Angelman Syndrome: (15q11q13) FISH Analysis

Clinical Information

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.

Technical Information

Fluorescence in situ hybridization (FISH) is a molecular cytogenetic technique in which fluorescently labeled DNA probes are hybridized to metaphase spreads or interphase nuclei. FISH should be used in conjunction with G-banded chromosome analysis or microarray. FISH is performed upon request when a specific numerical or structural abnormality or microdeletion is suspected.

FISH is also utilized to confirm microdeletions identified during high resolution chromosome analysis and to aid in identification of abnormal chromosomes. FISH will not detect other known mechanisms of Angelman syndrome including imprinting defects, UPD, or UBE3A sequence variants.

Specimen Requirements

The accepted sample type is 3-4 ml of whole blood collected in a sodium heparin (green top) tube. For newborns and small infants, 2-3 ml of blood in a sodium heparin tube is acceptable. Blood kits are available by request.

Transport Instructions

The blood specimen should be kept at room temperature and sent by courier or overnight mail to arrive at the laboratory the next day. Do not freeze or refrigerate the specimen.