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Prader-Willi/Angelman Syndromes

Item Value
Approval req'd? No
Available Stat? No
Test code PWA
Performed by Medical Genomics - Molecular Diagnostics
In House Availability Run 1x per week as needed, Wednesday or Friday, day shift only
Prader-Willi: Methylation sensitive Southern blot
Angelman: Methylation sensitive Southern blot
Collection Instructions If collecting in citrate, check the expiration date on the label of the blue top vacutainer before drawing the patient.

Do not collect sample in heparin. Keep sample refrigerated for overnight or longer storage.

For UCSF Samples (from remote sites) Click here for sample collection instructions

For NON-UCSF Samples Click here for Requisition form & Account set-up instructions. Note we only do institutional billing.
Container type Lavender top , Blue (citrate) and Yellow (ACD) tops acceptable
Amount to Collect 3 mL blood
Sample type EDTA Whole blood, Cultured amniocytes, Cultured chorionic villi
Preferred volume 3 mL blood
Min. Volume 2 mL blood
UCSF Rejection Criteria Samples collected in outdated blue top vacutainer.
Processing notes Do not centrifuge the specimen. Store at room temperature. Refrigerated samples are acceptable.
Normal range Negative
Synonyms Happy puppet syndrome;
Stability Blood samples are stable for up to one week.
Turn around times 10-14 days
Additional information An interpretation of this test by a laboratory physician will automatically be performed and billed for separately.

A normal fetus inherits one copy of chromosome 15 from each parent. If the fetus inherits two paternal chromosome 15's because of uniparental disomy or carries a maternal chromosomal 15 deletion then the Angelman (Happy Puppet) Syndrome results.

If the fetus inherits only the maternal chromosome as a result of paternal chromosome deletion, then the Prader-Willi Syndrome results.

This assay identifies approximately 95 99% of Prader-Willi patients and 80 78% of Angelman patients; in the remaining cases of Angelman syndrome DNA sequencing of the UBE3A gene may uncover point mutations.

If a mutation is detected it is recommended that the patient seek genetic counseling.
CPT coding 81331
LOINC code 36915-7
LDT or Mod FDA? Yes
Last Updated 1/22/2014 8:59:49 AM
Entry Number 770
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