Spectrum of Novel Hereditary Hemorrhagic Telangiectasia Variants in an Austrian Patient Cohort.

Objectives. Hereditary hemorrhagic telangiectasia (HHT) is a rare autosomal dominant genetic disorder characterized by pathogenic blood vessel development and maintenance. HHT type 1 (HHT1) and type 2 (HHT2) arc caused by variants in endoglin (ENG) and activin receptor-like kinase-1. (ACVRL1), respectively. The aim of this study was to identify the spectrum of pathogenic variants in ENG and ACVRL1 in Austrian HHT families. Methods. In this prospective study, eight Austrian HHT families were screened for variants in ENG and ACVRL1 by polymerase chain reaction amplification and sequencing of DNA isolated from peripheral blood. Results. Heterozygous variants were identified in all families under study. HHT1 was caused by a novel c.816+1G>A splice donor variant, a novel c.1479C> A nonsense (p.Cys493X) variant and a published c.1306C>T nonsense (p.Gln436X) variant in ENG. Variants found in ACVRL1 were novel c.200G>C (p.Arg67Pro) and known c.772G >A (p.Gly258Ser) missense variants in highly conserved residues, a known heterozygous c.100dupT frameshift (p.Cys34Leufs*4) and the known c.1204G> A missense (p.Gly402Ser) and c.1435C>T nonsense (p.Arg479X) variants as causes of HHT2. Conclusion. Novel and published variants in ENG (37.5%) and ACVRL1 (62.5%) were exclusively identified as the cause of HHT in an Austrian patient cohort. Identification of novel causative genetics variants should facilitate the development of tailored therapeutical applications in the future treatment of autosomal dominant HHT.