A new preprint suggests that some of the earliest signs of Prader–Willi syndrome (PWS) may actually begin before a baby is born — not just in the brain after birth, as long believed. This new research, carried out in mice, looks at what signs of PWS are hidden in the placenta before the baby is born.
Prader–Willi syndrome is a rare genetic condition caused by a loss of information on the 15th chromosome. These particular genes are known to be important for brain development and for regulating things like appetite and metabolism. Because of this, most research has focused on what happens in the brain after birth.
But this new study asked a different question: Are these genes also active in the placenta — the organ that feeds and supports the developing baby during pregnancy?
🔍 Key Findings
1. PWS‑related genes are active in the placenta
The researchers discovered that many of the genes linked to PWS are switched on in the mouse placenta. This means the placenta may play a bigger role in the early stages of the condition than scientists previously realised.
2. Two genes are especially active in placental blood‑vessel cells
Two gene messages — Necdin and Sngh14 — were found to be particularly active in endothelial cells. These are the cells that line the tiny blood vessels where the mother’s blood and the baby’s blood come very close together. This area acts like a busy marketplace, allowing oxygen and nutrients to pass from mother to baby.
Put simply, these PWS‑related genes are switched on in the very cells that help control how well the baby receives essential nutrients during pregnancy.
3. Loss of these genes reduces key placental cells
In mice missing the paternal PWS genes, the number of endothelial cells in this nutrient‑exchange zone dropped by about 25%. The babies still grew, but this reduction hints that the placenta may not function quite as efficiently.
What This Could Mean for Early Development and Future Research
Even small changes in how the placenta is built or how well it works could influence how the baby’s brain and metabolism develop. This might help explain why babies with PWS often have low muscle tone and feeding difficulties right from birth.
These findings widen the lens on PWS. Instead of thinking of it only as a brain‑based condition that shows up after birth, this research suggests that the earliest roots may form during pregnancy. If future studies confirm this in humans, it could pave the way for:
- earlier detection
- better understanding of early symptoms
- potential future treatments that support placental health
As this research is a preprint, it means it hasn’t yet been reviewed by other scientists. The results are therefore very fresh, but they offer an intriguing new direction for understanding PWS. To read the preprint yourself check it out here.