The relationships between DNA methylation levels and chorionicity in newborn twins
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Date
2015-04-07
Authors
Tran, Terry
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Abstract
Monozygotic (MZ) twins are currently used in epigenetic studies as one homogenous group. However, there are two MZ twin types: dichorionic (DC) and monochorionic (MC). We hypothesize that DCMZ twins are more similar epigenetically, compared to MCMZ twins, due to earlier zygote splitting, a higher degree of birth outcome similarity, or both. We recruited 220 newborn twins and obtained genome-wide DNA methylation profiles for 48 twins. Intraclass correlation coefficients (ICC) and linear mixed models were used to investigate the relationships between DNA methylation levels and chorionicity. DCMZ twins tended to have longer gestational age, larger birth weight, and smaller birth length discordance. DCMZ twins had more similar DNA methylation profiles than MCMZ twins (ICC=0.21 vs. 0.13), after adjusting for birth outcomes. Additionally, we identified 5,170 CpG sites with different DNA methylation levels between DCMZ and MCMZ twins. This study highlights the importance of incorporating chorionicity information in epigenetic twin studies.
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Keywords
DNA Methylation, Twins, Chorionicity, Epigenetics, HumanMethylation450, Birth Weight