DNA Hemophilia B Mutation Screen
| Also Known as (Alias) | HemB genotyping; F9 genotyping |
| Method | polymerase chain reaction (PCR) based |
| Test Information | Analysis of the Factor IX gene (Hemophilia B) is performed by direct sequence analysis of exons 1 – 8 and one common recurrent 3′ ut region genotype. The Genomics Testing Laboratory has had a high level of success in locating the mutation within these areas (Weinmann et al, BJ Haematol 100: 58, 1998). A reference for the DNA FIX mutation database can be found at http://www.factorix.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 4 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 | Sequencing is performed for exons 1-8 and the 3′ ut region. 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 OR
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 | 3250-10 |
| CPT Codes | 81405 |
| Turn around Time (analytic time) | 5-10 business days |
| Report/Results | Fax number required to receive report |