Dwarfism Panel (FGFR 3)

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DWARFISM PANEL (FGFR 3)

Tests performed in the Panel: Achondroplasia (ACH) and Hypochondroplasia (HCH)

Gene Symbol: FGFR3; see individual test pages for additional information.
 
TURNAROUND TIME: 10 days
 
TESTING METHODOLOGY: Polymerase chain reaction (PCR) and DNA Sequencing of the region of exon 10 encompassing the most common HCH mutations. Detection of a G380R (c.1138G>A or G>C) mutation by PCR and restriction enzyme digestion.
 
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 regular next day air (No Saturday delivery; store specimen at 4°C 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: unknown; estimated to be 1 in 15,000 - 40, 000.
 
Inheritance: may be spontaneous or inherited in an autosomal dominant manner
 
Disease Characteristics: Both syndromes are characterized by abnormal bone growth that results in short stature with disproportionately short arms and legs, & macrocephaly. Other symptoms may include hypotonia in infancy; broad, short hands and feet; or mild joint laxity depending on the diagnosis. In both, intelligence and life span are usually normal.
 
 
Clinical Sensitivity: please see individual test pages
 
Test Limitations: Mutations lying outside the tested regions (roughly 5-10% of cases of hypochondroplasia) will not be detected. Rare diagnostic errors can occur due to primer / probe site mutations or rare polymorphisms.
 
INDICATIONS FOR USE:
  • To confirm the nature of the dwarfism in an affected individual.
  • To evaluate fetuses with abnormal ultrasound findings for the possibility of spontaneous ACH
  • To evaluate Individuals at risk who wish prenatal diagnosis.
ADDITIONAL RESOURCES:
OMIM Achondroplasia - www.omim.org/entry/100800
OMIM Hypochondroplasia: www.omim.org/entry/146000