Novel mutations in ENG and ACVRL1 identified in a series of 200 individuals undergoing clinical genetic testing for hereditary hemorrhagic telangiectasia (HHT): correlation of genotype with phenotype

Genotype-phenotype correlations in hereditary hemorrhagic telangiectasia: data from the French-Italian HHT network

PURPOSE

Hereditary hemorrhagic telangiectasia is an autosomal dominant disorder characterized by arteriovenous malformations (AVM), mostly cutaneous and mucous (telangiectases), but also involving the lungs (PAVM), liver (HAVM) and brain (CAVM). We studied the relationship between the phenotype and genotype in patients with a proven mutation in either ENG (HHT1) or ACVRL1 (HHT2).

METHODS

Clinical features and their age of onset were compared between HHT1 and HHT2. The type of mutation was also analyzed. Clinical manifestations were distinguished from lesions found by screening.

RESULTS

Ninety-three HHT1 patients and 250 HHT2 patients were included. Epistaxis occurred later in HHT2, with incomplete penetrance (P<0.0001). Symptomatic PAVMs were more frequent in HHT1 (34.4 vs. 5.2%, P<0.001), as were cerebral abscesses (7.5 vs. 0.8%, P=0.002). Gastrointestinal bleeding occurred more frequently in HHT2 (16.4 vs. 6.5%, P=0.017). Symptomatic hepatic involvement was only seen in HHT2 patients. PAVMs were more frequently detected in asymptomatic HHT1 patients (54 vs. 12.8%, P<0.0001). PAVMs and HAVMs were often family clustered in HHT1 and HHT2, respectively. Truncating mutations were associated with a higher frequency of epistaxis and telangiectasis, in HHT2.

CONCLUSION

This study shows major differences between HHT1 and HHT2 phenotypes, which should be taken into account for future clinical studies.

Pulmonary arteriovenous malformations in hereditary hemorrhagic telangiectasia: a series of 126 patients

Hereditary hemorrhagic telangiectasia (HHT) is a genetic disorder characterized by epistaxis, telangiectasia, and visceral vascular manifestations. Infectious and ischemic central nervous system (CNS) manifestations due to embolism through pulmonary arteriovenous malformations (PAVMs) represent the main causes of morbidity. To improve the phenotypic characterization of HHT with PAVM, we conducted a retrospective multicenter study of patients with HHT and at least 1 PAVM detected by chest computed tomography (CT) and/or pulmonary angiography, with particular attention to CNS and infectious manifestations. The study included 126 patients (47 men, 79 women), with a mean age of 43.1 +/- 17.4 years; 45 patients had a mutation of the ENG gene and 16 had a mutation of ACVRL1. PAVMs were diagnosed as a result of systematic screening procedures (29%), incidental imaging findings (15%), dyspnea (22%), or CNS symptoms (13%). The PAVMs were diagnosed at a mean age of 43 +/- 17 years, with a linear distribution of diagnosis between 20 and 75 years. Dyspnea on exertion was present in 56% of patients. Four patients had a hemothorax, including 1 during pregnancy. Fifty-three CNS events directly related to HHT (excluding migraine) were observed in 35% of patients: cerebral abscess (19.0%), ischemic cerebral stroke (9.5%), transient cerebral ischemic attack (6.3%), and cerebral hemorrhage (2.4%). The median age of onset was 33 years for cerebral abscesses (range, 11-66 yr), and 53.5 years for ischemic cerebral events (range, 2-72 yr). Migraine was reported in 16% of patients. The diagnoses of PAVM and HHT were made at the time of the cerebral abscess in 13 cases (54%). Forty-three percent of patients were hypoxemic at rest. Contrast echocardiography showed intrapulmonary right-to-left shunting in 87% of tested patients. PAVMs were seen on chest radiograph in 54% of patients, and on the CT scan in all patients. One hundred five patients (83%) underwent treatment of the PAVM, by percutaneous embolization (71%) and/or by surgical resection (23%). A high frequency of CNS and infectious complications was observed in this large series of patients with HHT-related PAVM. Physicians may not be sufficiently aware of the clinical manifestations of this orphan disorder. Patients diagnosed with HHT should be informed by physicians and patient associations of the risk of PAVM-related complications, and systematic screening for PAVM should be proposed, regardless of a patient's symptoms, familial history, or genetic considerations.