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GNAS Related Disorders
Short Description : GNAS Genetic Testing
Also known as : [Albright hereditary osteodystrophy],[McCune-Albright syndrome],[Pseudohypoparathyroidism type Ia],[Pseudopseudohypoparathyroidism]


DNA/RNA
Test performed by: LabPLUS - Dept. Diagnostic Genetics - Molecular Genetics


Referral Requirements

Important Note:

Diagnostic referrals through Specialist Services.

Familial testing only through Genetic Services.

Contact:

Genetic Health Service NZ can be contacted on 0800 476 123.


Specimen Collection
EDTA4 mL Paediatric EDTA Blood (Preferred)
EDTA8 mL Adult EDTA Blood

Note:

For paediatric samples a minimum of 0.5ml blood EDTA can be processed. (Microcollect)

Transport all bloods at room temperature within 24-48 hours. If necessary specimens can be refrigerated overnight for transport at room temperature the following day.

For testing of other sample types please contact the laboratory prior to sending.


Turnaround Time: 13 weeks
Contact Information

Contact Molecular Genetics via:

Lablink                                                     ext 22000

Mark Greenslade (Technical Head)   ext 22010

Pippa Grainger (Section leader)              ext 22014

Email: DGen@adhb.govt.nz




Background Information

The McCune-Albright syndrome, or Albright disease, is disorder of bone, skin, and endocrine gland dysfunction.  It has widespread effects on the body as a result of abnormal functioning hormonal glands including the thyroid, pituitary, adrenal, and sex glands.  This causes bony overgrowth including those of the skull which causes narrowing of the tunnel through which the optic nerve passes.  When the optic nerve is compressed as a result, it can cause blindness.  Hearing may be affected by the same mechanism.  However, all bones of the body are affected causing multiple deformities.  The skin develops large pigmented patches called caf?-au-lait spots.  Often there is considerably asymmetry of lesions and bony overgrowth between the two sides of the body.  Early puberty may occur in both sexes.  The metabolic basis of these effects remains unknown.This is generally not a familial disorder although several large pedigrees of individuals that may have had this disorder have been reported and these suggest autosomal dominant inheritance.  Even though this is generally not a heritable disorder, a single gene ( GNAS )  is involved.  Mutations in GNAS occurs early in development so that only some cells carry the mutant gene.  The variable clinical picture results from the differences in number and location of cells among individuals in whom the mutation happened.  The mutation is seldom passed on to offspring.

Mutations in the GNAS gene also cause Albright hereditary osteodystrophy (AHO), which is characterized by short stature, obesity, unusually short fingers and toes (brachydactyly), ectopic development of bony tissue under the skin, and other skeletal abnormalities. When a mutation that causes AHO is inherited from a person's mother, the affected individual will usually have AHO accompanied by a resistance to multiple hormones (a condition called pseudohypoparathyroidism type Ia, or PHPIa). A paternally-inherited mutation can result in AHO without endocrine problems; this form of the condition is also called pseudopseudohypoparathyroidism (PPHP).


Molecular genetic testing for GNAS is available.

For more information about the Molecular Genetics service:

Molecular Genetics information page


Last updated at 15:49:04 22/03/2021