ARX-Related Spectrum of X-Linked Intellectual Disability (XLID): ARX Sequencing

Turnaround Time

6 weeks

CPT Code(s)

81404

Cost

$1,000

Genes

• X-linked Intellectual Disability (XLID)

ARX is an X-linked disorder that can include non-syndromic intellectual disability or a broader phenotype including intellectual disability of West syndrome (infantile spasms), Partington syndrome (dystonic movements, ataxia and seizures) or X-linked hydrocephalus with ambiguous genitalia. ARX is localized to Xp21.1. Two mutations, a 24bp duplication and a 21bp insertion, in exon 2 of ARX account for a significant proportion of the alterations within the gene. Carrier females have no discernable phenotype.

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.