CASK-related X-linked intellectual disability (XLID) : CASK Sequencing

Test Information

CASK sequencing is a molecular test used to identify variants in the gene associated with CASK-related X-linked intellectual disability (XLID).

Turnaround Time

6 weeks

CPT Code(s)

81479

Cost

$1,500

Genes

Clinical Information

There is a phenotypic spectrum associated with mutations in the CASK gene. This includes affected males and females with mild to severe intellectual disability, with or without dysmorphic features, and unaffected carrier females.

Ocular abnormalities, specifically nystagmus and strabismus, appear to be common findings, including in some carrier females with normal intelligence. Other neurological findings such as gait abnormalities, seizures, and a resting tremor have also been described in individuals with CASK mutations.

An FG-like phenotype in one family has also been associated with mutations in this gene.

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

Specimen Requirements

5 to 7 ml of peripheral blood collected in an EDTA (lavender top) tube is the preferred specimen type. The minimal blood needed for reliable DNA isolation is 3 ml. Extracted DNA, dried blood spots, and saliva are also accepted for this test.

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
Kellie Walden, MS, CGC

Molecular Testing, Sanger Sequencing
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