Metachromatic Leukodystrophy: ARSA Sequencing

Turnaround Time

3 weeks

CPT Code(s)

81405

Cost

$1,000

Genes

• Metachromatic Leukodystrophy (MLD)

Metachromatic leukodystrophy is an autosomal recessive condition caused by a deficiency of arylsulfatase A, an enzyme crucial to the breakdown of sulfatides in the body. The accumulation of sulfatides causes demyelination of nerves. Progressive signs of leukodystrophy include a decline in intellectual abilities and motor skills to the extent that affected individuals lose the ability to walk, speak, see, and hear. This condition can present as late-infantile, juvenile or adult forms, and it is more common in people of Israeli or Navajo descent.

Metachromatic leukodystrophy should be considered in any individual with progressive neurological dysfunction and MRI evidence of a leukodystrophy. Diagnosis is typically initially made by enzyme testing. Molecular testing is useful to confirm the diagnosis and to identify the disease causing mutations within a family to allow for carrier testing and prenatal diagnosis.

Sanger Sequencing

The preferred sample type is 3-5 ml of peripheral blood collected in an EDTA (purple top) tube. Extracted DNA, dried blood spots, and saliva are also accepted for this test. Saliva samples must be submitted in an approved saliva kit. Contact the lab to receive a saliva kit or to have one sent to your patient.

The specimen should be kept at room temperature and delivered via overnight shipping. If shipment is delayed by one or two days, the specimen should be refrigerated and shipped at room temperature. Do not freeze the specimen. Samples collected on Friday can be safely designated for Monday delivery.

Prenatal diagnosis is available if the familial mutations are known. Additional fees for cell culture and maternal cell contamination may apply. Maternal cell contamination studies are required for all prenatal molecular tests. Contact the laboratory prior to sending a prenatal specimen.