Freeman Sheldon Syndrome, or Whistling Face Syndrome is a rare genetic disorder resulting in a small “whistling” mouth, a flat mask-like face, clubfeet, joint contractures, and muscle weakness.
The syndrome is related to Arthrogryposis and Clubfoot. Affected individuals have joint contractures that restrict movement and function. These contractures lead to deformities of the hand, foot, and digits (fingers and toes).
Freeman Sheldon Syndrome is a rare disorder caused by mutation in the MYH3 gene, which codes for a skeletal muscle myosin protein. Myosin proteins are involved with the transport of materials inside and out of cells, as well as cell movement. Myosin, along with actin, are the components that make up muscle fibers. Mutations in the MYH3 gene interfere with normal muscle contraction during fetal development. This results in the muscle contractures and skeletal abnormalities that manifest in the syndrome.