University of Helsinki: Alcohol alters gene activity in an embryo’s first cells
- Nordic Alcohol and Drug Policy Network
- 1 day ago
- 3 min read
23.06.2025 - Exposure to alcohol during the first weeks of embryonic development changes how genes work and how cells handle their metabolism. Experiments in culture dishes showed that the very first nerve cells are the most sensitive to alcohol. The finding supports the current advice to stop drinking as soon as pregnancy is being planned.
During gastrulation, embryonic cells differentiate with tight control into the germ layers, endoderm, mesoderm and ectoderm, from which every human tissue and organ eventually develops. Developmental biologist Lewis Wolpert once said, “The most important event in your life is not birth, marriage or death, but gastrulation.” This happens in the fifth week of pregnancy, when many women do not yet know they are pregnant.
According to estimates from the Finnish Association on Intellectual and Developmental Disabilities, 600 to 3 000 children in Finland are born each year with permanent damage caused by alcohol. Because diagnosing these conditions is difficult, the true number is unknown.
Researchers at the University of Helsinki, together with colleagues at the University of Eastern Finland, have now examined alcohol’s impact on this early stage of development, which is hard to study directly in humans.
In the study, pluripotent embryonic stem cells were grown in culture and guided to become each of the three germ layers. The cells were then exposed to two alcohol concentrations. The lower level corresponded to under one per mille (below 0.1 percent blood alcohol) and the higher to over three per mille (above 0.3 percent). The team then analysed how alcohol affected gene expression, the epigenetic marks that regulate genes and the cells’ metabolism.
The higher exposure caused more changes than the lower one, and a clear dose response was seen in gene activity and metabolism. The most marked metabolic changes occurred in the methionine cycle.
“The methionine cycle produces the vital methyl groups that bind to DNA and influence gene regulation. The changes we observed highlight the importance of this epigenetic control in the disturbances caused by alcohol,” says doctoral researcher Essi Wallén.
Earliest nerve cells are the most sensitive
The strongest alcohol-related changes were found in ectodermal cells, which later form the nervous system and brain. Prenatal alcohol exposure is already known to be a major cause of disorders in nervous system development.
“Many of the developmentally important genes that changed in our study have previously been linked to prenatal alcohol exposure and its features, such as defects in the heart and corpus callosum and to holoprosencephaly, the incomplete separation of the forebrain,” says Docent Nina Kaminen Ahola, who led the research.
Some of the developmental disorders caused by alcohol may arise in the very first weeks of pregnancy, when even small changes in gene activity can alter development. This supports the current recommendation to stop drinking when planning pregnancy. More research is needed, however, to clarify how the cell model and alcohol levels used here relate to real exposure.
This work is part of a larger programme that investigates the mechanisms by which alcohol affects early development and health later in life. Prenatal alcohol exposure causes a range of developmental disorders collectively known as fetal alcohol spectrum disorders (FASD).
Read the study
