Fragile X Syndrome is a rare developmental disorder and the most common cause of inherited intellectual disability. Tetra Discovery Partners, building on research about the role the enzyme PDE4 plays in the disease, is developing an experimental drug to inhibit its activity. We spoke to Mark Gurney, chairman and CEO of Tetra Discovery Partners, about Fragile X, the potential of its PDE4 inhibitor, and why this drug may have therapeutic benefit in a range of neurodegenerative diseases.