Haemophilia A and Haemophilia B (where the type of haemophilia present in the family is not known)
Haemophilia is a disorder of blood coagulation largely affecting males and results from deficiency of either factor VIII or IX. It is characterised by a prolonged oozing from wounds after injuries, surgery or tooth extractions. Individuals with severe haemophilia who are often diagnosed before the age of 2 years, and may have frequent spontaneous bleeding, whereas those with moderate or mild disease may not receive a diagnosis until later in life.
10-15% of female carriers may be experience bleeding symptoms, especially after major trauma or surgical procedures.
Indications for Testing
Genetic testing to confirm or to help exclude the presence of a mutation associated with haemophilia A or haemophilia B.
Testing the relatives of a previously diagnosed individual reported to have a historic diagnosis of haemophilia, where the type of haemophilia is not known, for clinical management and genetic counselling.
Sequencing of the protein-coding regions of the F8 and F9 genes is expected to be able to detect >90% of disease alleles in relatives of a male patient with moderate and mild haemophilia A and B patients and in those with severe haemophilia B and approximately 50% of mutations associated with severe haemophilia A. The remaining 50% may have intron 1 or intron 22 inversion mutations.
In some individuals, testing for exon deletions/duplications may be appropriate.
Haemophilia B gene review http://www.ncbi.nlm.nih.gov/books/NBK1495/
Goodeve AC. Hemophilia B: Molecular Pathogenesis and Mutation Analysis.
J Thromb Haemost 2015;13:1184-95
Venous blood (2-5ml K-EDTA, not to be frozen prior to or during transport)
Genomic DNA (approximately 5μg)
Specimen containers and referral forms must be labelled with at least two corresponding unique identifiers.
Approximately 8 weeks (40 working days) from receipt of sample. A priority service may be available for urgent referrals at an additional cost, please contact the laboratory for further information.
Referrals must generally be made from the Clinical Genetics services or appropriate clinical specialist. It is assumed that informed consent for genetic testing has been obtained from the patient or their parent/guardian and that the implications of a positive result for other family members have been discussed.
Test options available
(please select from dropdown box at the top of the page or click here)
- F8 gene analysis - NGS of F8 exons
- F9 gene analysis - NGS of F9 1-8 (entire coding region)
- MLPA of F8 and F9 for deletion/duplication analysis
- F8 intron 1 inversion PCR analysis
- F8 intron 22 inversion PCR analysis
- F8 intron 1 & intron 22 inversion PCR analysis
Haemophilia A/Factor VIII deficiency Diagnostic Test