Mucolipidosis III Gamma: GNPTG Sequencing

Test Information

GNPTG sequencing is a molecular test used to identify variants in the gene associated with Mucolipidosis III Gamma .

Turnaround Time

6 weeks

CPT Code(s)

81479

Cost

$1,000

Genes

  • GNPTG

Clinical Information

Mucolipidosis II (ML II), also known as I-Cell disease, and Mucolipidosis IIIA (ML IIIA), also known as Pseudo-Hurler Polydystrophy, are lysosomal storage disorders caused by a deficiency of N-acetylglucosamine-1-phosphotransferase (NAPT). ML II is associated with a more severe course including growth failure and failure to thrive, severe developmental delay, coarse facial features, skeletal anomalies and frequent upper respiratory infections. ML II is often lethal in childhood. ML IIIA is associated with a similar, but milder course with a wider spectrum of features and severity. In ML II and ML IIIA, lysosomal hydrolase enzymes are not properly targeted to the lysosome. Therefore, the enzyme activity of multiple lysosomal hydrolases is increased in plasma and other body fluids.

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 gene will detect mutations in >95% of individuals with MLII/IIIA. GNPTG sequencing can be requested separately or reflexed if GNPTAB sequencing is normal.

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

Mother and son

A Rare Beauty

The lobby of the JC Self Research Institute at GGC was transformed into a garden – of sorts. The art exhibit titled ‘Rare Roses’ consisted of 12 paintings that depict real roses with genetic variations. The series was created by Nicole Shannon, an artist from Greenville. Nicole was inspired by her son, who has a rare genetic disorder, and other individuals with genetic differences. Quinn, now 4, was born with a myriad of health issues and ...

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