Thanatophoric Dysplasia, Types 1 and 2 (FGFR3) 13 Mutations, Fetal
Ordering Recommendation
Rule out thanatophoric dysplasia.
Polymerase Chain Reaction/Fragment Analysis
3-7 days  
New York DOH Approval Status
This test is New York DOH approved.
Specimen Required
Patient Preparation
Fetal Specimen: Two T-25 flasks at 80% confluent of cultured amniocytes. If the client is unable to culture amniocytes, this can be arranged by contacting ARUP Client Services at (800) 522-2787.
Maternal Specimen:
Lavender (EDTA), pink (K2EDTA), or yellow (ACD Solution A or B).  
Specimen Preparation
Cultured amniocytes: Fill flasks with culture media. Transport two T-25 flasks at 80% confluent of cultured amniocytes. Backup cultures must be retained at the client's institution until testing is complete.
Maternal Specimen:
Transport 3 mL whole blood.  
Storage/Transport Temperature
Cultured amniocytes: CRITICAL ROOM TEMPERATURE. Must be received within 48 hours of shipment due to lability of cells.
Maternal Specimen:
Room temperature. Ship with the fetal specimen.  
Unacceptable Conditions
Maternal sample is recommended for proper test interpretation; order Maternal Cell Contamination. Patient History Form is available on the ARUP Web site or by contacting ARUP Client Services.  
Fetal: Ambient: 48 hours; Refrigerated: Unacceptable; Frozen: Unacceptable
: Ambient: 72 hours; Refrigerated: 1 week; Frozen: Unacceptable  
Reference Interval
Interpretive Data
Background information for Thanatophoric Dysplasia, Types 1 and 2 (FGFR3) 13 Mutations, Fetal
Micromelia, macrocephaly, short ribs and a narrow thorax; TD I has bowed femurs and TD II has straight femurs and a cloverleaf skull; death usually occurs from respiratory insufficiency within hours or days of birth.
1 in 20,000 to 50,000 births.
Autosomal dominant; arising from a de novo mutation.
Fibroblast growth factor receptor 3 (FGFR3) gene mutations.
Mutations tested:
c.742C>T (R248C), c.746C>G (S249C), c.1108G>T (G370C), c.1111A>T (S371C), c.1118A>G (Y373C), c.2419T>G (X807G), c.2419T>A (X807R), c.2420G>T (X807L), c.2420G>C (X807S), c.2421A>T (X807C), c.2421A>C (X807C) and c.2421A>G (X807W) for TD I and c.1948A>G (K650E) for TD II.
Clinical Sensitivity and Specificity:
99 percent.
Polymerase chain reaction (PCR) and single nucleotide extension followed by capillary electrophoresis.
Analytic Specificity and Sensitivity:
99 percent.
Mutations other than those targeted in FGFR3 will not be detected; analytic sensitivity may be compromised by rare primer site mutations. 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.

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.
CPT Code(s)
81479; Fetal Cell Contamination (FCC): 81265
Component Test Code*Component Chart NameLOINC
0050548Maternal Contamination Study Fetal Spec31208-2
0050612Maternal Contam Study, Maternal Spec31208-2
0051488Thanatophoric Dysplasia I/II, Fetal Spec 
0051507Thanatophoric Dysplasia I/II 
* 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.
  • Fetal Thanatophoric dysplasia fetal mutation assay
  • FGFR3 fetal mutation assay
  • TD (Thanatophoric Dysplasia, Types 1 & 2 (FGFR3) 13 Mutations, Fetal)