Ordering Recommendation

Prenatal testing for hemophilia A caused by a familial F8 gene intron 22-A or intron 1 inversion.

Mnemonic

F8 INV FE

Methodology

Inverse Polymerase Chain Reaction/Electrophoresis

Performed

Varies

Reported

10 days; if culture is required, an additional 1 to 2 weeks is required for processing time.

New York DOH Approval Status

This test is New York DOH approved.

Specimen Required

Patient Preparation
Collect

Fetal Cultured Amniocytes or Cultured CVS
AND Maternal Whole Blood Specimen:
Lavender (EDTA) or yellow (ACD Solution A or B).

Specimen Preparation

Cultured Amniocytes or Cultured CVS: Transfer cultured amniocytes or cultured CVS to two T-25 flasks at 80 percent confluence: (Min: one T-25 flask at 80 percent confluence). Backup cultures must be retained at the client's institution until testing is complete. If ARUP receives a sample below the minimum confluence, CG GRW&SND (0040182) will be added on by ARUP, and additional charges will apply. If clients are unable to culture specimens, CG GRW&SND should be added to initial order.
Maternal Whole Blood Specimen:
Transport 2 mL whole blood (Min: 1 mL).

Storage/Transport Temperature

Cultured Amniocytes or Cultured CVS: CRITICAL ROOM TEMPERATURE. Must be received within 48 hours of collection due to viability of cells.
Maternal Whole Blood Specimen:
Room temperature.

Unacceptable Conditions
Remarks
Stability

Cultured Amniocytes or Cultured CVS: Room temperature: 48 hours; Refrigerated: Unacceptable; Frozen: Unacceptable
Maternal Whole Blood Specimen:
Room temperature: 7 days; Refrigerated: 1 month; Frozen: Unacceptable

Reference Interval

Interpretive Data

Background Information for Hemophilia A (F8) 2 Inversions, Fetal:
Characteristics:
Severe deficiency of factor VIII clotting activity leading to spontaneous joint or deep muscle bleeding.  Moderate to mild deficiency is associated with prolonged bleeding after tooth extractions, surgery, or injuries and recurrent or delayed wound healing.
Incidence: 1 in 4,000-5,000 live male births worldwide, rare in females.
Inheritance: X-linked recessive. Of simplex cases, 85 percent of mothers are carriers and 10-15 percent of boys have a de novo mutation.
Penetrance: 100 percent in males and 10 percent in females.
Cause: Deleterious F8 gene mutations.
Clinical Sensitivity: 51 percent of mutations causing severe hemophilia A are detected by F8 inversion testing. This assay does not detect F8 mutations associated with mild or moderate hemophilia A in males.
Methodology: Intron 22-A and intron 1 inversions detected by inverse PCR and electrophoresis.
Analytical Sensitivity and Specificity: 99 percent.
Limitations: Diagnostic errors can occur due to rare sequence variations.  F8 mutations, other than the F8 intron 22-A and intron 1 inversions, will not be detected.

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.

Compliance Category

Laboratory Developed Test (LDT)

Note

Hotline History

N/A

CPT Codes

81403; 81265 Fetal Cell Contamination (FCC)

Components

Component Test Code* Component Chart Name LOINC
0050548 Maternal Contamination Study Fetal Spec 59266-7
0050612 Maternal Contam Study, Maternal Spec 66746-9
2001758 F8 INV FE Specimen 31208-2
2001761 Hemophilia A (F8) Inversions Interp 82343-5
* 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.

Aliases

  • Fetal Carrier Detection of Hemophilia A
  • Fetal DNA Analysis for Hemophilia A
  • Fetal Factor VIII Deficiency assay
  • Fetal Hemophilia A Carrier Detection and Prenatal Diagnosis
Hemophilia A (F8) 2 Inversions, Fetal