Fat dads must not be blamed for their children's health problems

The relationship between the parental genomes in terms of the future growth and development of their offspring is not critical. For the majority of the genome the tissue-specific gene expression and epigenetic status is shared between the parents equally, with both alleles contributing without parental bias. For a very small number of genes the rules change and control of expression is restricted to a specific, parentally derived allele, a phenomenon known as genomic imprinting. The insulin-like growth factor 2 (Igf2/IGF2) is a robustly imprinted gene, important for fetal growth in both mice and humans. In utero IGF2 exhibits paternal expression, which is controlled by several mechanisms, including the maternally expressing untranslated H19 gene. In the study by Soubry et al., a correlation is drawn between the IGF2 methylation status in fetal cord blood leucocytes, and the obesity status of the father from whom the active IGF2 allele is derived through his sperm. These data imply that paternal obesity affects the normal IGF2 methylation in the sperm and this in turn alters the expression of IGF2 in the baby

Insulin-like growth factor axis in pregnancies affected by fetal growth disorders

Background: Insulin-like growth factors 1 and 2 (IGF1 and IGF2) and their binding proteins (IGFBPs) are expressed in the placenta and known to regulate fetal growth. DNA methylation is an epigenetic mechanism which involves addition of methyl group to a cytosine base in the DNA forming a methylated cytosine-phosphate-guanine (CpG) dinucleotide which is known to silence gene expression. This silences gene expression, potentially altering the expression of IGFs and their binding proteins. This study investigates the relationship between DNA methylation of components of the IGF axis in the placenta and disorders in fetal growth. Placental samples were obtained from cord insertions immediately after delivery from appropriate, small (defined as birthweight the 90th percentile for the gestation [LGA]) neonates. Placental DNA methylation, mRNA expression and protein levels of components of the IGF axis were determined by pyrosequencing, rtPCR and Western blotting. Results: In the placenta from small for gestational age (SGA) neonates (n = 16), mRNA and protein levels of IGF1 were lower and of IGFBPs (1, 2, 3, 4 and 7) were higher (p < 0.05) compared to appropriately grown neonates (n = 37). In contrast, in the placenta from large for gestational age (LGA) neonates (n = 20), mRNA and protein levels of IGF1 was not different and those of IGFBPs (1, 2, 3 and 4) were lower (p < 0.05) compared to appropriately grown neonates. Compared to appropriately grown neonates, CpG methylation of the promoter regions of IGF1 was higher in SGA neonates. The CpG methylation of the promoter regions of IGFBP1, IGFBP2, IGFBP3, IGFBP4 and IGFBP7 was lower in the placenta from SGA neonates as compared to appropriately grown neonates, but was unchanged in the placenta from LGA neonates. Conclusions: Our results suggest that changes in CpG methylation contribute to the changes in gene expression of components of the IGF axis in fetal growth disorders. Differential methylation of the IGF1 gene and its binding proteins is likely to play a role in the pathogenesis of SGA neonates

Paternal Allele of IGF2 Gene Haplotype CTG Is Associated With Fetal and Placental Growth in Japanese

http://journals.lww.com/pedresearch/pages/default.aspx This is a non-final version of an article published in final form in (Pediatric Research, 66(2), pp.135-139, 2009)IGF-II associates with feto-placental growth in rodent and human. determined three tag-single nucleotide polymorphisms (SNPs) to investigate haplotype frequency of IGF2 relative to size at birth in 134 healthy Japanese infants. In addition, a total of 276 healthy infants were investigated to determine whether common genetic variation of IGF2 might contribute to feto-placental growth Using haplotype analysis. Further, quantitative methylation analysis of the IGF2/HI9 wits performed using the MassARRAY Compact system. In the initial study,. the frequency of haplotype CTG front the paternal allele in small for date (SFD) infants was significantly higher than that in non-SFD infants (p = 0.03). In second Study, the CTG haplotype infants exhibited significantly lower birth length, weight. and placental weight Compared with non-CTG infants. Further, the number of infants less than - 1,5 SD (SD) birth weight in CTG haplotype was higher than those if non-CTG infants. There was no significant difference in the methylation status of HI9/IGF2 in the two haplotypes. In conclusion, inheriting the IGF2 CTG haplotype front I paternal allele results ill reduced feto-placental growth. but it is not associated with the methylation Status of IGF2/HI9. (Pediatr Res 66: 135-139, 2009