Larsen syndrome is a rare genetic disorder that affects bone development throughout the body. The symptoms of Larsen syndrome widely vary from person to person - even if they are related. Usually, infants with Larsen syndrome are born with inward and upward-turning feet. They are also generally born with hip, knee, and elbow dislocations. Affected persons usually have small extra bones located in their wrists and ankles.
Larsen syndrome is related to the filamin B (FLNB) gene. Filamin B is vital to skeletal development while still in the womb. It is expressed in the cell membrane of chondrocytes, which are cartilage-forming cells.
Cartilage is an important structural component for the body and is more flexible than bone. Cartilage is found in many places, such as in joints between bones. Mutations of this gene have been seen in several conditions that affect bones, such as boomerang dysplasia.