GLI3-related disorders : GLI3 Sequencing

Test Information

GLI3 sequencing is a molecular test used to identify variants in the gene associated with GLI3-related disorders including Greig Cephalopolysyndactyly and Pallister-Hall syndrome.

Turnaround Time

6 weeks

CPT Code(s)

81479

Cost

$1,500

Genes

Clinical Information

Major finding of Greig Cephalopolysyndactyly include macrocephaly, ocular hypertelorism, preaxial polydactyly and cutaneous syndactyly. Preaxial polydactyly must be present on at least one limb, but may include multiple limbs and affect hands or feet. Postaxial polydactyly has also been reported. Patients on the severe end of the spectrum may have seizures, hydrocephalus, and intellectual disability in addition to the above findings.

Pallister-Hall syndrome is also caused by mutations in GLI3. Pallister-Hall is characterized by multiple anomalies with a spectrum of severity reported. the most common anomalies are polydactyly, bifid epiglottis, larynotracheal cleft and hypothalamic hamartoma. Less common findings include renal and genitourinary abnormalities, imperforate anus, pulmonary segmentation and other skeletal anomalies.

Both of these disorders are inherited in an autosomal dominant pattern.

Mutations in GLI3 have also been associated with isolated polydactyly.

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 GLI3 will identify the underlying genetic defect in approximately 70% of cases of Greig Cephalopolysyndactyly.

Approximately 95% of patients with Pallister-Hall syndrome will have a mutation in GLI3.

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

Sanger Sequencing
One Mother's Story

One Mother's Story

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