Appropriate 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: Mutations in endoglin (ENG), activin A receptor type II-like 1 (ACVRL1 or ALK1), SMAD4 or other unidentified gene(s).
Clinical Sensitivity: Approximately 85 percent
Methodology: Bidirectional sequencing of ENG and ACVRL1 -all exons and exon/intron boundaries, including the 5' untranslated region of ENG; Multiplex Ligation-dependent Probe Analysis (MLPA) to detect large ENG and ACVRL1 gene deletion/duplication; oligonucleotide probes cover all ENG and ACVRL1 coding exons.
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.
|Component Test Code*||Component Chart Name||LOINC|
|2009010||HHT Seq/DelDup Interpretation|
|2009011||HHT Seq/DelDup Specimen|