Angelman Syndrome by FISH

Test name:
FISH, Angelman syndrome

Order name:
Angelman syndrome by FISH request

Specimen requirements:
Sodium heparin peripheral blood

Minimum volume:
1mL. 4mL preferred

Storage and stability information:
Room temperature 3 days.

Test performed:
Once per week

Methodology:
Fluorescence in situ hybridization

Reference range:
See lab report

Clinical significance:
Seventy percent of patients with Angelman syndrome have an interstitial deletion of chromosome 15.  Approximately 7% of patients with Angelman syndrome do not have the deletion, but instead have two copies of the 15q11.2q13 critical region that are inherited from the father.  This form of inheritance is known as paternal uniparental disomy.  Another 3% have evidence of normal biparental inheritance of chromosome 15, but have an imprinting mutation.  DNA methylation studies can be performed to detect these abnormalities.  Eleven percent of patients have a mutation in the UBE3A gene and are detected by sequence analysis.  In the remaining patients, the genetic mutation has not been identified. 

CPT codes:
88368 x 3