A fluorescent in situ hybridization (FISH) test is offered to identify the microdeletion on chromosome 17 (p13.3) associated with Miller-Dieker syndrome and isolated lissencephaly.

Individuals with isolated lissencephaly or lissencephaly with seizures, mental retardation and distinct facial features (Miller-Dieker syndrome).

Fluorescence in situ hybridization (FISH) is the application of fluorescently-labeled DNA probes to metaphase chromosomes or interphase nuclei for the detection of chromosome abnormalities such as aneuploidy, structural rearrangements and microdeletions. Approximately 90% of patients with Miller-Dieker syndrome have deletions detected by FISH. The deletion is also found in approximately 33% of patients with isolated lissencephaly.

The assay uses a probe located at 17p13.3 and a chromosome 17 control probe. Analysis is based on fluorescent signals present in 10 to 20 labeled metaphases.

• Blood: Sodium heparin (green top) tubes

            Newborn: minimum 1-2 mL

            Child/Adult: minimum 3-5 mL

• A completed Cytogenetics Requisition Form must accompany specimen.
• Transport at ambient temperature. Specimen cannot be frozen.
• If prenatal testing is required, contact the laboratory regarding specimen requirements.

TURNAROUND TIME: 10 days

CPT CODES: