Genetics, University of British Columbia, Vancouver, BC, Canada
- Child & Family Research Institute, University of British Columbia, Vancouver, BC, Canada
M. Peñaherrera
- Department of Medical Genetics, University of British Columbia, Vancouver, BC, Canada
- Child & Family Research Institute, University of British Columbia, Vancouver, BC, Canada
P. von Dadelszen
- Child & Family Research Institute, University of British Columbia, Vancouver, BC, Canada
- Department of Obstetrics and Gynaecology, Division of Maternal-Fetal Medicine, University of British Columbia, Vancouver, BC, Canada
W.P. Robinson
- Department of Medical Genetics, University of British Columbia, Vancouver, BC, Canada
- Child & Family Research Institute, University of British Columbia, Vancouver, BC, Canada
- Corresponding author. Department of Medical Genetics, University of British Columbia, Child & Family Research Institute, 950 West 28th Avenue, Vancouver, BC V5Z 4H4, Canada. Tel.: +1 604 875 3229.

Accepted 5 December 2009. published online 11 January 2010.

Abstract

Many genes exhibiting genomic imprinting, parent-of-origin differences in gene expression, are involved in regulating placental and fetal growth. The goal of the present study was to assess whether abnormal regulation of imprinted genes is associated with intrauterine growth restriction (IUGR) and/or preeclampsia (PET).

Methods

Genomic DNA was extracted from at least two whole villi samples from control (N=22), IUGR (N=13), PET (N=17), and PET+IUGR (N=21) placentas. Methylation was assessed using the Illumina GoldenGate Methylation Cancer Panel I array and Pyrosequencing and MS-SNuPE assays.

Results

The 11p15.5 ICR1 (associated with H19 and IGF2) methylation showed considerable intra-placental variability. Nonetheless, average methylation at this site was significantly decreased in normotensive IUGR placentas (p<0.001), but not in any other group. Methylation at ICR2 (KvDMR1; associated with CDKN1C and other maternally expressed 11p15.5 genes) was not significantly altered in any group and no significant changes in expression levels were observed in the genes controlled by this region. There were no significant methylation changes observed in any candidate imprinted gene evaluated by the Illumina array. LINE-1 methylation, a marker of whole genome methylation, was also similar in all groups.

Conclusions

Reduced methylation of ICR1 is associated with normotensive IUGR but not IUGR associated with preeclampsia, suggesting a different etiology of IUGR in this group. A reduction in placental IGF2 could be an adaptive response to restrict fetal growth in the presence of abnormal placentation or a response to poor fetal growth itself.

Keywords: Methylation, IGF2, 11p15.5, H19, Placenta, IUGR, Imprinting, Preeclampsia