Confirm diagnosis in at-risk fetuses or those with ultrasonographic features consistent with achondroplasia.
Polymerase Chain Reaction/Fluorescence Monitoring
Fetal Specimen: Two T-25 flasks at 80% confluency of cultured amniocytes. If the client is unable to culture amniocytes, this can be arranged by contacting ARUP Client Services at (800) 522-2787. Or amniotic fluid.
AND Maternal Specimen: Lavender (EDTA), pink (K2EDTA), or yellow (ACD Solution A or B).
Cultured Amniocytes: Fill flasks with culture media. Transport two T-25 flasks at 80% confluency of cultured amniocytes. Backup cultures must be retained at the client's institution until testing is complete.
OR Amniotic Fluid: Transport 10 mL unspun fluid. (Min: 5 mL)
AND Maternal Specimen: Transport 3 mL whole blood. (Min: 1 mL)
Cultured Amniocytes: CRITICAL ROOM TEMPERATURE. Must be received within 48 hours of shipment due to liability of cells.
Amniotic Fluid: Room temperature.
Maternal Specimen: Room temperature.
Maternal specimen is recommended for proper test interpretation. Order Maternal Cell Contamination, Maternal Specimen. This can be arranged by contacting ARUP genetic counselors at (800) 242-2787 ext. 2141. Patient History Form is available on the ARUP Web site or by contacting ARUP Client Services.
Fetal Specimen: Ambient: 48 hours; Refrigerated: Unacceptable; Frozen: Unacceptable
Maternal Specimen: Ambient: 72 hours; Refrigerated: 1 week; Frozen: Unacceptable
Background information for Achondroplasia (FGFR3) 2 Mutations, Fetal:
Characteristics: Short stature with disproportionately short arms and legs, a large head, usually normal life span and intelligence; increased risk for death in infancy from compression of spinal cord and/or upper airway obstruction.
Inheritance: Autosomal dominant; 80 percent arise from de novo mutations.
Penetrance: 100 percent.
Cause: Pathogenic FGFR3 gene mutation.
Clinical Sensitivity: Two mutations, c.1138G>A and c.1138G>C, in the FGFR3 gene account for greater than 99 percent of cases.
Methodology: PCR and fluorescent hybridization probes.
Analytical Sensitivity and Specificity: Greater than 99 percent.
Limitations: Mutations other than c.1138G>A and c.1138G>C will not be detected. Diagnostic errors can occur due to rare sequence variations.
For quality assurance purposes, ARUP Laboratories will confirm the above result at no charge following delivery. Order Confirmation of Fetal Testing and include a copy of the original fetal report (or the mother's name and date of birth) with the test submission. Please contact an ARUP genetic counselor at (800) 242-2787 extension 2141 prior to specimen submission.
Laboratory Developed Test (LDT)
81401; 81265 Fetal Cell Contamination (FCC)
|Component Test Code*||Component Chart Name||LOINC|
|0050548||Maternal Contamination Study Fetal Spec||59266-7|
|0050612||Maternal Contam Study, Maternal Spec||31208-2|
|0051505||Achondroplasia PCR Fetal Specimen||31208-2|