Kniest dysplasia

Kniest dysplasia is a skeletal disorder that is characterized by short stature, joint disease, and problems with vision and hearing. 

People with Kniest dysplasia are born with a short torso and short arms and legs. Adult height ranges from approximately 42 to 57 inches. Other skeletal problems may include a rounded upper back that also curves to the side (kyphoscoliosis), flattened bones of the spine (platyspondyly), dumbbell-shaped bones in the legs, and inward- and upward-turning feet (clubfeet). A distinguishing feature of Kniest dysplasia is abnormal cartilage. Cartilage is a tough, flexible tissue that makes up much of the skeleton during early development; most cartilage is later converted to bone. People with Kniest dysplasia have tiny holes in their cartilage, which makes the cartilage look like Swiss cheese when seen with medical imaging. 

Individuals with Kniest dysplasia often have distinctive facial features, which include a round, flat face with prominent and wide-set eyes.  Some affected infants are born with an opening in the roof of the mouth (cleft palate). Infants with Kniest dysplasia may also have breathing problems due to a windpipe that is too flexible. Enlarged joints that cause pain and restrict movement are another sign of Kniest dysplasia. These joint problems typically lead to early-onset arthritis. Many people with Kniest dysplasia also have hearing loss and problems with vision, such as severe nearsightedness (myopia) and tearing of the light-sensitive tissue at the back of the eye (retinal detachment).