Q: Why should a family member of an HHT patient be screened even if no symptoms have appeared?
Dr. Jeffrey Pollak, Medical Director of Yale University HHT Center: People with a family history of HHT, even those without symptoms, are potentially at-risk for having the condition and associated internal AVMs. Anyone with a parent, sibling or child with HHT is considered at-risk. Features leading to a suspicion of HHT, like nosebleeds and telangiectasia, often do not appear until adolescence or later, and sometimes never appear. Approximately 10% of adults with HHT do not have nosebleeds and skin telangiectasia can be subtle, so the absence of these signs does not exclude the condition. Lung and brain AVMs often don't cause symptoms, but if it is of a significant size, it can increase the risk for stroke, brain abscess and hemorrhage. Indeed, these serious complications can be the first evidence of the presence of AVMs, for which preventive therapy is available.
The most accurate way to determine who in a family has HHT is through genetic testing. A family member with definite HHT, based on clinical findings, is first tested to determine the family’s mutation, which is possible in 85% to 90% of families with HHT. Testing for this known mutation can then be done on at-risk family members with no or minimal symptoms. Only those with the family’s mutation would need HHT evaluation and AVM screening. Since the potentially life-threatening complications associated with HHT are preventable with appropriate treatment and follow-up, we recommend genetic testing and/or screening at-risk family members, even in the absence of symptoms.