Ornithine Transcarbamylase Deficiency: OTC Sequencing

Turnaround Time

6 weeks

CPT Code(s)

81405

Cost

$1,000

Genes

• Ornithine transcarbamylase (OTC) deficiency

Biochemical abnormalities associated with OTC deficiency include hyperammonemia, low citrulline and arginine, and elevated urinary orotic acid. Since OTC is an X-linked disorder, male infants are primarily affected usually presenting in the first few days of life with lethargy, anorexia, seizures, neurologic posturing, abnormal breathing, and coma related to cerebral edema. Long-term prognosis depends on the initial duration of the hyperammonemia. About 15% of carrier females will develop hyperammonemia, which may or may not require chronic medical management.

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.