Sanfilippo Syndrome D (MPS IIID): GNS Sequencing

Turnaround Time

3 weeks

CPT Code(s)

81479

Cost

$1,000

Genes

• Sanfilippo syndrome D (MPS IIID)

Sanfilippo syndrome is caused by a defect in one of four enzymes required for the modification and removal of glucosamine residues from heparan sulfate. A defect in one of these four enzymes (types A-D) results in the accumulation of heparan sulfate in the patient�s cells and organs which overtime leads to the clinical phenotype. Patients with Sanfilippo syndrome experience delayed development with a progressively deteriorating mental status. Behavior and sleep problems are common as well as coarse facial features and stiff joints. The four types of Sanfilippo syndrome (A-D) are clinically indistinguishable, thus enzyme testing is recommended as an initial diagnostic test.

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.