Horizontal gaze palsy with progressive scoliosis

Horizontal gaze palsy with progressive scoliosis (HGPPS) is a disorder that affects the eyes and the spine. Individuals with this condition are unable to move their eyes side-to-side (horizontally) from birth, although the problem may not be diagnosed until later in infancy. As a result, affected individuals must track moving objects by turning their head instead of moving their eyes. Up-and-down (vertical) eye movements are typically normal.

In people with HGPPS, an abnormal side-to-side curvature of the spine (scoliosis) develops between infancy and childhood. It tends to be moderate to severe and worsens over time. The abnormal spine position can be painful and can interfere with movement. In severe cases, it may impede breathing. It may require external support, such as bracing, and is often treated with surgery early in life.

People with HGPPS have structural abnormalities along the midline of the brain that can only be seen with medical imaging. This imaging shows distinctive malformations that include underdevelopment of brain structures called the pons and cerebellar peduncles and a notch or cleft in the midline of the brain. While most people with HGPPS have a normal intellect, mild intellectual disabilities can occur.