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The Curacao criteria, published in 2000, remain the mainstay of HHT clinical diagnosis:
- Recurrent, spontaneous nosebleeds
- Mucocutaneous telangiectases at characteristic sites (fingertips, lips, oral mucosa, tongue)
- Visceral AVMs (gastrointestinal, pulmonary, hepatic, cerebral, or spinal)
- Family history (first-degree affected relative)
Definite HHT = 3 or 4 criteria
Possible HHT = 2 criteria
Unlikely HHT = 0 or 1 criteria
If there is family history but no other criteria for HHT, the condition cannot be excluded. Even in the absence of clinically apparent symptoms, the probability of HHT status in a first-degree relative of an HHT patient is:
- 50% at birth
- 22% at age 16
- 5% at age 40
- 1% at age 60
Such individuals should be considered to have "possible HHT" until proven otherwise.
Genetic testing for endoglin, ALK1/ACVRL1 and Smad4 is available and can confirm the diagnosis in about 80% of cases. The mutation is family-specific; therefore, only the index case needs full genetic testing. Other family members need only be tested for the family-specific gene mutation, which is much less expensive and laborious. In about 20% of patients with HHT, genetic testing does not discover the causative mutation.
Genetic testing is most helpful in the settings of
- A potentially unaffected family member in whom the diagnosis of HHT cannot be excluded clinically.
- A patient with suggestive, but not confirmatory, clinical features of HHT, in whom a positive test would be diagnostic.
Clinical work-up begins with a clinical evaluation at an HHT center of excellence, such as UCLA. Please call or e-mail us to arrange an appointment.