DNA Hemophilia A Mutation Screen
| Also Known as (Alias) | HemA genotyping; F8 genotyping |
| Method | polymerase chain reaction (PCR) based |
| Test Information | Severe patients that are negative for the DNA Factor VIII inversion or patients that have moderate or mild hemophilia can be evaluated for mutations. Through our current screening methods, a mutation is found ~90-95% of the time. A reference for the DNA FVIII mutation database can be found at, http://www.factorviii-db.org/(LINK) , and http://www.cdc.gov/ncbddd/hemophilia/champs.html. (LINK)
If the specific mutation cannot be identified, intragenic linkage is often useful to trace the affected allele through the family tree by following 5 polymorphic sites. Linkage studies also help identify the de novo origin of mutations in families with an isolated occurrence (eg: maternal grandparents). Intragenic linkage may be useful in 80-90% of families where key family members (patient and both parents of potential carrier) are available |
| Additional Test Information | For approximately half of the severe hemophilia A patients (and moderate cases with FVIII levels of ~1%), the DNA Factor VIII Inversion (LINK) will be negative. For these patients, along with the moderate and mild patients, the Hemophilia A Mutation Evaluation will be performed to identify the mutation. A MDE (mutation detection enhancement) screen will be performed initially and if needed, will be followed by a sequence screen. Once identified, the genotype will be tested by confirmation analysis.
Confirmation is performed one of two ways. If the mutation creates/removes a restriction enzyme digestion site, the testing will be performed by RFLP. If a restriction enzyme digestion site is not present, testing will be done by sequencing the exon in which the mutation is located |
| Sample Requirements | EDTA (lavender top) |
| Requested Volume | 5-10cc EDTA (lavender top) tube
Analysis of amniocytes can be performed on cultured amniocytes. Two T-25 flasks of cells cultured to confluency will be accepted. Bloodworks Northwest does not have facilities to culture amniocytes. Bloodworks Northwest does not have facilities to culture amniocytes. |
| Shipping Information | Whole blood shipped at 4oC or ambient temperature is acceptable and should arrive in the lab within 48 hours.
Send samples to: |
| Requisition Form | Request for Testing Hemostasis Reference Laboratory |
| Transaction Code | 3250-02 |
| CPT Codes | 81407 |
| Turn around Time (analytic time) | 2-4 weeks |
| Report/Results | Fax number required to receive report |