Mutation detectionin the endoglin gene in a family with hereditary haemorrhagic telangiectasia

[摘要] Introduction: Hereditary haemorrhagic telangiectasia (HHT) is a rare autosomaldominant bleeding disorder. It is characterised by the presence of mucocutaneoustelangiectases, visceral arteriovenous malformations and epistaxis. The phenotype isdiagnosed according to the Curaçao criteria. At a molecular level, HHT has beenlinked to the Endoglin, Activin kinase 1 (ALK1) and SMAD4 genes in numerousstudies. The majority of studies are centred on European and American populationgroups. There are few publications of HHT on people of African descent, none ofwhich are family based studies. To our knowledge, this is the first study presentingmRNA expression sequence data of the Endoglin (ENG) gene in a population ofAfrican descent. The aim of the study is to detect splice site and exon regionmutations present in the ENG gene of the family members affected with HHT.Methodology: RNA was isolated from blood, stabilised in RNAlater and stored at -20ºC using the Ribopure blood kit and TRizol® methods. The RNA was converted tocDNA that served as a template molecule for sequence mutation detection. In total11 primer pairs were designed and used to amplify 15 exon regions of the endoglingene. Sanger sequencing was employed to determine ENG mutations. Results:Four mutations were identified, two in exon 1, namely c.-324A>G and c.-207G>Aand two missense mutations c.640G>A and c.1510G>A located in exon 5 and exon11 were identified, respectively. The exon 1 mutation c.-324A>G is a populationvariant. The c.-207G>A exon 1 mutation was concluded to have no effect on theresulting amino acid and only one HHT individual harboured this mutation. Themissense mutations c.640G>A and c.1510G>A were previously described inparticipants with and without HHT in literature, resulting in conflicting interpretationsregarding HHT causality. Results from this study indicate that the latter mutationsoccurred in two different individuals that have been diagnosed with HHT.Conclusion: The identified mutations were present in individuals who were formerlydiagnosed with HHT but none of them can be proven to be pathogenic, since it wasnot present in all the HHT affected family members. Future studies should focus onthe mutation detection of other HHT associated genes such as SMAD4, ALK1,BMP9 and RASA1 genes in this family to decipher HHT pathogenesis in a familyfrom African descent.

[发布机构] University of the Free State