Scientists have identified a gene which, when missing or impaired, can cause obesity, behavioural problems and, in mothers, postnatal depression | This may have wider implications for the treatment of postnatal depression, with a study in mice suggesting that oxytocin may alleviate symptoms.

From the article: Obesity and postnatal depression are significant global health problems. Postnatal depression affects more than one in 10 women within a year of giving birth and is linked to an increased risk of suicide, which accounts for as many as one in five maternal deaths in high income countries. Meanwhile, obesity has more than doubled in adults since 1990 and quadrupled in adolescents, according to the World Health Organization.

While investigating two boys from different families with severe obesity, anxiety, autism, and behavioural problems triggered by sounds or smells, a [team](https://www.cell.com/cell/fulltext/S0092-8674(24)00641-X) led by scientists at the University of Cambridge, UK, and Baylor College of Medicine, Houston, USA, discovered that the boys were missing a single gene, known as TRPC5, which sits on the X chromosome.

Further investigation revealed that both boys inherited the gene deletion from their mothers, who were missing the gene on one of their X chromosomes. The mothers also had obesity, but in addition had experienced postnatal depression.

To test if it was the TRPC5 gene that was causing the problems in the boys and their mothers, the researchers turned to animal models, genetically-engineering mice with a defective version of the gene (Trpc5 in mice).

Male mice with this defective gene displayed the same problems as the boys, including weight gain, anxiety, a dislike of social interactions, and aggressive behaviour. Female mice displayed the same behaviours, but when they became mothers, they also displayed depressive behaviour and impaired maternal care. Interestingly, male mice and female mice who were not mothers but carried the mutation did not show depression-like behaviour.

Dr Yong Xu, Associate Director for Basic Sciences at the USDA/ARS Children’s Nutrition Research Center at Baylor College of Medicine, said: “What we saw in those mice was quite remarkable. They displayed very similar behaviours to those seen in people missing the TRPC5 gene, which in mothers included signs of depression and a difficulty caring for their babies. This shows us that this gene is causing these behaviours.”