The PAX6gene is expressed at high levels in the developing eye and cerebellum and is mutated in patients with autosomal dominant aniridia. We have tested the role of PAX6mutations in three families with Gillespie syndrome, a rare autosomal recessive condition consisting of partial aniridia, cerebellar ataxia, and mental retardation. Single-strand conformational polymorphism analysis of affected individuals revealed no alteration of PAX6sequences. In two families, the disease trait segregates independently from chromosome 11p markers flanking PAX6. We conclude that Gillespie syndrome is genetically distinct from autosomal dominant aniridia.