The clinical and genetic features of hereditary haemorrhagic telangiectasia (HHT) in central South Africa-three novel pathogenic variants.

Hereditary haemorrhagic telangiectasia (HHT) is supposedly rare in Africa, with only three pathogenic variants documented to date. We describe the clinical and genetic features of HHT patients in central South Africa, who fulfilled the Curaçao criteria. Sixteen patients (median age 38.5 years, range 12-65 years), from six families were included. Fifteen patients were of African descent and one was of Afrikaner descent. The mean epistaxis severity score was 3.18, and the median haemoglobin was 9.5 g/dL (range 3.5-13.5 g/dL). On transthoracic contrast echocardiography 69% had a shunt grade ≥ 1, but only 20% had pulmonary arteriovenous malformations (AVMs) on computed tomography of the chest. Hepatic AVMs were found in 13% of patients, while 13% had brain vascular malformations. Four patients were HIV positive, of whom two had worsening epistaxis while they had opportunistic infections and poor HIV control. We identified six pathogenic variants (four in ENG and two in ACVRL1) in the six probands, three of which had been described previously. Three variants have apparently not been reported previously: ENG c.[1336_1337dup];[ =] p.[(Asp446fs)];[( =)], ENG c.[ 690?_816+?del] p.[(?)], and ACVRL1 c.[268_274delins57];[ =] p.[(Cys90fs)];[( =)]. We confirmed the diagnosis of HHT in sixteen patients and identified pathogenic variants in ENG or ACVRL1 in all six probands in central South Africa, where HHT has been underreported. We describe three pathogenic variants: two of ENG and one of ACVRL1. We will be able to implement pre-symptomatic screening of patients in our area, and improve their management.