Prof Claudia Bagni leads new study on FXS and smell

In the beautiful region of Lazio, Italy, a team of dedicated researchers is exploring a largely understudied side of Fragile X Syndrome – the sense of smell. The work is led by Prof. Claudia Bagni, who conducts her research between the University of Rome Tor Vergata and the University of Lausanne, and who also serves on FraXI’s Board of Advisors.

For a full article on this study, please click here.

Supported by the Telethon Foundation (Telethon–Cariplo 2025 call), Prof. Bagni’s team is studying so-called “dark genes”, genes that remain poorly understood, some of which are linked to olfactory receptors. Their goal is to better understand why individuals with Fragile X Syndrome (FXS) often experience smells differently, including how pleasant or unpleasant odours feel to them, the so-called hedonic value. 

As Prof. Bagni explains, some of these “dark genes” directly involved in smell perception are controlled by FMRP. When FMRP is not present, as in FXS, the olfactory perception is different. By studying these in depth, the team hopes to open the way to new sensory-based approaches that could improve quality of life, particularly in areas such as nutrition, environment, and social interaction.

There is great value in exploring how the sense of smell differs in those with FXS. Smell is a ‘fundamental’ sense which is important for us to establish relationships with other people and ourselves. Smells are closely tied with memories- some smells (like that of our pets, for example!) conjure happy memories while some odours (like the smell of medicine, for example!) can remind us of a bad time when we were ill. We also use our sense of smell to read our surroundings- it can even be a useful tool to warn us of danger (such as smelling smoke). But the clinical assessment of smell is still quite rare to come by, resulting in a rather narrow understanding of how its role varies from one neurodevelopmental condition to another. 

The study reports: 

“Among the various forms of sensory atypia, olfactory atypia is the least characterized in neurodevelopmental disorders. Even less explored is the hedonic component of the olfactory experience that makes the perception of a smell pleasant or unpleasant, which profoundly influences the way in which individuals interact with their environment and modulate their behavior.” 

Prof Claudia Bagni shares that the idea to explore the sense of smell in FXS came from a discussion that she had with a mother of a child living with FXS, who had noticed that her son perceived certain smells differently and found some of them pleasant and others unpleasant. “From there, I began discussing smell with other families and found that many had noticed the same thing! This is the beginning of our hypothesis that these children may have a unique olfactory sensitivity,” says Prof Bagni. 

Together with her co-researchers, Marianna Pompili, Giorgia Pedini and others, Prof Bagni is  looking at the olfactory system in the mouse model for FXS and importantly, promoting an immediate clinical impact of their findings. “We are also conducting a parallel study on the olfactory profile of individuals with Fragile X syndrome and autism,” she adds. “We are convinced that these two complementary projects represent a concrete example of how basic research and clinical practice, working side by side, can build an innovative and integrated path toward new therapeutic opportunities.” 

Prof Bagni welcomes anyone who wishes to get in touch to contact her via email: claudia.bagni@unil.ch