Acceptable test when clinical/family history is classic for HHT.
- Patient Preparation
- Lavender (EDTA), pink (K2EDTA), or yellow (ACD Solution A or B).
- Specimen Preparation
- Transport 3 mL whole blood. (Min: 2 mL)
- Storage/Transport Temperature
- Unacceptable Conditions
- Ambient: 72 hours; Refrigerated: 1 week; Frozen: Unacceptable
Characteristics: Recurrent nosebleeds, telangiectases (mouth, face, hands, GI tract), and arteriovenous malformations (lung, brain, liver, spine).
Inheritance: Autosomal dominant.
Penetrance: Approaches 100 percent by age 40.
Cause: Pathogenic mutations in ENG, ACVRL1/ALK1, SMAD4, BMP9/GDF2 or other unidentified gene(s).
Genes Tested:ENG and ACVRL1
Clinical Sensitivity: Approximately 85 percent
Methodology: Bidirectional sequencing and multiplex ligation-dependent probe amplification (MLPA) of the entire coding regions and intron-exon boundaries of ENG and ACVRL1, as well as the 5' untranslated region of ENG.
Analytic Sensitivity: 99 percent for sequencing and 90 percent for MLPA.
Analytic Specificity: 99 percent for sequencing and 98 percent for MLPA.
Limitations: Diagnostic errors can occur due to rare sequence variations. The breakpoints of large deletions/duplication cannot be determined. Regulatory region, intronic mutations, and mutations in genes other than ENG and ACVRL1 will not be detected.
Counseling and informed consent are recommended for genetic testing. Consent forms are available online.
|Component Test Code*||Component Chart Name||LOINC|
|0051350||HHT, Sequencing and Deletion/Duplication|
|2001355||HHT, Seq-Del/Dup - Specimen|
- Activin A Receptor, Type II-Like I
- ACVRL1 Gene; ALK1 Gene
- Arteriovenous Malformations
- AVM genetic testing
- HHT molecular testing