Clinical and Analytical Sensitivities in Hereditary Hemorrhagic Telangiectasia Testing and a Report of de Novo Mutations

Abstract

Hereditary hemorrhagic telangiectasia is a vascular dysplasia with variable onset and expression. Through identification of a mutation in a proband, mutation testing can be offered to family members. Mutation carriers can receive medical surveillance and treatment before potentially fatal complications arise. In this study, we assessed the significance of clinical evaluations as part of hereditary hemorrhagic telangiectasia diagnostic testing to determine the clinical sensitivity of molecular testing and to report novel mutations. Based on reported clinical symptoms, we classified 142 consecutive cases as affected, suspected, or unlikely affected. We performed temperature gradient capillary electrophoresis and full gene sequencing of both ACVRL1 and ENG genes. We then compared the mutation detection rates between these groups, categorizing sequence variants as mutations, variants of uncertain significance (VUS), or known polymorphisms. Our mutation and VUS detection rate in affected individuals was 74% and 16% in the suspected/unlikely affected group. Sixty-one percent of the mutations and all VUS were novel. The mutation detection rate for temperature gradient capillary electrophoresis was 97%. Our results suggest that a careful clinical evaluation increases the mutation detection rate. We have confirmed the occurrence of de novo mutations in three patients. Our results also show that temperature gradient capillary electrophoresis is an efficient mutation screening method. Hereditary hemorrhagic telangiectasia (HHT) is characterized phenotypically by telangiectases and arteriovenous malformations. These lesions result in hemorrhage, particularly in the nose, gastrointestinal tract, and brain, and complications related to shunting, primarily in the lungs and liver. Complications from this disorder include intracranial hemorrhage secondary to cerebral arteriovenous malformations and embolic stroke and brain abscess secondary to pulmonary arteriovenous malformations. The frequency of HHT is reported to be ϳ1 in 10,000, but it is thought to be underdiagnosed. 1Two genes, endoglin (ENG) and activin receptor-like kinase 1 (ACVRL1), have been reported to cause HHT in an autosomal dominant manner if mutated.2 Molecular diagnosis allows for diagnostic confirmation in symptomatic individuals and significantly improves care for individuals at risk for HHT after identification of a causative mutation. Because the initial clinical presentation of the disorder can be a catastrophic pulmonary or central nervous system event, 3-5 presymptomatic diagnosis for relatives of individuals with HHT offers an opportunity to prevent serious or lethal complications. Individuals shown to be unaffected can be spared unnecessary and costly medical screening. Developing simple and reliable diagnostic approaches has been difficult because of the lack of common mutations.2 Thus, sensitive mutation scanning approaches followed by targeted sequencing might be useful in the clinical setting.To detect mutations many scanning techniques have been ...

Clinical features of pulmonary arterial hypertension in young people with an ALK1 mutation and hereditary haemorrhagic telangiectasia

“…Sequence assembly and analysis was performed using Phred, PHRAP, parcel genome assembler ARACHNE, and Consed with proprietary LIMS-integrated finishing software. Clinical mutation analysis for ACVRL1 / ALK1 and ENG was performed using previously published methods, by one of two clinical laboratories, ARUP21 (also see ARUP technical bulletin at http://www.aruplab.com/guides/ug/tests/0051348.jsp) or HHT Solutions 11…”

Novel ACLV1 Mutation Identified in Late Onset Hereditary Hemorrhagic Telangiectasia

“…The Smad dimer then enters the nucleus where it acts as a transcription factor, regulating the transcription of angiogenesis genes such as VEGF. Reduced presence of endoglin, a coreceptor for ALK family of receptors, has been shown to decrease the activity of the ALK1 pathway, as well as the ALK5 pathway that counterbalances ALK1 activity by promoting cell c.24A > T Missense p.Lys8Ans [16] c.31_50del20 Deletion p.Leu11Glyfs*20 [17] c.37delC Deletion p.Leu13Cysfs*2 [18] c.50dupT Duplication p.Leu17Phefs*21 [19] c.50_53delTGGT Deletion p.Leu*17 [20] c.61 + 1G > A Missense p.? [14] c.61 + 10G > A Splice Site p.?…”

“…[31] c.773-2A > C Splice Site p.? [19] c.778A > C Missense p.Ile260Leu [24] c.793A > C Missense p.Thr265Pro [37] c.811_823del13bp Deletion p.Thr271Serfs*26 [35] c.818T > C Missense p.Leu273Pro [48] c.821_824dupGGCT Duplication p.Ile276Alafs*117 [40] c.822G > A Missense p.Trp274* [45] c.827T > C Missense p.Ile276Thr [48] c.835_837dupTAC Duplication p.Tyr279dup [14] c.838C > G Missense p.His280Asp [25] c.839A > G Missense p.His280Arg [45] c.842delA Deletion p.Glu281Glyfs*20 [26] c.851C > T Missense p.Ser284Phe [48] c.853dupC Duplication p.Leu285Profs*107 [20] c.853C > T Missense p.Leu285Phe [31] c.854T > C Missense p.Leu285Pro [58] c.858C > G Missense p.Tyr286* [25] c.858C > A Missense p.Tyr286* [35] c.863_909del47 Deletion p.Phe288Cysfs*88 [14] c.864dupT Duplication p.Leu289Serfs*103 [38] Continued c.866T > C Missense p.Leu289Pro [24] c.870delG Deletion p.Arg219Aspfs*10 [14] c.874delC Deletion p.Gln292Argfs*9 [30] c.874C > T Missense p.Gln292* [19] c.875A > C Missense p.Gln292Pro [26] c.881T > G Missense p.Leu294Arg [45] c.905T > G Missense p.Leu302Arg [26] c.913T > C Missense p.Ser305Pro [48] c.913delT Deletion p.Ser305Profs*49 [59] c.914C > T Missense p.Ser305Phe [17] c.916G > C Missense p.Ala306Pro [31] c.917C > A Missense p.Ala306Glu [30] c.921_927dupATGCGGC Duplication p.Leu310Metfs*84 [47] c.924C > A Missense p.Cys308* [38] c.925G > T Missense p.Gly309Cys ...…”

Molecular diagnosis utility of multiplex ligation-dependent probe amplification

“…In a complex gene, large exons and lack of common mutations (hot spots) make molecular diagnosis difficult and, if tested by sequencing alone, decrease the clinical detection rate (excluding X-linked DMD) [16][17][18] . Therefore, a reliable and robust molecular assay is needed to detect deletions or duplications, especially at an exonic level.…”