Angelman syndrome is characterized by severe motor and intellectual disability, absence of speech, ataxia and a characteristic open-mouthed face. Other features such as hypotonia, epilepsy and excessive laughter help in the diagnosis of the condition. Mutations in the ubiquitin-protein ligase E3A gene (UBE3A) located on chromosome 15 are known to be associated with a subset of Angelman syndrome cases. UBE3A is specifically imprinted in the brain where it is only expressed from the maternal allele. In individuals that retain the clinical diagnosis of Angelman syndrome following normal methylation studies, UBE3A sequencing studies should be given strong consideration.