Gillespie syndrome

Gillespie syndrome is a disorder that involves eye abnormalities, weak muscle tone from birth (congenital hypotonia), problems with balance and coordinating movements (ataxia), and mild to moderate intellectual disability.

Gillespie syndrome is characterized by underdevelopment (hypoplasia) of the colored part of the eye (the iris). In most affected individuals, part of the iris is missing (partial aniridia) in both eyes. In addition, the irises have a characteristic uneven pattern known as "scalloping" at the inner (pupillary) edge. The pupils are enlarged (dilated) and are fixed, which means they do not get smaller (constrict) in response to light. These abnormalities are thought to result from problems in the development or maintenance of the tiny muscles that allow the pupil to contract (sphincter pupillae). The eye abnormalities can cause blurry vision (reduced visual acuity) and increased sensitivity to light (photophobia). Rapid, involuntary eye movements (nystagmus) can also occur in Gillespie syndrome.

The balance and movement problems in Gillespie syndrome result from hypoplasia of the cerebellum, which is the part of the brain that coordinates movement. This abnormality can cause hypotonia and delayed development of motor skills such as walking. In addition, difficulty controlling the muscles of the mouth can lead to delayed speech development. The difficulties with coordination generally become noticeable in early childhood when the individual is learning these skills. People with Gillespie syndrome usually continue to have an unsteady pattern of walking (gait) and speech problems throughout life.

Other features of Gillespie syndrome can include abnormalities in the bones of the spine (vertebrae) and malformations of the heart.