Molecular mechanisms and clinical manifestations of hereditary hemorrhagic telangiectasia

Hereditary Hemorrhagic Telangiectasia (HHT) is charactered by telangiectasia and arteriovenous malformations (AVMs). Recurrent visceral and mucocutaneous bleeding is frequently reported among HHT patients, while data on the prevalence of thrombosis remains limited. This study aims to describe the clinical manifestations and molecular biological characteristics of HHT patients.

We conducted a retrospective study at Ruijin Hospital, affiliated with Shanghai Jiao Tong University School of Medicine. A total of 24 HHT patients, observed between January 2019 and December 2023, were included. We recorded the biological, clinical, and therapeutic events, with particular attention to bleeding and thrombotic events. Gene mutation analysis and blood constituent measurements were performed.

The prevalence of bleeding among all HHT patients was 100 %, while thrombotic events were noted in 41.70 % of cases. Hepatic arteriovenous malformations (HAVMs) were identified in six patients, pulmonary arteriovenous malformations (PAVMs) in five patients, and cerebral arteriovenous malformations (CAVMs) in one patient. For patients with thrombosis, the discontinuation rates were 23.08 % for antiplatelet therapy and 33.33 % for anticoagulant therapy due to the increased risk of bleeding. Genetic mutations related to HHT were present in 16 patients, with ACVRL1 (activin A receptor-like type 1) mutations being the most frequent at 41.67 %, followed by ENG (endoglin) mutations at 20.83 %, and GDF2 (growth differentiation factor 2) mutations at 4.17 %. The incidence of PAVMs was 75.00 % in HHT1 patients with ENG mutations and 20 % in HHT2 patients with ACVRL1 mutations, while HAVMs occurred in 0 % and 40.00 % of these groups, respectively. Patients were divided into non-AVMs and AVMs groups. Compared to normal controls, von Willebrand factor (vWF) activity was significantly increased in all HHT patients (149.10 % vs. 90.65 %, P < 0.001). In the non-AVMs group, the median level of stromal cell-derived factor-1 (SDF-1) was significantly elevated (124.31 pg/mL vs. 2413.57 pg/mL, P < 0.05), while vWF antigen levels were markedly higher in the AVMs group (165.30 % vs. 130.60 %, P = 0.021). Further grouping of HHT patients based on bleeding and thrombosis phenotypes revealed that those with thrombosis had significantly higher median percentages of schistocytes (3.50 % vs. 0 %, P = 0.002), ferritin concentrations (318.50 μg/L vs. 115.50 μg/L, P = 0.001), and lactate dehydrogenase (LDH) levels (437 U/L vs. 105 U/L, P < 0.001). There were no significant differences in the activity of vWF, protein C (PC), protein S (PS), and factor VIII (FVIII) between the two groups.

This study highlighted the complex relationship between arteriovenous malformations and genetic mutations in HHT patients. A comprehensive assessment of bleeding and thrombosis risks should be conducted for each HHT patient, additionally, further clinical studies are needed to explore the risk factors for thrombosis and anticoagulant-related bleeding in HHT.