Typical of epigenome scans, this one doesn’t make any clear links between methylation states and any diseases, though the researchers make a couple plausible connections, for example, suggesting that demethylation affects the AHRR gene’s role in fibroblast apoptosis in lungs. In any case, the data will be very useful to epigeneticists in general.
Researchers from the NIH National Institute of Environmental Health Sciences, the Norwegian Institute of Public Health, the Haukeland University Hospital in Bergen, Norway, Duke University, and several other institutions published the paper online at the NIEHS website under the title “450K Epigenome-Wide Scan Identifies Differential DNA Methylation in Newborns Related to Maternal Smoking During Pregnancy.”
In one approach that avoids some of the ambiguities of surveys, the researchers use continine levels in the blood of pregnant moms to ascertain smoking behavior in the main subject group, which they drew from the Norwegian Mother and Child Cohort Study. But they used self reports to determine smoking behavior in the 36 people who were part of the replication study, and drew these subjects from the Newborn Epigenetics STudy, known as NEST.
The investigators identified 26 CpGs as significantly changed, when comparing non-smoking moms to smokers, and they were mostly associated with four genes, which they narrowed to three. Comparing these CpGs to the replication study’s epigenomes — of smokers and non-smokers — the team verified its choices.
- Growth factor independent 1 transcription repressor (GFI1)
- Aryl-hydrocarbon receptor repressor (AHRR)
- Cytochrome P450 isoform CYP1A1
Both AHRR and CYP1A1 are involved in detoxification, and a previous epigenome scan of smokers and non-smokers also flagged AHRR. So, this study seems to show for the first time that this response occurs in fetuses.
GFI1 is mostly known as a development gene — it’s involved with the inner ear, for example, and it influences apoptosis, differentiation, and more. It appears to do this at least partly through roles in histone modification and RNA splicing.
So, the authors suggest, this gene at least has the potential to be broadly influential in the development of a human being, possibly enough to explain some health effects.
[The ashtray pic above is by Flicker user cipher, and it's used here under a CreativeCommons license.]
Joubert BR, Håberg SE, Nilsen RM, Wang X, Vollset SE, Murphy SK, Huang Z, Hoyo C, Midttun O, Cupul-Uicab LA, Ueland PM, Wu MC, Nystad W, Bell DA, Peddada SD, & London SJ (2012). 450K Epigenome-Wide Scan Identifies Differential DNA Methylation in Newborns Related to Maternal Smoking During Pregnancy. Environmental health perspectives PMID: 22851337