Apert Syndrome – FGFR2 Exon 8

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APERT SYNDROME - FGFR2 EXON 8

Gene Symbol: FGFR2 (exon 8 only)

Chromosomal Locus: 10q26

Protein: Fibroblast growth factor receptor 2

Pseudonyms: FGFR2 exon 7 or exon IIIa; Acrocephalosyndactyly, type 1; ACS1; ACS I

TURNAROUND TIME: 10 days

TESTING METHODOLOGY: Polymerase chain reaction (PCR) and DNA Sequencing of exon 8 (aka 7 or IIIc)of the FGFR2 gene.

SPECIMEN REQUIREMENTS:
  • Collect: Prefer two 5ml whole blood EDTA (lavender top) tube.
  • Min. Collection: 0.7 ml whole blood EDTA.
  • Transport: blood EDTA at Room Temp shipped next day air (No Saturday delivery; store specimen refrigerated and ship Monday).
  • Stability: Ambient: up to 7 days; Refrigerated: 2 weeks. Frozen: unacceptable
  • Unacceptable Conditions: Serum. Frozen or severely hemolyzed blood. Clotted blood.

Prenatal testing: Direct: 5ml direct unspun amniotic fluid or 15mg CVS tissue with a backup flask growing. Culture: confluent T25 flask. Maternal blood sample is required for maternal cell contamination studies.

A Molecular Genetics Laboratory Test Requisition must accompany the specimen. Contact the Molecular Laboratory at 918-502-1721 to obtain further information.

Note: Counseling and informed consent are recommended for genetic testing. A consent form is available as a resource but not required.
 
INTERPRETATIVE DATA:
 
Incidence: 1 in 65,000; 4.5% of all craniosynostosis
 
Inheritance: Spontaneous mutation - either c.758C>G (Pro252Arg; aka P250R) or c.755C>G (Ser252Trp; aka S252W) in the FGFR2 gene.
 
Disease Characteristics: features the premature closure of the sutures of the skull which can lead to mental retardation, bulging eyes and head dysmorphology, as well as hand and feet syndactyly ranging from the fusion of several fingers and toes to a flipper like appearance.
 
Molecular Genetic Mechanism: One of two mutations, S252W or P253R, are found in 98% of individuals with Apert Syndrome.
 
 
Clinical Sensitivity: 98%
 
Analytic Sensitivity: 99%
 
Test Limitations: Deletions of exon 8 will not be detected. Rare diagnostic errors can occur due to primer or probe site mutations or rare polymorphisms. Specifically rare cited mutations involving Alu element and de novo insertions.
 
INDICATIONS FOR USE:
  • To determine whether Apert syndrome is responsible for abnormalities in the skull, hands, feet, or eyes.
  • To discriminate between syndromes with overlapping clinical symptoms in an affected individual.
  • Prenatal diagnosis as indicated by abnormal ultrasound findings.
ADDITIONAL RESOURCES:
Gene Home Reference: www.ghr.nlm.nih.gov/gene/FGFR2