| Definition: |
A syndrome characterized by a variable phenotype primarily including seizures, gingival overgrowth, a prominent mandible or cherubism, and mental deterioration that has_material_basis_in homozygous or compound heterozygous mutation in the TBC1D2B gene on chromosome 15q24. Other more variable features include coarse facial features, optic atrophy, sensorineural hearing loss, ataxia, hypotonia, delayed development or developmental regression, cerebellar or cerebral atrophy, and enlarged brain ventricles. |