FISH ANALYSIS, MILLER-DIEKER SYNDROME, ISOLATED LISSENCEPHALY and SUBCORTICAL BAND HETEROTOPIA
Chromosomal Locus: 17p13.3
Pseudonyms: PAFAH1B1-Associated Lissencephaly/Subcortical Band Heterotopia, 17-Linked Subcortical Band Heterotopia, Isolated 17-Linked Lissencephaly
TURNAROUND TIME: 7 to 10 days
TESTING METHODOLOGY: Fluorescence in situ hybridization
- Collect: 3-5 mL peripheral blood in sodium heparin (green) for children and adults; 1-2 mL peripheral blood in sodium heparin (green) for newborns
- Min. Collection: 1 mL for newborns; 2 mL for children and adults
- Transport: peripheral blood in sodium heparin (green) at 20-25°C
- Stability: Ambient: 24 hours; Refrigerated: 72 hours; Frozen: unacceptable
- Unacceptable Conditions: Frozen or clotted specimens; specimens in anticoagulants other than sodium heparin.
Test Summary: Test can detect microdeletions of the LIS1 gene on chromosome 17. Miller-Dieker syndrome is associated with deletions that include both LIS1 and YWHAE in 17p13.3. Approximately 54% of patients with isolated lissencephaly have a deletion of LIS1 detectable by FISH. Mosaic deletions of LIS1 have been identified in patients with subcortical band heterotopia.
Methods: A dual-color FISH analysis performed on metaphase cells using a probe for the LIS1 gene in 17p13.3 and a chromosome 17 control probe; analysis of 10 metaphase cells and 20 interphase cells.
Indications for Use:
- Patients suspected of having Miller-Dieker syndrome on the basis of clinical findings such as lissencephaly, seizures, developmental delay, and distinct facial features.
- Patients with isolated lissencephaly
- Patients with subcortical band heterotopia.