Test Directory
Factor VIII (8) Deletion/Duplication Analysis by MLPA
Justification
Hemophilia A is due to mutations in the F8 gene. Knowing the mutation can inform likelihood of inhibitor development, bleeding severity, family planning, and pregnancy and neonatal management. Over 5% of severe hemophilia A cases are due to large deletion or duplication variants which are very difficult to detect via sequencing.
Specimen Requirements
| Sample Type | Volume Required | Minimum Volume | Stability | |
|---|---|---|---|---|
| PREFERRED | EDTA Whole Blood | 3mL | 1mL | Room Temp.: 1 month
Refrigerated: 1 month Frozen (-20C): 2 weeks Frozen (-80C): 6 months |
| ALTERNATIVE | Cheek swab | 2 swab | - | Room Temp.: 1 month
Refrigerated: 1 month |
| REJECTION CRITERIA | Sample contamination; sample compromised |
| SPECIAL INSTRUCTIONS | - |
General Information
| METHODOLOGY | MLPA |
| STAT TAT | < 48 hours (M-F) |
| STAT TAT Performance | > 90% of results released in 48 hours |
| ROUTINE TAT | < 5 days (M-F) |
| ALTERNATIVE NAMES | Hemophilia A, FVIII (8) copy number variant (CNV) analysis |
| DESCRIPTION | This test looks for deletions or duplications within the F8 gene by multiplex ligation-dependent probe amplification (MLPA), a method with much higher resolution than next-generation sequencing or microarrays. |
| LIMITATIONS | This test detects deletions and duplications but not balanced structural variants (i.e., inversions, insertions and translocations). This test does not detect the recurrent inversions in intron 1 or intron 22 that account for about half of severe hemophilia A cases. This test requires two consecutive probes indicating a deletion or duplication to make a CNV call. |
| NORMAL RANGE | Interpretation: Negative |
| ASSOCIATED TESTING | - |
| REFERENCES | Johnsen JM, et al. Novel approach to genetic analysis and results in 3000 hemophilia patients enrolled in the My Life, Our Future initiative. Blood Adv. 2017 May 18;1(13):824-834. |
| SAMPLE REPORT | Upon request |
| NEW YORK STATE APPROVED | - |
Test Codes
| ORDER CODE | P3392 |
| CPT CODE | 81479 |
| LOINC CODE | 94234-2 |