Pelizaeus-Merzbacher Disease, Spastic Paraplegia: PLP1 Sequencing

Test Information

PLP1 sequencing is a molecular test used to identify variants in the gene associated with Pelizaeus-Merzbacher Disease, Spastic Paraplegia.

Turnaround Time

6 weeks

CPT Code(s)

81405

Cost

$700

Genes

  • PLP1

Clinical Information

Pelizaeus-Merzbacher is an X-linked hypomyelinative leukodystrophy and progressive neurologic condition presenting in infancy. Typical findings include abnormal eye movement, hypotonia, head tremor, ataxia, spasticity, quadri- and paraplegia, involuntary movements and cognitive deficiencies. Carrier females are usually asymptomatic or may have mild neurologic findings in adulthood, but some severely affected females have been reported as well.

Indications

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.

Methodology

Sanger Sequencing

Detection

Sequencing of the PLP1 gene will detect a mutation in approximately 15-25% of affected males. 50-60% of males will have dosage alterations detected by MLPA anlaysis. The majority of these are duplications rather than deletions.

Specimen Requirements

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.

Transport Instructions

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 Testing Information

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.

Have Questions? Need Support?

Call our laboratory at 1-800-473-9411 or contact one of our Laboratory Genetic Counselors for assistance.
Robin Fletcher, MS, CGC
Falecia Thomas, MS, CGC
Alex Finley, MS, CGC

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