DNA Hemophilia A Mutation Screen
| Also Known as (Alias) | HemA Genotyping; F8 Genotyping |
| Method | Polymerase Chain Reaction (PCR) Based |
| Test Information | Patients with severe hemophilia A that are negative for the DNA Factor VIII inversion or patients that have moderate or mild hemophilia can be evaluated for variants by Sanger sequencing of the 26 exons of the F8 gene and the 5’untranslated and 3’ untranslated regions. Through our current screening methods, a variant is found ~96% of the time.
Reference guidelines and variant databases: CDC Hemophilia Mutation Projects (CHAMP) | Hemophilia | CDC If the specific variant cannot be identified, intragenic linkage is often useful to trace the affected allele through the family tree. Linkage studies also help identify the de novo origin of mutations in families with an isolated occurrence (eg: maternal grandparents). Linkage studies may be informative in families who have hemophilia A where no variant is able to be identified in the proband 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 some moderate cases with FVIII levels of ~1%), the DNA Factor VIII Inversion testing will be negative. For these patients, along with the moderate and mild patients, the Hemophilia A Mutation Evaluation will be performed to identify the causative variant. Screening of the F8 gene will be performed by Sanger sequencing. If no causative variant is identified through Sanger sequencing, Multiplex Ligation-dependent Probe Amplification (MLPA) is performed.
Confirmation is performed by sequencing the exon in which the variant is located or by MLPA if necessary. |
| Sample Requirements | EDTA (lavender top) or extracted DNA |
| Requested Volume | 3-10cc EDTA (lavender top) tube or >10 ug extracted DNA at a concentration of >25ng/ul.
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 ambient temperature (or on dry ice) and should arrive in the lab within 48 hours of the blood draw.
Send whole blood samples to: Cultured amniocyte samples shipped at ambient temperature and should arrive in the lab within 48 hours and received Tuesday through Thursday. Send cultured amniocyte samples to: Do not send samples to arrive on weekends or federal holidays or after 1pm on Fridays For additional information, please see Ordering Information-Bleeding Disorders |
| Requisition Form | Request for Testing Eastlake Bleeding Disorders Laboratory |
| Transaction Code | 3250-02 |
| CPT Codes | 81407 |
| Turn around Time (analytic time) | 2-4 weeks. If Multiplex Ligation-dependent Probe Amplification (MLPA) testing is necessary, it may take up to a couple of months. |
| Report/Results | Reports will be faxed or emailed. |
