What are the implications of HHT for family members, and how should I approach genetic counseling in these cases?

Implications of hereditary hemorrhagic telangiectasia (HHT) for family members: HHT is an autosomal dominant genetic disorder, meaning that first-degree relatives of an affected individual have a 50% chance of inheriting the pathogenic variant and thus being at risk of developing the condition. Family members may be asymptomatic carriers or may develop symptoms such as telangiectasia and arteriovenous malformations, which can lead to serious complications. Early identification of at-risk relatives is important for surveillance and management to prevent complications.

Approach to genetic counseling in HHT cases: Genetic counseling should be offered to affected individuals and their family members to discuss the inheritance pattern, implications of genetic testing, and the potential outcomes for relatives. Counseling should include pre-test discussions about the benefits, limitations, and possible results of genetic testing, including the possibility of identifying a pathogenic variant or a variant of uncertain significance. Testing should ideally begin with an affected family member to identify the familial mutation. Cascade testing can then be offered to at-risk relatives. Counseling should be provided by healthcare professionals with appropriate training in genetics, and referrals to specialist genetic services should be made when necessary. Family members should be informed about the availability of surveillance and management options if they test positive for the familial mutation.