Alternative Name
GNAS, guanine nucleotide-binding protein (alpha-subunit)
Test Description

Bi-directional sequencing of exons 8 and 9 of the GNAS gene to detect mutation hot spots in codons R201 and Q227.

Clinical Significance

Guanine nucleotide-binding protein/alpha-subunit (GNAS) gene is mutated, over-expressed and/or amplified in a number of diseases. GNAS mutations have been reported in 28% of pituitary gland tumors, 9% of pancreatic tumors, 6% of parathyroid tumors, 5% of thyroid tumors, 6% of soft tissue tumors, and 4% of colorectal cancers. Mutations have also been reported in 45% of fibrous dysplasia of bone and is used to distinguish this condition from ossifying fibroma. Testing for GNAS mutations can aid in targeted drug therapy decisions.

Specimen Requirements

Peripheral blood: 5 mL in EDTA tube. Bone marrow: 2 mL in EDTA tube. FFPE tissue: Paraffin block is preferred. Alternatively, send 1 H&E slide plus 5-10 unstained slides cut at 5 or more microns. Please use positively-charged slides and 10% NBF fixative. Do not use zinc fixatives. Fresh tissue:  0.5 - 1 cm3 in RPMI.

Storage and Transportation

Use cold pack for transport, making sure cold pack is not in direct contact with specimen.

CPT Code(s)*
Turnaround Time

14 days

Level of Service

*The CPT codes provided with our test descriptions are based on AMA guidelines and are for informational purposes only. Correct CPT coding is the sole responsibility of the billing party. Please direct any questions regarding coding to the payor being billed.