Neuronal Ceroid Lipofuscinosis 2 (CLN2): TPP1 Sequencing

Turnaround Time

3 weeks

CPT Code(s)

81479

Cost

$1,000

Genes

• Neuronal Ceroid Lipofuscinosis Type 2 (CLN2)

The neuronal ceroid lipofuscinoses (CLN) are a group of conditions that are inherited in an autosomal recessive pattern. CLN2, also known as late-infantile or LICLN, generally begins with the onset of seizures between the ages of 2 to 4 years. Developmental regression follows including speech and motor problems along with cognitive decline. In addition to specific findings on EEG and evoked potentials, neurological deterioration is evidenced by ataxia and myoclonus. Retinal degeneration leads to progressive vision loss and ultimately, blindness. The lipopigment pattern seen in CLN2 under microscopic evaluation is said to be curvilinear. Death usually occurs by 10-15 years of age.

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.