Lab Dept:

Anatomic Pathology

Test Name:

ALEXANDER DISEASE (GFAP) SEQUENCING

General Information

Lab Order Codes:

ALEX

Synonyms:

GFAP Sequencing

CPT Codes:

81405 – Molecular pathology Level 6

Test Includes:

Sequencing of all 9 exons in the GFAP gene.

Logistics

Test Indications:

Confirm a clinical diagnosis; differentiate Alexander disease from Canavan disease.

Alexander disease (AD) is a progressive disorder of the white matter of the central nervous system (CNS). The three types of AD are categorized by age of onset: infantile, juvenile, and adult. Affected infants develop a megalencephalic leukodystrophy, seizures, spasticity, ataxia, and psychomotor retardation. Infantile AD frequently leads to death within a decade after the diagnosis. Juvenile and adult forms of AD have a more slowly progressive course and are characterized by ataxia, bulbar signs and spasticity. Rosenthal fibers, observed in the astrocytes of affected individuals upon autopsy, are a hallmark feature of AD. These cytoplasmic inclusions are made up of glial acidic fibrillary protein (GFAP) and small heat-shock protein.

Lab Testing Sections:

Anatomic Pathology – Sendouts

Referred to:

GeneDx (GDX Test #: 218)

Phone Numbers:

MIN Lab: 612-813-6280

STP Lab: 651-220-6550

Test Availability:

Daily, 24 hours

Turnaround Time:

Results are reported in 8 weeks

Special Instructions:

A complete GeneDx request form is required. Please send with the patient or sample to the laboratory.

Specimen

Specimen Type:

Whole blood

Container:

Lavender top (EDTA) tube

Alternate specimens: Buccal brushes (GeneDx kit is required) for age 6 months and older.

Draw Volume:

5 mL (Minimum: 1 mL) blood

Processed Volume:

Same as Draw Volume

Collection:

Routine venipuncture

Special Processing:

Lab Staff: Do Not Centrifuge. Blood specimen should remain in the original collection container. Store and ship at ambient temperature.

Buccal Brush: Send with GeneDx kit.

Patient Preparation:

None

Sample Rejection:

Mislabeled or unlabeled specimens

Interpretive

Reference Range:

Negative

Critical Values:

N/A

Limitations:

N/A

Methodology:

Bi-directional Sequence analysis

References:

GeneDx April 2010
(301) 519-2100 • FAX (301) 519-2892