Twin birth changes DNA methylation of subsequent siblings

Area of Science:

• Epigenetics
• Human Genetics
• Developmental Biology

Background:

• DNA methylation patterns are crucial for gene regulation and cellular function.
• Sibling DNA methylation correlations can provide insights into shared genetic and environmental influences.
• The impact of twin births on the intrauterine environment and subsequent sibling epigenetics remains underexplored.

Purpose of the Study:

• To investigate whether twin births alter DNA methylation patterns in subsequent siblings.
• To compare DNA methylation correlations between siblings born before (BT), after (AT), and on either side (B/AT) of a twin birth.
• To identify specific genomic regions and pathways affected by this phenomenon.

Main Methods:

• Utilized whole blood DNA methylation data from siblings in Australian and Korean twin and family studies.
• Employed the HumanMethylation450 array for genome-wide methylation profiling.
• Performed comparative analyses of methylation means and correlations across different sibling birth order groups (BT, B/AT, AT).

Main Results:

• Significantly higher DNA methylation correlation was observed in siblings born after a twin birth (r_AT=0.46) compared to those born before (r_BT=-0.003).
• No significant correlation in DNA methylation was found for siblings born on either side of a twin birth (r_BAT=0.08).
• Differential methylation correlations were identified for 15 probes (P<10^-7), with top probes enriched in cell signaling and breast cancer regulation pathways.

Conclusions:

• Twin births can alter the intrauterine environment, leading to correlated DNA methylation patterns in siblings born subsequently.
• These findings suggest a potential epigenetic legacy of twin pregnancies on later-born siblings.
• Further research is warranted to elucidate the mechanisms linking twin births to altered sibling DNA methylation.