The hands and feet appear large, but the digits are short, broad and stubby. Elbow extension is restricted but of little functional significance. Excessive lumbar lordosis and pelvic tilt cause a waddling gait. Stenosis of the lumbar spine, prolapse of the intervertebral discs, osteophytes and deformed, vertebral bodies may compress the spinal cord and nerve roots. Adult height ranges from 42 to 56 inches.
Spontaneous mutations occur is unclear.
Elbow may have flexion contracture. Radial head sometimes dislocated. Varus-valgus laxity and hyperextension in childhood. Lumbar stenosis in adults may produce motor weakness in ankles. Cervical or thoracic stenosis may cause hyperreflexia.