Hereditary hemorrhagic telangiectasia is characterized by the presence of arteriovenous malformations (AVMs), spontaneous and recurrent nosebleeds (epistaxis), and telangiectases. The age of onset and severity of symptoms vary widely and recurrent epistaxis is the most common first symptom beginning in early adolescence.

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Test Code 8672
Turnaround Time (TAT) 14-21 days
Number of Genes 6

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We offer family variant testing at no additional cost

We offer family variant testing for all blood relatives of patients who undergo full single gene sequencing, multigene panel testing or exome sequencing at Ambry Genetics and are found to have a pathogenic or likely pathogenic variant. Testing must be completed within 90 days of the original report date. Whenever possible, more closely related relatives should be tested before more distant relatives. If you or a family member are interested in learning more about our family testing program or when family testing may be clinically indicated, please contact us or your provider for additional information. Note that Ambry can only provide such family testing services to patients receiving medical care in the U.S or US territories.

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Why Is This Important?

Knowing if your patient has a hereditary hemorrhagic telangiectasia can help you determine future risks and guide your medical management recommendations. Key benefits include:

  1. If you have been clinically diagnosed with possible HHT according to the Curacao diagnostic criteria, genetic testing may be done to establish or confirm a diagnosis.
  2. If you have been clinically diagnosed with definite HHT, genetic testing may be done to identify the affected gene in order to accurately test other family members.
  3. If you have a direct relative who has been genetically diagnosed, genetic testing would be done to test for the presence or absence of the mutation that was identified in your family member. The presence of the family HHT-causing mutation would prove HHT, while its absence would rule it out

When To Consider Testing

  • Recurrent and spontaneous nosebleeds (epistaxis), which may be mild to severe.
  • Multiple telangiectases on the skin of the hands, lips or face, or inside of the nose or mouth. Telangiectases are small red spots that disappear when pushed on.
  • Arteriovenous malformations (AVMs) or telangiectases in one or more of the internal organs, including the lungs, brain, liver, intestines, stomach, and spinal cord.
  • A family history of HHT (i.e. first-degree relative such as brother, sister, parent or child who meets these same criteria for definite HHT or has been genetically diagnosed).

Mutation Detection Rate

The HHTNext test is designed and validated to be capable of detecting >99% of described mutations in the genes represented on the tests (analytical sensitivity). The clinical sensitivity of the HHTNext test may vary widely according to the specific clinical and family history.

Test Description

HHTNext is a comprehensive analysis of 6 genes associated with hereditary hemorrhagic telangiectasia. Genomic deoxyribonucleic acid (gDNA) is isolated from the patient’s specimen using standardized methodology and quantified. Sequence enrichment of the targeted coding exons and adjacent intronic nucleotides is carried out by a bait-capture methodology using long biotinylated oligonucleotide probes, and is followed by polymerase chain reaction (PCR) and Next-Generation sequencing (NGS). Additional Sanger sequencing is performed for any regions missing or with insufficient read depth coverage for reliable heterozygous variant detection. Potentially homozygous variants, variants in regions complicated by pseudogene interference, and variant calls not satisfying depth of coverage and variant allele frequency quality thresholds are verified by Sanger sequencing. This assay targets all coding domains, and well into the flanking 5’ and 3’ ends of all the introns and untranslated regions. Gross deletion/duplication analysis is performed for all genes using a custom pipeline based on read-depth from NGS data followed by a confirmatory orthogonal method, as needed. Exon-level resolution may not be achieved for every gene.


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