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/, and http://www.cdc.gov/ncbddd/medical-services/wa-center-for-bleeding-disorders/champs.html.
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 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.
|Shipping Information||Whole blood shipped at 4oC or ambient temperature is acceptable and should arrive in the lab within 48 hours.
Send samples to:
For additional information, please see Ordering Information-Bleeding Disorders
|Requisition Form||Request for Testing Hemostasis Reference Laboratory|
|Turn around Time (analytic time)||2-4 weeks|
|Report/Results||Fax number required to receive report|