GeneDx :: Tests :: Angelman Syndrome (AS), Angelman-like syndrome (X-Linked Syndromic Mental Retardation, Christianson Type)

301-519-2100 • FAX 301-519-2892 • 207 PERRY PARKWAY GAITHERSBURG, MD 20877

Angelman Syndrome (AS)

UBE3A

Angelman-like syndrome (X-Linked Syndromic Mental Retardation, Christianson Type)

SLC9A6

Angelman syndrome (AS) is a neurological disorder affecting both development and behavior. Individuals with Angelman syndrome exhibit cognitive delays, seizures, ataxia, absence of speech, and characteristic electroencephalogram (EEG) abnormalities. Characteristic behavioral abnormalities include sleep disorders and a happy demeanor with recurrent laughter, smiling and excitability. Similar to those with AS, individuals with Angelman-like syndrome also have mental retardation, ataxia, severe limitations in language and speech, a happy demeanor with frequent smiling or spontaneous laughter, epilepsy, and microcephaly. The X-linked Angelman-like syndrome is primarily found in males, but carrier females occasionally display a mild phenotype that may include learning disabilities.

Among patients with normal methylation patterns, FISH results, and UPD studies, UBE3A mutations are detected by DNA sequencing in 50-80% of familial cases and in 10-44% of de novo cases. Mutations in SLC9A6 are rare in patients with an Angelman-like phenotype; only 4 out of 73 (~6%) families in one study and 1 out of 59 patients/families in another study were found to have an SLC9A6 mutation.

Sequence analysis of the UBE3A and SLC9A6 genes is offered as separate tests. Using genomic DNA obtained from the submitted specimens, bi-directional sequence analysis of the coding exons and corresponding intron/exon boundaries of UBE3A (exons 3-13) or SLC9A6 (exons 1-16) is performed. Targeted array CGH testing (FISHonChipDx) for Angelman syndrome with exon-level coverage of UBE3A is also available as a separate test to detect the large recurrent deletion of the 15q11.2-q13.1 region on the maternal chromosome.

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