遗传性出血性毛细血管扩张症基因突变分析

目的 分析遗传性出血性毛细血管扩张症(hereditary hemorrhagic telangiectasia,HHT)家系ENG、ACVEL1和SMAD4基因突变.方法 收集4个HHT家系临床资料并分析其临床特点,应用直接测序和多重连接探针扩增技术对11例临床确诊及可疑患者的ENG、ACVRL1和SMAD4基因进行突变分析,将结果与HHT基因突变数据库进行对比.结果 家系2先证者及2个妹妹的ENG基因发生了第2外显子c.207G＞A(p.L69L)同义突变、第8外显子c.1004A＞T(p.Q335L)错义突变、ACVRL1基因第7外显子c.817C＞T(L273L)同义突变;家系3先证者及其母亲和弟的ENG基因发生了第8外显子c.1004A＞T(p.Q335L)突变;也检测到家系4先证者及其兄的ENG基因第8外显子c.1004A＞T(p.Q335L)突变.家系1先证者及其他HHT患者,未检测到基因突变.其中ENG基因第8外显子c.1004A＞ T(p.335Q＞L)为新突变,在200名正常对照中也未检测到该突变.结论 HHT具有遗传异质性,ENG基因第8外显子c.1004A＞T(p.Q335L)为HHT新的致病突变.     

Cost savings through molecular diagnosis for hereditary hemorrhagic telangiectasia

PurposeHereditary hemorrhagic telangiectasia (HHT) is an autosomal dominant disorder of vascular development resulting in direct connections between the arterial and venous systems, bypassing capillaries. Symptoms and signs can appear throughout life and marked intrafamilial variability confounds diagnosis based purely on clinical criteria. We set out to determine the impact of genetic testing on the cost of screening for HHT in at-risk relatives.MethodsWe performed economic modeling of idealized pedigrees following two scenarios: repeated clinical screening until an HHT diagnosis could be either affirmed or excluded, and mutation testing in the proband, followed by genetic testing of at-risk relatives and clinical monitoring of only those relatives who test positive for the familial mutation.ResultsBased on actual reimbursement data from our region’s largest health insurer, the molecular diagnostic model saved over $22,000 for a family with four relatives at risk for the initial diagnostic work-up. For a cohort of 100 probands, the total savings for the molecular diagnostic model over a reasonable period of follow-up was greater than $9 million.ConclusionIn this idealized setting in which all probands and at-risk relatives accepted molecular testing, the economic advantages of genetic screening over repeated clinical screening are substantial.Genet Med 2012:14(6):604–610     

Tissue‐specific mosaicism in hereditary hemorrhagic telangiectasia: Implications for genetic testing in families

Mosaicism in hemorrhagic telangiectasia (HHT) has been previously identified when testing blood samples of HHT patients. We report the first detection of mosaicism not involving blood of a family proband, and discuss implications for genetic testing algorithms in HHT families. Sanger sequencing and large deletion/duplication analysis in a patient with HHT identified no pathogenic variant in ENG, ACVRL1, or SMAD4. Exome sequencing was then performed on this proband, as well as her affected adult child. A pathogenic ENG variant was detected in the proband's affected child, but not in DNA extracted from peripheral blood of the affected parent/proband. Additional tissue samples (saliva and hair bulbs) were obtained from the proband. The variant was not detected in saliva, but was detected in the hair bulb sample (at 33%). This is the first report of an HHT patient with mosaicism in whom the disease‐causing mutation was not detected in blood. The molecular findings in this family suggest that the possibility of mosaicism not present or detectable in blood should be considered if a proband with HHT tests “negative” for a mutation in known genes. This occurrence is particularly suspect for families in which the proband does not have a clearly affected parent. This mechanism may explain some patients with classic HHT in whom a pathogenic variant has not been identified in one of the known HHT genes.     

Health screening behaviors among adults with hereditary hemorrhagic telangiectasia in North America

PurposeThis study aimed to identify factors that influence screening behaviors of adults with hereditary hemorrhagic telangiectasia (HHT).MethodsParticipants with a self-reported diagnosis of HHT were recruited from the HHT Foundation International, Inc.; the “HHT Awareness” Facebook group; and six HHT clinics. A cross-sectional mixed methods survey was administered to investigate the relationships among the Health Belief model constructs, the domains of illness representations, and HHT-specific screening behaviors consistent with recommended guidelines.ResultsA total of 320 participants reported rates of cerebral arteriovenous malformation (AVM) screenings, pulmonary AVM screenings, and HHT annual checkups that were 82.0, 67.1, and 56.5%, respectively. Logistical regression analysis showed that perceived barriers (β = −0.114, P < 0.001), perceived susceptibility (β = 0.117, P < 0.05), treatment control (β = 0.078, P < 0.05), and emotional representations (β = 0.067, P < 0.05) were significant predictors of HHT screening. Open-ended responses revealed perceived barriers to screening, including a lack of health-care providers (HCPs) familiar with and/or knowledgeable about HHT.ConclusionOur results reveal suboptimal screening rates among adults with HHT and identify several factors influencing these behaviors. We suggest that there is a need for increased provider education regarding HHT as well as approaches that providers can use to improve screening adherence.Genet Med advance online publication 13 October 2016     

Hepatolithiasis in hereditary hemorrhagic telangiectasia

Hereditary hemorrhagic telangiectasia is a rare, hereditary fibrovascular dysplasia. We report a case associated with hepatolithiasis. Hepatolithiasis, relatively common in East Asia, is rare in the West. The association of the two conditions has not been previously reported. In this case, vascular malformations in the liver gave rise to arteriovenous and arterioportal fistulas, causing arteriovenous shunting and protal hypertension, respectively. Abnormal blood flow is the proposed mechanism for the hepatic fibrosis and nodular regeneration. Hepatic fibrosis, by causing stenosis of large intrahepatic bile ducts, bile stasis, and secondary infection, is the hypothesized mechanism for calculus formation. Hepatolithiasis ultimately caused death from acute bacterial cholangitis and septicemia.     

Clinical and molecular genetic features of pulmonary hypertension in patients with hereditary hemorrhagic telangiectasia

BACKGROUND: Most patients with familial primary pulmonary hypertension have defects in the gene for bone morphogenetic protein receptor II (BMPR2), a member of the transforming growth factor beta (TGF-beta) superfamily of receptors. Because patients with hereditary hemorrhagic telangiectasia may have lung disease that is indistinguishable from primary pulmonary hypertension, we investigated the genetic basis of lung disease in these patients. METHODS: We evaluated members of five kindreds plus one individual patient with hereditary hemorrhagic telangiectasia and identified 10 cases of pulmonary hypertension. In the two largest families, we used microsatellite markers to test for linkage to genes encoding TGF-beta-receptor proteins, including endoglin and activin-receptor-like kinase 1 (ALK1), and BMPR2. In subjects with hereditary hemorrhagic telangiectasia and pulmonary hypertension, we also scanned ALK1 and BMPR2 for mutations. RESULTS: We identified suggestive linkage of pulmonary hypertension with hereditary hemorrhagic telangiectasia on chromosome 12q13, a region that includes ALK1. We identified amino acid changes in activin-receptor-like kinase 1 that were inherited in subjects who had a disorder with clinical and histologic features indistinguishable from those of primary pulmonary hypertension. Immunohistochemical analysis in four subjects and one control showed pulmonary vascular endothelial expression of activin-receptor-like kinase 1 in normal and diseased pulmonary arteries. CONCLUSIONS: Pulmonary hypertension in association with hereditary hemorrhagic telangiectasia can involve mutations in ALK1. These mutations are associated with diverse effects, including the vascular dilatation characteristic of hereditary hemorrhagic telangiectasia and the occlusion of small pulmonary arteries that is typical of primary pulmonary hypertension.     

Liver disease in patients with hereditary hemorrhagic telangiectasia

BACKGROUND: Hereditary hemorrhagic telangiectasia, or Rendu-Osler-Weber disease, is an autosomal dominant disorder characterized by angiodysplastic lesions (telangiectases and arteriovenous malformations) that affect many organs. Liver involvement in patients with this disease has not been fully characterized. METHODS: We studied the clinical findings and results of hemodynamic, angiographic, and imaging studies in 19 patients with hereditary hemorrhagic telangiectasia and symptomatic liver involvement. RESULTS: We evaluated 14 women and 5 men who ranged in age from 34 to 74 years. All but one of the patients had a hyperdynamic circulation (cardiac index, 4.2 to 7.3 liters per minute per square meter of body-surface area). In eight patients, the clinical findings were consistent with the presence of high-output heart failure. The cardiac index and pulmonary-capillary wedge pressure were elevated in the six patients in whom these measurements were performed. After a median period of 24 months, the condition of three of the eight patients had improved, four were in stable condition with medical therapy, and one had died. Six patients had manifestations of portal hypertension such as ascites or variceal bleeding. The hepatic sinusoidal pressure was elevated in the four patients in whom it was measured. After a median period of 19 months, the condition of two of the six patients had improved, and the other four had died. Five patients had manifestations of biliary disease, such as an elevated alkaline phosphatase level and abnormalities on bile duct imaging. After a median period of 30 months, the condition of two of the five had improved, the condition of one was unchanged, heart failure had developed in one, and one had died after an unsuccessful attempt at liver transplantation. CONCLUSIONS: In patients with hereditary hemorrhagic telangiectasia and symptomatic liver-involvement, the typical clinical presentations include high-output heart failure, portal hypertension, and biliary disease.     

Mutation analysis in Norwegian families with hereditary hemorrhagic telangiectasia: founder mutations in ACVRL1

Hereditary hemorrhagic telangiectasia (HHT, Osler–Weber–Rendu disease) is an autosomal dominant inherited disease defined by the presence of epistaxis and mucocutaneous telangiectasias and arteriovenous malformations (AVMs) in internal organs. In most families (～85%), HHT is caused by mutations in the ENG (HHT1) or the ACVRL1 (HHT2) genes. Here, we report the results of genetic testing of 113 Norwegian families with suspected or definite HHT. Variants in ENG and ACVRL1 were found in 105 families (42 ENG, 63 ACVRL1), including six novel variants of uncertain pathogenic significance. Mutation types were similar to previous reports with more missense variants in ACVRL1 and more nonsense, frameshift and splice‐site mutations in ENG. Thirty‐two variants were novel in this study. The preponderance of ACVRL1 mutations was due to founder mutations, specifically, c.830C>A (p.Thr277Lys), which was found in 24 families from the same geographical area of Norway. We discuss the importance of founder mutations and present a thorough evaluation of missense and splice‐site variants.     

Analysis of ALK-1 and endoglin in newborns from families with hereditary hemorrhagic telangiectasia type 2

ALK-1 (activin receptor-like kinase-1), a type I receptor of the transforming growth factor (TGF)-beta superfamily, is the gene mutated in hereditary hemorrhagic telangiectasia type 2 (HHT2) while endoglin is mutated in HHT1. Using a novel polyclonal antibody to ALK-1, we measured ALK-1 expression on human umbilical vein endothelial cells (HUVEC) of newborns from HHT families whose affected members had normal endoglin levels. ALK-1 levels were specifically reduced in three HUVEC with ALK-1 missense mutant codons, and normal in two newborns not carrying the missense mutations present in the clinically affected relatives. Levels were also normal in a HUVEC with deletion of S232 in the ATP binding site of ALK-1. Thus HHT2 appears to be associated with a loss of function of the mutant allele due to a reduction in either protein level or activity. We also report three new ALK-1 missense mutations leading to G48E/A49P, C344Y and E407D substitutions. In COS-1 transfected cells, ALK-1 was found in the TGF-beta1 and -beta3 receptor complexes in association with endoglin and TbetaRII, but not in activin receptor complexes containing endoglin. In HUVEC, ALK-1 was not detectable in the TGF-beta1 or -beta3 receptor complexes. However, in the absence of ligand, ALK-1 and endoglin interactions were observed by immunoprecipitation/western blot in HUVEC from normal as well as HHT1 and HHT2 patients. Our data suggest a transient association between these two proteins of the TGF-beta superfamily, both required at a critical level to ensure vessel wall integrity.     

Pulmonary arteriovenous fistulas in hereditary hemorrhagic telangiectasia

We reviewed all available chest X-rays of 95 patients with hereditary hemorrhagic telangiectasia (HHT). The diagnosis of pulmonary arteriovenous fistula (PF) had previously been made in 13 patients, nine of whom had been operated on. Another three cases were found in the review. The 16 patients with HHT and PF came from eight families, one of which contributed seven patients. Median observation time between the first and the latest chest X-ray examination was 11 years (range 1/2-35). Growth of the PF was seen in four patients and spontaneous regression in one. Four of the 16 patients with PF had symptoms consistent with cerebral embolism, while only two of the 79 patients without PF had such symptoms. This study is part of an epidemiological investigation of HHT--to our knowledge not carried out before. The calculated period prevalence of simultaneous HHT and PF in the decade 1964-74 in the county of Fyn (429 207 inhabitants) was 2.6 per 100 000.     

Age-related clinical profile of hereditary hemorrhagic telangiectasia in an epidemiologically recruited population

We report the results of a comprehensive and systematic clinical study of 324 patients with hereditary hemorrhagic telangiectasia, selected from a total of 1,270 cases recruited by epidemiological survey. In 94% of the cases, familial occurrence suggested autosomal dominant inheritance; maximum penetrance for at least one manifestation was 97%. Epistaxis was reported by 96% of the patients and, in more than 50%, developed before age 20. Heavy and frequent bleeding occurred mainly in middle-aged patients. Telangiectasia was documented in 74% of cases, half of whom were younger than 30 years. The frequency of involvement of the hands and wrists was 41%, and for the face, 33%. Visceral involvement was present in 25% of patients, with affected lungs and CNS in the young and gastrointestinal tract and liver in older patients. Symptomatic urinary tract involvement was seen in only two/324 patients. Involvement of other internal sites was not observed.     

Pulmonary capillary hemangiomatosis arising in hereditary hemorrhagic telangiectasia

Hereditary hemorrhagic telangiectasia (HHT), also known as Osler-Weber-Rendu syndrome, is an autosomal dominant inherited disease characterized by epistaxis, telangiectases, and visceral arteriovenous malformations that can lead to hemorrhage and other complications. We report the case of a 56-year-old female patient with HHT and pulmonary hypertension who died with intractable pulmonary and gastrointestinal bleeding. Autopsy revealed vascular malformations in the lungs, gastrointestinal tract, liver, spleen, and brain. Capillary proliferations in the pulmonary alveolar walls, characteristic of pulmonary capillary hemangiomatosis, were identified, as was evidence of pulmonary hypertensive arteriopathy. To our knowledge, this is the first report of pulmonary capillary hemangiomatosis arising in HHT. The histopathologic findings of HHT and pulmonary capillary hemangiomatosis are reviewed, and a possible role for diminished capillary expression of endothelial nitric oxide synthase is discussed.     

Nodular transformation of the liver in hereditary hemorrhagic telangiectasia

A case of hereditary hemorrhagic telangiectasia with prominent nodular transformation of the liver is described. The presence of enlarged arteries was documented morphometrically. Artery-to-portal vein shunts were also found. The association of abnormal vessels with hepatic nodules supports the hypothesis that abnormalities of blood flow cause nodular transformation. Nodular transformation may be the lesion that has heretofore been termed cirrhosis hepatis telangiectasia or atypical cirrhosis.     

Mutations in the ALK-1 gene and the phenotype of hereditary hemorrhagic telangiectasia in two large Danish families

Mutations in the ENG gene on chromosome 9 (HHT 1) and in the ALK-1 gene on chromosome 12 (HHT 2) have been reported as causes of hereditary hemorrhagic telangiectasia (HHT). HHT 1 has been correlated with a higher prevalence of pulmonary arteriovenous malformations than HHT 2. Other distinct phenotype-genotype correlations have not been described. The prevalence of HHT in the county of Fyn, Denmark, was 15.6 per 100,000 on January 1, 1995. All living patients and their first-degree relatives were invited to attend a detailed clinical examination and blood was drawn for mutation analysis. In two families mutations were identified in exon 8 of the ALK-1 gene. In family 6 we found a T1193A mutation. In this family a high prevalence of PAVM and severe GI bleeding was documented, while in family 8 with a C1120T mutation no individuals with PAVM were identified and only one patient had a history of severe GI bleeding. No mutations in the endoglin locus were found in either family.     

Likelihood ratios to assess genetic evidence for clinical significance of uncertain variants: hereditary hemorrhagic telangiectasia as a model

Clinical laboratories performing gene sequencing discover previously unreported and/or uncharacterized variants. Often these are missense or intronic mutations in which the contribution to disease cannot be predicted, and consequently these mutations are reported as variants of uncertain significance. Follow-up to assess family concordance is recommended by the American College of Medical Genetics to provide genetic evidence for clinical significance. Although family concordance studies show whether a variant segregates with disease in the family, the strength of evidence varies depending on the number and degree of relatedness of family members available for testing. We investigated a statistical model which accounts for the pedigree, inheritance patterns, and penetrance to determine the likelihood of a variant being a causative or deleterious mutation. We used hereditary hemorrhagic telangiectasia (HHT) as a model for an autosomal dominant disease. Pedigree data were transferred to MLINK, and a Bayesian analysis was calculated to determine the likelihood that a variant is causative of disease. In applying this analysis to HHT pedigrees we found Bayes Factors of variants showing odds in favor of causality ranging from approximately 4:1 to over 400:1. These numbers provide an objective measure of the strength of genetic evidence. Other parameters such as amino acid severity predictions, ortholog and paralog comparisons and functional assays can be included in the analysis to increase the evidence of causality.     

Gene expression fingerprinting for human hereditary hemorrhagic telangiectasia

Hereditary hemorrhagic telangiectasia (HHT) or Osler–Weber–Rendusyndrome is an autosomal dominant vascular disorder characterizedby telangiectases and internal arteriovenous malformations.It is caused by mutations in elements of the transforming growthfactor-ß (TGF-ß) receptor complex: endoglin,a co-receptor, responsible for HHT1, or ALK1 (activin receptor-likekinase 1), a type I receptor leading to HHT2. Recently, we haveestablished cultures of HHT endothelial cells, primary targetsof the disease. These cells showed deficient TGF-ßsignaling and angiogenesis, representing a useful human modelto study the molecular mechanism of this disease. To understandthe pathogenic mechanism underlying HHT, we have used totalRNA probes to compare HHT versus non-HHT cells by expressionmicroarrays. This work represents a systematic study to identifytarget genes affected in HHT cells. Given the similarity ofsymptoms in HHT1 and HHT2, special interest has been put onthe identification of common targets for both HHT types. Asa result, 277 downregulated and 63 upregulated genes were identifiedin HHT versus control cells. These genes are involved in biologicalprocesses relevant to the HHT pathology, such as angiogenesis,cytoskeleton, cell migration, proliferation and NO synthesis.The type of misregulated genes found in HHT endothelial cellslead us to propose a model of HHT pathogenesis, opening newperspectives to understand this disorder. Moreover, as the diseaseis originated by mutations in proteins of the TGF-ßreceptor complex, these results may be useful to find out targetsof the TGF-ß pathway in endothelium.