Hereditary Hemorrhagic Telangiectasia (HHT)

Epidemiology and Etiology:

· Autosomal dominant inheritance

· ENG (endoglin) (HHT1)

· Mutation

· ACVRL1 (activin receptor) (HHT2)

· Mutation

· These 2 genes detect 60-80% of cases

· Overlap JPS/HHT (SMAD4)

· Juvenile polyposis syndrome with HHT

Common sites:

· Multiple AVMs

· Mucocutaneous

· Lung

· Brain

· Spinal cord

· Liver

· GI

Gross features:

· small blanchable red spots on mucosal and cutaneous surfaces

· lips

· oral cavity

· fingers

· nose

Histologic features:

·

Immunophenotype:

Marker:

Sensitivity:

Specificity:

Molecular features:

· Gene sequencing (ENG and ACVRL1) (60-80%)

· SB or MLPA for deletions (~10%)

Other features:

· Small AVMs close to skin surface or mucous membranes often rupture and bleed after slight trauma

· Recurring spontaneous nose bleeds

· Beginning at ~12 y

· GI bleeds

· Beginning > 40 y

· Large AVMs in brain, lungs, or GI tract may cause sudden and catastrophic complications

· Bleeding

· shunting

References:

· Genetests.org