This is a genotype with recommended actions if clinically confirmed. In brief:
- Hereditary hemorrhagic telangiectasia (HHT) is characterized by the presence of multiple arteriovenous malformations (AVMs) that lack intervening capillaries and result in direct connections between arteries and veins. This may result in bleeding (such as nosebleeds).
- Mutations in the ACVRL1, ENG, GDF2 and SMAD4 genes may lead to HHT.
- Undergo an annual evaluation by a health care provider familiar with HHT, including interval history for epistaxis or other bleeding, shortness of breath or decreased exercise tolerance, and headache or other neurologic symptoms.
- For those prone to HHT-related nosebleeds: Humidify your nose or use ointments to reduce bleeding; avoid vigorous nose blowing, lifting of heavy objects, straining during bowel movements, and picking your nose; avoid scuba diving unless contrast echocardiography performed within the last five years was negative for a right to left shunt; be aware that the use of anticoagulation/antiplatelet drugs can increase bleeding.
- Get screened for cerebral and pulmonary arteriovenous malformations (PAVMs) using transthoracic contrast echocardiography (TTCE) every 5-10 years and within 5 years preceding a planned pregnancy.
- Those over 35 should have annual measurements of hemoglobin or hematocrit levels due to the increased risk of GI bleeding with age. Oral and/or intravenous iron supplementation is recommended as first-line therapy for mild anemia and chronic bleeding secondary to HHT-related telangiectasia.
- Consider diagnostic testing for all at risk family members and relatives, including asymptomatic children.
The full ClinGen Actionability report about hereditary hemorrhagic telangiectasia (HHT) can be found here.
Genetic counseling may be available to you through your health-care network. In the US, genetic counselors may be found via this webpage of the National Society of Genetic Counselors.