Angelman Syndrome


Molecular Genetics Clinical Laboratory- Angelman Syndrome

INDICATIONS FOR TESTING:
Angelman syndrome presents in early childhood with hypotonia followed by motor and intellectual retardation. Affected children are ataxic, epileptic, have absence of speech, and an unusual facies characterized by a large mandible and an open-mouthed expression. Patients demonstrate excessive laughter, an occipital groove, a facility for protruding the tongue, abnormal choroidal pigmentation, and characteristic electroencephalogram (EEG) discharges. This disorder is caused by deletions of chromosome 15q11-q12 (~70% of cases) by uniparental paternal disomy of chromosome 15 (~5%), by mutations in the UBE3A gene (~20%) or by unknown etiology (~5%).

TESTING OFFERED:
Testing is done using molecular cytogenetic FISH analysis with SNRPN, & D15S10 probes and a routine karyotype in the Cytogenetics Laboratory, as well as SNRPN gene methylation testing and molecular polymorphism analysis in the Molecular Genetic Laboratory. Specimens from parents are requested for UPD analysis.

TURN-AROUND TIME:
Most testing is completed within a time of 21 days following specimen receipt. Prenatal testing is usually completed within 7 days from specimen receipt.

SPECIMEN REQUIREMENTS:
All specimens should be kept at room temperature and shipped overnight in an insulated container.

Adults and Children:
Two tubes of whole blood are required.
1) A tube of 4 cc whole blood collected in an EDTA (lavender top) tube is preferred. Whole blood collected with other anticoagulants is acceptable but not preferred.

2) A second tube with 3 cc of blood collected in sodium heparin (green top) tube is required. Lithium heparin and other anticoagulants are not acceptable.

Neonates:
The minimum specimen is 0.5 cc whole blood in EDTA tube and 2.0 cc of blood in a sodium heparin (green top) tube.

Prenatal:
Prenatal testing is usually not indicated since most cases of Angelman syndrome, except those with chromosomal rearrangements, are de novo and have a low risk for future pregnancies. Genetic counseling is advised.

COST:
Charges are available upon request.

FOR MORE INFORMATION, PLEASE CONTACT:
Phone:
(727) 767-8985 (Laboratory)
            (727) 767-8611 (Director)
Fax: (727) 767-8367
E-mail: muellert@allkids.org