Confirm diagnosis in at-risk fetuses or those with ultrasonographic features consistent with thanatophoric dysplasia type 1 or type 2.
Polymerase Chain Reaction/Fragment Analysis
New York DOH Approval Status
Cultured Amniocytes, Cultured CVS, or Amniotic fluid (direct).
Maternal Whole Blood Specimen: Lavender (EDTA), pink (K2EDTA), or yellow (ACD Solution A or B).
Cultured Amniocytes or Cultured CVS: Transfer cultured amniocytes or cultured CVS to two T-25 flasks at 80% confluence. (Min: one T-25 flask at 80% confluence). Backup cultures must be retained at the client's institution until testing is complete. If the client is unable to culture amniocytes or CVS, this can be arranged by contacting ARUP Client Services at (800) 522-2787. Please contact an ARUP genetic counselor at (800) 242-2787 ext. 2141 prior to test submission.
Amniotic Fluid (direct): 10 milliliters
Maternal Whole Blood Specimen: Transport 2 mL whole blood (Min: 1mL).
Cultured Amniocytes or Cultured CVS: CRITICAL ROOM TEMPERATURE. Must be received within 48 hours of collection due to viability of cells.
Amniotic fluid (direct): Ship room temperature.
Maternal Whole Blood Specimen: Room temperature.
Please contact an ARUP genetic counselor at (800) 242-2787 ext. 2141 prior to sample submission. Patient History Form is available on the ARUP Web site or by contacting ARUP Client Services at (800) 522-2787.
Cultured Amniocytes or Cultured CVS: Room temperature: 48 hours; Refrigerated: Unacceptable; Frozen: Unacceptable
Amniotic Fluid (direct): Room temperature: 48 hours; Refrigerated: 72 hours; Frozen: Unacceptable
Maternal Whole Blood Specimen: Room temperature: 7 days; Refrigerated: 1 month; Frozen: Unacceptable
Background information for Thanatophoric Dysplasia, Types 1 and 2 (FGFR3) 13 Mutations, Fetal
Characteristics: 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.
Incidence: 1 in 20,000 to 50,000 births.
Inheritance: Autosomal dominant; arising from a de novo mutation.
Cause: 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.
Methodology: Polymerase chain reaction (PCR) and single nucleotide extension followed by capillary electrophoresis.
Analytic Specificity and Sensitivity: 99 percent.
Limitations: 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 was developed and its performance characteristics determined by ARUP Laboratories. It has not been cleared or approved by the US Food and Drug Administration. This test was performed in a CLIA certified laboratory and is intended for clinical purposes.
Counseling and informed consent are recommended for genetic testing. Consent forms are available online.
Laboratory Developed Test (LDT)
81479; 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|
|0051488||Thanatophoric Dysplasia I/II, Fetal Spec||31208-2|
|0051507||Thanatophoric Dysplasia I/II||75391-3|
- Fetal Thanatophoric dysplasia fetal mutation assay
- FGFR3 fetal mutation assay