Phenylketonuria: PAH Sequencing

Turnaround Time

2 weeks

CPT Code(s)

81406

Cost

$1,000

Genes

• Phenylketonuria (PKU)

Phenylketonuria (PKU) is caused by a deficiency of phenylalanine hydroxylase. This deficiency leads to an elevation in the levels of phenylalanine in the brain, blood and other tissues. This condition is treatable with a life long diet low in phenylalanine and is part of all state newborn screening programs. Individuals with PKU have mutations in the PAH gene.

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

Sequencing of the gene will detect mutations in 99% of individuals with PKU.

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.