Gillespie syndrome, also called aniridia, cerebellar ataxia and mental deficiency,[1][2][3] is a rare genetic disorder.

The disorder is characterized by partial aniridia (meaning that part of the iris is missing), ataxia (motor and coordination problems), and, in most cases, intellectual disability.

[6][7] Mariën P did not support the prevailing view of a global mental retardation as a cardinal feature of Gillespie syndrome but primarily reflect cerebellar induced neurobehavioral dysfunctions following disruption of the cerebrocerebellar anatomical circuitry that closely resembles the "cerebellar cognitive and affective syndrome" (CeCAS).

[citation needed] PAX6 gene analysis can also be helpful to distinguish between autosomal dominant aniridia and Gillespie syndrome.

[2][8] To elucidate the underlying genetic defects karyotyping and the search for de novo translocations especially of chromosome X and 11 should be performed.