Larsen syndrome is a disorder that affects the development of bones throughout the body. The signs and symptoms of Larsen syndrome vary widely even within the same family. Affected individuals are usually born with inward- and upward-turning feet (clubfeet) and dislocations of the hips, knees, and elbows. They generally have small extra bones in their wrists and ankles that are visible on x-ray images. The tips of their fingers, especially the thumbs, are typically blunt and square-shaped (spatulate).
Mutations in the FLNB gene cause Larsen syndrome. Larsen syndrome occurs in approximately 1 in 100,000 newborns.