FG Syndrome, FGS1 (MED12) R961W Mutation (INACTIVE as of 05/15/17)
Ordering Recommendation

Diagnostic testing and carrier screening for FGS1.

Polymerase Chain Reaction/Fluorescence Monitoring
7-10 days
New York DOH Approval Status
Specimens from New York clients will be sent out to a New York DOH approved laboratory, if possible.
ARUP Consult®
Disease Topics
Specimen Required
Patient Preparation
Lavender (EDTA), pink (K2EDTA), or yellow (ACD Solution A or B). 
Specimen Preparation
Transport 3 mL whole blood. (Min: 1 mL) 
Storage/Transport Temperature
Unacceptable Conditions
Ambient: 72 hours; Refrigerated: 1 week; Frozen: Unacceptable 
Reference Interval
Interpretive Data
Background Information for FG Syndrome, FGS1 (MED12) R961W Mutation
Mental retardation, congenital hypotonia, constipation/anal anomalies, characteristic face, brain anomalies, behavioral issues and extreme clinical variability.
Incidence: Estimated at 1 in 15,000.
Inheritance: X-linked dominant with reduced penetrance for MED12 gene mutations.
Cause: At least seven X-linked loci have been associated with FG syndrome. The deleterious p.R961W (c.2881C>T) MED12 gene mutation is causative for FG cases localized to Xq13 (FGS1 locus).
Penetrance: Believed 100 percent in males; variable in females.
Clinical Sensitivity: Approximately 7 percent for FG syndrome.
Methodology: Polymerase chain reaction and fluorescence monitoring.
Analytical Sensitivity and Specificity: 99 percent.
Limitations:Diagnostic errors can occur due to rare sequence variations.MED12 gene mutations, other than R961W, and mutations in other causative genes, will not be detected.

This test is performed pursuant to an agreement with Roche Molecular Systems, Inc.

Compliance Statement C: The performance characteristics of this test were validated by ARUP Laboratories. The U.S. Food and Drug Administration (FDA) has not approved or cleared this test. However, FDA approval or clearance is currently not required for clinical use of this test. The results are not intended to be used as the sole means for clinical diagnosis or patient management decisions. ARUP is authorized under Clinical Laboratory Improvement Amendments (CLIA) and by all states to perform high-complexity testing. Counseling and informed consent are recommended for genetic testing. Consent forms are available online.

Component Test Code*Component Chart NameLOINC
0051753FG Syndrome, FGS1 (MED12) R961W Mutation
2002914FG Syndrome Specimen
* Component test codes cannot be used to order tests. The information provided here is not sufficient for interface builds; for a complete test mix, please click the sidebar link to access the Interface Map.
  • FG Syndrome type 1
  • FGS1
  • MED12 (R961W)