Aniridia-cerebellar ataxia-intellectual disability syndrome

Aniridia-cerebellar ataxia-intellectual disability syndrome (also known as Gillespie syndrome) is an extremely rare genetic disorder characterized by the triad of partial or total aniridia (absence of the iris of the eye), cerebellar ataxia (impaired coordination due to underdevelopment of the cerebellum), and intellectual disability. The condition is typically present from birth or early infancy, with affected individuals showing congenital bilateral aniridia that is usually partial and non-progressive, distinguishing it from isolated aniridia caused by PAX6 mutations. The cerebellar involvement manifests as hypotonia (reduced muscle tone) in infancy, followed by progressive or non-progressive cerebellar ataxia affecting balance, coordination, and gait. Intellectual disability ranges from mild to severe. The syndrome primarily affects the eyes, the central nervous system (particularly the cerebellum), and cognitive development. Ocular findings include the characteristic fixed, dilated pupils with scalloped remnants of iris tissue, which is a distinctive feature of this condition. Some patients may also exhibit additional features such as ptosis or other minor anomalies. Gillespie syndrome has been associated with mutations in the ITPR1 gene (encoding inositol 1,4,5-trisphosphate receptor type 1) and, in some cases, with PAX6 mutations, though the genetic basis remains heterogeneous. Both autosomal recessive and autosomal dominant inheritance patterns have been reported. There is currently no cure for this condition; management is supportive and multidisciplinary, involving ophthalmologic care (including protection from light sensitivity and visual aids), physical and occupational therapy for ataxia, and educational support for intellectual disability.

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