A case report of acute myocardial infarction with hereditary hemorrhagic telangiectasia.

Hereditary hemorrhagic telangiectasia (HHT) is an autosomal dominant disorder characterized by epistaxis, gastrointestinal bleeding, iron deficiency anemia, and arteriovenous malformations (AVMs) affecting the lungs, liver, and brain. Owing to its rarity and diagnostic challenges, early identification is often elusive. Underdiagnosis and prolonged diagnostic delays are prevalent. Here, we present the case of a 63-year-old male who presented with chest pain and was diagnosed with an ST-elevation myocardial infarction (STEMI). Subsequently, he underwent placement of a drug-eluting stent in the right coronary artery (RCA). However, recurrent postoperative epistaxis resulted in severe anemia, prompting further investigation leading to the diagnosis of hereditary hemorrhagic telangiectasia through comprehensive medical history and genetic testing. Future studies are warranted to evaluate reperfusion strategies in HHT patients presenting with myocardial infarction.

A rare case of spinal involvement in hereditary hemorrhagic telangiectasia.

INTRODUCTION: Here, we describe a rare case of a spinal arteriovenous fistula in a patient with known hereditary hemorrhagic telangiectasia (HHT) and spontaneous intraspinal hemorrhage. Furthermore, we provide a brief review of the literature on the formation of spinal arteriovenous malformations (AVM) in relation to this disease. CASE PRESENTATION: The case involves a 54-year-old male with known HHT. At the age of 49, the patient experienced recurrent cystitis. Urological evaluation ruled the cause to be neurological and subsequent imaging revealed a thoracic AVM. Four years later, the patient was admitted to A&E with chest pain and loss of function of the lower extremities and right arm, suspicious for ruptured aortic dissection. Trauma-CT excluded this and a final diagnosis of ruptured spinal AVM was made. Seven months post-injury, a spinal angiography was performed confirming the AVM. The remaining AVM was embolized under general anesthesia with acceptable results. DISCUSSION: Spinal involvement in HHT is exceedingly rare but remains an important differential diagnosis, especially when patients present autonomic symptoms as these could potentially progress to life-threatening complications. The literature and the presented case indicate the prudence of closing spinal AVMs in HHT in case of symptoms, including autonomic, such as bladder dysfunction.

Telangiectasias, recurrent epistaxis and a strong family history-a case of Osler- Weber-Rendu Syndrome in Pakistan.

Osler-Weber-Rendu syndrome or Hereditary Haemorrhagic Telangiectasia (HHT) is a rare condition, with very few reported cases, especially in Pakistan. As healthcare workers, we encounter multiple cases of recurrent epistaxis in the emergency as well as outpatient departments. However, patients are usually treated symptomatically without a thorough workup. HHT should be considered among the differentials for recurrent epistaxis, as a clinical diagnosis can be made with detailed family history and physical examination. Here is the case of a 58-year-old male who presented to the Gastroenterology OPD, Combined Military Hospital, Lahore, in November 2021, with complaints of generalised weakness and blood in stools. He had a history of recurrent epistaxis and telangiectasias, and further inquiry revealed a strong family history of similar symptoms. He was diagnosed as a case of Osler-Weber- Rendu Syndrome. Informed consent was taken from the patient prior to the writing of the manuscript.

Personalised stroke evaluation and management: tailoring individualised patient care for hereditary haemorrhagic telangiectasia.

SummaryHereditary haemorrhagic telangiectasia (HHT) has an estimated prevalence of 1 in 5000-8000 individuals globally with pulmonary arteriovenous malformations (PAVMs) affecting approximately 15%-50% of HHT patients. Ischaemic stroke is a known complication of PAVMs that affects ≤30% of patients with PAVMs. Studies have shown that patients with PAVMs have ischaemic stroke a decade earlier than routine stroke. The predominant mechanism of ischaemic stroke in HHT patients is paradoxical embolism due to PAVMs, but most HHT-related PAVMs are asymptomatic. Additionally, HHT is often underdiagnosed in patients and poses a challenge to physicians due to its rarity. We present a case of a patient with ischaemic stroke who was subsequently diagnosed with HHT and found to have a PAVM on further evaluation. This case highlights the importance of using an individualised patient-centred stroke evaluation and screening for PAVMs in patients who had a stroke with possible or suspected HHT and definite HHT.

Hereditary hemorrhagic telangiectasia diagnosis: A case report.

This case report presents a 13-year-old patient with a lung nodule identified on a chest radiograph in the emergency department during an evaluation of knee and side pain after a fall. The patient had nosebleeds, family history of hereditary hemorrhagic telangiectasia (HHT) and after chest computed tomography with angiography, the nodule was defined as a single pulmonary arteriovenous malformation (PAVM). Neither parent nor patient had been evaluated for HHT, an autosomal dominant disease, despite the family history. This patient satisfied the clinical criteria for the diagnosis and had a confirmatory genetic test, which led to diagnosis in mother also. The patient's PAVMs were treated, decreasing the risk of life threatening complications. Diagnosing HHT in children is often delayed or missed, even in families with HHT, as in this case report. Without any physical signs or clinical symptoms, families and healthcare providers often dismiss the possibility of the diagnosis. Children with HHT are at the same risk for complications of stroke, anemia, hypoxemia, heart failure and increased morbidity as adults. It is essential to recognize the importance of family history when evaluating children in primary care and urgent settings, as this patient's diagnosis was delayed 13 years. Awareness of HHT signs and symptoms are essential to early referral to an HHT specialist, for diagnosis and management.

Un caso pediátrico de telangiectasia hemorrágica hereditaria (Síndrome de Rendu-Osler-Weber) con compromiso pulmonar / A pediatric case of hereditary hemorrhagic telangiectasia (Rendu-Osler-Weber Syndrome) with pulmonary involvement

La telangiectasia hemorrágica hereditaria (HHT), o síndrome de Rendu-Osler-Weber, se considera dentro del grupo de las enfermedades raras, pues afecta a 1 de cada 3.000 a 8.000 individuos. Tiene un patrón de herencia autosómica dominante y la mayor parte de los casos se debe a una alteración en la codificación de los genes endoglina (ENG) y activina receptor-like kinase 1 (ALK1), dando origen a los tipos 1 y 2, respectivamente. Esta alteración genética se traduce en una displasia del endotelio de la pared vascular debido a haploinsuficiencia para endoglina y se manifiesta clínicamente con epistaxis a repetición, telangiectasias mucocutáneas y malformaciones arteriovenosas (MAV) viscerales. A continuación, se presenta el caso clínico de una paciente pediátrica de 11 años de edad que se manifestó por disnea e hipoxemia severa debido a múltiples fístulas arteriovenosas pulmonares.

Hereditary hemorrhagic telangiectasia (HHT), or Rendu-Osler-Weber syndrome, is considered among rare diseases, as it affects 1 in every 3,000 to 8,000 individuals. It follows an autosomal dominant inheritance pattern, and most cases are due to alterations in the coding of the endoglin (ENG) and activin receptor-like kinase 1 (ALK1) genes, leading to types 1 and 2, respectively. This genetic alteration results in vascular endothelial dysplasia due to haploinsufficiency for endoglin and clinically manifests with recurrent epistaxis, mucocutaneous telangiectasias, and visceral arteriovenous malformations (AVMs). Herein, we present the clinical case of an 11-year-old pediatric patient who exhibited severe dyspnea and hypoxemia due to multiple pulmonary arteriovenous fistulas.

An Splenic Artery Aneurysm and Focal Nodular Hyperplasia Associated with an Abdominal Vascular Abnormality of Hereditary Hemorrhagic Telangiectasia.

In October 2021, a 51-year-old woman developed a skin rash. Abdominal computed tomography revealed a large splenic artery aneurysm and an intrahepatic portovenous shunt. As her splenic artery aneurysm was at risk of rupture, she was referred to the Kindai University Hospital and underwent coiling surgery. In October 2023, approximately two years after she had been initially referred, contrast-enhanced ultrasound revealed findings suggestive of focal nodular hyperplasia. No reports have confirmed the occurrence of liver masses in patients with hereditary hemorrhagic telangiectasia, which is considered to be an interesting finding when investigating the mechanism of tumor development.

Genome sequencing identify chromosome 9 inversions disrupting ENG in 2 unrelated HHT families.

Hereditary hemorrhagic telangiectasia (HHT), also known as Rendu-Osler-Weber disease, is a dominant inherited vascular disorder. The clinical diagnosis is based on the Curaçao criteria and pathogenic variants in the ENG and ACVRL1 genes are responsible for most cases of HHT. Four families with a negative targeted gene panel and selected by a multidisciplinary team were selected and whole-genome sequencing was performed according to the recommendations of the French National Plan for Genomic Medicine. Structural variations were confirmed by standard molecular cytogenetic analysis (FISH). In two families with a definite diagnosis of HHT, we identified two different paracentric inversions of chromosome 9, both disrupting the ENG gene. These inversions are considered as pathogenic and causative for the HHT phenotype of the patients. This is the first time structural variations are reported to cause HHT. As such balanced events are often missed by exon-based sequencing (panel, exome), structural variations may be an under-recognized cause of HHT. Genome sequencing for the detection of these events could be suggested for patients with a definite diagnosis of HHT and in whom no causative pathogenic variant was identified.

Endoglin mutants retained in the endoplasmic reticulum exacerbate loss of function in hereditary hemorrhagic telangiectasia type 1 (HHT1) by exerting dominant negative effects on the wild type allele.

Hereditary hemorrhagic telangiectasia (HHT) is an autosomal dominant disorder affecting 1 in 5000-8000 individuals. Hereditary hemorrhagic telangiectasia type 1 (HHT1) is the most common HHT and manifests as diverse vascular malformations ranging from mild symptoms such as epistaxis and mucosal and cutaneous telangiectases to severe arteriovenous malformations (AVMs) in the lungs, brain or liver. HHT1 is caused by heterozygous mutations in the ENG gene, which encodes endoglin, the TGFß homodimeric co-receptor. It was previously shown that some endoglin HHT1-causing variants failed to traffic to the plasma membrane due to their retention in the endoplasmic reticulum (ER) and consequent degradation by ER-associated degradation (ERAD). Endoglin is a homodimer formed in the ER, and we therefore hypothesized that mixed heterodimers might form between ER-retained variants and WT protein, thus hampering its maturation and trafficking to the plasma membrane causing dominant negative effects. Indeed, HA-tagged ER-retained mutants formed heterodimers with Myc-tagged WT endoglin. Moreover, variants L32R, V105D, P165L, I271N and C363Y adversely affected the trafficking of WT endoglin by reducing its maturation and plasma membrane localization. These results strongly suggest dominant negative effects exerted by these ER-retained variants aggravating endoglin loss of function in patients expressing them in the heterozygous state with the WT allele. Moreover, this study may help explain some of the variability observed among HHT1 patients due to the additional loss of function exerted by the dominant negative effects in addition to that due to haploinsufficiency. These findings might also have implications for some of the many conditions impacted by ERAD.

High risk of ischaemic stroke amongst patients with hereditary haemorrhagic telangiectasia.

BACKGROUND AND PURPOSE: Hereditary haemorrhagic telangiectasia (HHT) is a genetic disease with fragile blood vessels and vascular malformations, potentially causing neurological manifestations, including stroke and cerebral abscesses. The study aimed to investigate neurological manifestations in the Danish HHT database, focusing on pulmonary arteriovenous malformations (PAVMs) as a risk factor for cerebral events. METHODS: Retrospective analysis of the Danish HHT database was conducted, cross-referencing neurological outcomes with the Danish Apoplexy Register for accuracy. Patients were stratified by HHT type. Primary outcomes included ischaemic stroke, transient ischaemic attack and cerebral haemorrhage. Secondary outcomes comprised age, age at HHT diagnosis, age at cerebral ischaemic event, and PAVM and cerebral arteriovenous malformation status. RESULTS: Six hundred and sixty-four HHT patients were included. PAVM was diagnosed in 54% of patients, with higher prevalence in HHT type 1 (70%) compared to HHT type 2 (34%) and juvenile polyposis HHT (66%). Ischaemic stroke or transient ischaemic attack occurred in 12.5%, with a higher risk associated with macroscopic PAVM. Logistic regression showed a nearly 10 times increased risk of ischaemic stroke with macroscopic PAVM. Cerebral abscesses occurred in 3.2% of patients, all with macroscopic PAVM. Incomplete PAVM closure increased cerebral abscess risk. CONCLUSION: This study provides valuable insights into the prevalence of neurological manifestations and vascular events in HHT patients. The presence of PAVM was associated with an increased risk of ischaemic stroke, highlighting the importance of early screening and intervention. The findings emphasize the need for comprehensive management strategies targeting both vascular and neurological complications in HHT patients, especially regarding secondary stroke prevention.

A novel frameshift mutation of the endoglin(ENG) gene causes hereditary hemorrhagic telangiectasia in a Chinese family.

PURPOSE: Hereditary hemorrhagic telangiectasia (HHT) is a dominantly inherited disorder that involves epistaxis, mucocutaneous telangiectases, and visceral arteriovenous malformations (AVMs). This study aims to investigate the genetic causes in a Chinese family with HHT. METHODS: HHT was confirmed according to Curaçao's diagnostic criteria. Three patients diagnosed with HHT and healthy members were recruited. Whole-exome sequencing (WES) and sanger sequencing were performed to define the patient's genetically pathogenic factor. RESULTS: The proband presented with recurrent epistaxis, hepatopulmonary arteriovenous malformation, and adenocarcinoma. A novel frameshift mutation (c.1376_1377delAC, p.H459Lfs*41) of the ENG gene was revealed in affected individuals by WES. There was no report of this variant and predicted to be highly damaging by causing truncation of the ENG protein. CONCLUSION: We report a novel variant in the ENG gene in Chinese that extends the mutational and phenotypic spectra of the ENG gene, and also demonstrates the feasibility of WES in the application of genetic diagnosis of HHT.

Understanding hereditary hemorrhagic telangiectasia: From genetic anomalies to systemic manifestations, quality of life, and epistaxis management-Exploring the otolaryngologist's integral role.

Hereditary hemorrhagic telangiectasia (HHT), also known as Osler-Rendu-Weber syndrome, is a rare autosomal dominant disorder characterized by vascular malformations. This comprehensive review aimed to provide an overview and summarize various aspects of HHT, including the genetic abnormalities, complications associated with visceral arteriovenous malformations (AVMs), prognosis of HHT, quality of life (QOL), and treatment of epistaxis. In addition, this review highlights the challenges in diagnosing HHT and emphasizes the critical role of otolaryngologists in the early detection of HHT. Otolaryngologists can refer patients with refractory epistaxis for AVM screening to expedite intervention. Mutation of the genes involved in the transforming growth factor-ß signaling pathway leads to the incidence of HHT, resulting in the formation of abnormal blood vessel formation. These vascular malformations commonly manifest as telangiectasia on the skin and mucous membranes; however, epistaxis remains the hallmark symptom of HHT. The impact of HHT goes beyond the visible symptoms and often includes the formation of life-threatening visceral AVMs in the lungs, liver, and brain. The prognosis of patients with HHT is closely related to the development of these complications, necessitating timely diagnosis and intervention. Refractory epistaxis diminishes the QOL of patients with HHT. The management of epistaxis ranges from conservative measures to advanced interventions such as prevention, conservative treatments, ablation, surgical procedures, and the administration of anti-angiogenic agents. However, effective management requires a multidisciplinary approach. The diagnosis of HHT remains challenging due to its variable presentation and lack of awareness among physicians. This review highlights the importance of reducing the duration between symptom onset and diagnosis. Otolaryngologists who are experienced in the management of refractory epistaxis can aid in identifying potential cases of HHT. They can facilitate the initiation of screening for visceral AVMs via prompt recognition of the signs and symptoms of HHT, contributing to improved patient outcomes. Early detection and intervention through screening can extend the life expectancy of patients with HHT to levels comparable with that of the general population. In conclusion, this review provides insight into various aspects of HHT and emphasizes the importance of timely diagnosis and intervention in the mitigation of the potentially life-threatening complications associated with this disorder. Otolaryngologists play a critical role in this process, serving as gatekeepers to the identification of cases of HHT and implementation of appropriate screening and management pathways, thereby improving the life expectancy and QOL of patients.

Pulmonary arteriovenous malformations in patients with previous brain abscess: a cross-sectional population-based study.

BACKGROUND AND PURPOSE: Pulmonary arteriovenous malformations (PAVMs) may cause recurrent brain abscess. The primary aim was to determine the prevalence of PAVM amongst survivors of brain abscess. The proportion with cardiac right-to-left shunts was also assessed post hoc. METHODS: This was a cross-sectional population-based study of adult (≥18 years) survivors of cryptogenic bacterial brain abscess in Denmark from 2007 through 2016. Patients were invited for bubble-echocardiography to detect vascular right-to-left shunting and, if abnormal, subsequent computed tomography thorax for diagnosis of PAVM. Data are presented as n/N (%) or median with interquartile range (IQR). RESULTS: Study participation was accepted by 47/157 (30%) eligible patients amongst whom two did not appear for scheduled bubble-echocardiography. The median age of participants was 54 years (IQR 45-62) and 19/57 (33%) were females compared with 59 years (IQR 48-68, p = 0.05) and 41/85 females (48%, p = 0.22) in non-participants. Bubble-echocardiography was suggestive of shunt in 10/45 (22%) participants and PAVM was subsequently confirmed by computed tomography in one patient with grade 1 shunting. The corresponding prevalence of PAVM was 2% (95% confidence interval 0.06-11.8) amongst all examined participants. Another 9/45 (20%) were diagnosed with patent in persistent foramen ovale (n = 8) or atrial septum defect (n = 1), which is comparable with the overall prevalence of 25% amongst adults in the Danish background population. CONCLUSIONS: Undiagnosed PAVM amongst adult survivors of cryptogenic bacterial brain abscess is rare but may be considered in select patients. The prevalence of cardiac right-to-left shunts amongst brain abscess patients corresponds to the prevalence in the general population.

Prevalence and Predictors of Hereditary Hemorrhagic Telangiectasia and Capillary-Malformation Arteriovenous Malformation Syndrome Among Children with Neurovascular Malformations.

OBJECTIVE: To investigate the prevalence and predictors of hereditary hemorrhagic telangiectasia (HHT) and capillary-malformation arteriovenous malformation (CM-AVM) syndrome among children with no prior personal or family history of these diseases who presented with an arteriovenous shunt lesion. STUDY DESIGN: A retrospective chart review was completed on patients aged 0 through 21 years with arteriovenous shunt lesions evaluated at our Cerebrovascular Center. Diagnosis of definite or suspected HHT or CM-AVM was based on clinical features and genetic testing. Associations between final diagnosis and type and number of lesions, epistaxis, telangiectasias, CM, and pulmonary AVMs were assessed. RESULTS: Eighty-nine patients were included. Thirteen (14.6%) had definite HHT, 11 (12.4%) suspected HHT, and 4 (4.5%) definite CM-AVM. Having ≥2 episodes of epistaxis/year and ≥ 2 sites with telangiectasias were each associated with definite HHT (P < .001). Having ≥ 2 CM was associated with definite CM-AVM (P < .001). Pulmonary AVM was associated with increased odds of having definite HHT (OR = 6.3, 95% CI: 1.2-33.4). Multiple lesions (OR = 24.5, 95% CI: 4.5-134.8) and arteriovenous fistulas (OR = 6.2, 95% CI: 1.9-20.3) each increased the likelihood of having definite HHT or CM-AVM. Genetic testing was positive in 31% of patients tested. CONCLUSIONS: We recommend that children with neurovascular shunt lesions be offered genetic testing and undergo further evaluation for HHT and CM-AVM. Awareness and early diagnosis of these conditions is a critical step toward improving long-term outcomes and preventing disease-associated complications.

[Iron deficiency anemia in a patient with hereditary hemorrhagic telangiectasia. Case report].

Rendu-Osler-Weber disease or hereditary hemorrhagic telangiectasia (HHT) is a rare autosomal dominant disease. It is characterized by vascular dysplasia with the formation of telangiectasias on the skin, mucous membranes of the respiratory and digestive tracts, arteriovenous malformations (AVMs) in the internal organs, which is manifested by bleeding. Diagnosis is based on Curacao criteria: recurrent and spontaneous nosebleeds, multiple telangiectases on the characteristic localizations, AVMs in one or more of the internal organs, a family history of HHT (i.e. first-degree relative who meets these same criteria for definite HHT). Therapy is aimed at preventing and stopping gastrointestinal, nosebleeds, correction of iron deficiency anemia. A promising method of therapy is the use of angiogenesis inhibitors, in particular bevacizumab. The article presents a description of a clinical case of HHT in a 49-year-old woman with telangiectisia on the mucous membrane of the tongue, gastrointestinal tract and liver AVMs.

[Prevalencia de la Telangiectasia Hemorrágica Hereditaria: estudio de base poblacional en la Comunitat Valenciana (España).] / Prevalence of Hereditary Hemorrhagic Telangiectasia: a population-based study in the Valencian region (Spain).

OBJECTIVE: The Hereditary Haemorrhagic Telangiectasia (HHT) is a low prevalence disease which presents heterogeneous signs and symptoms and just few population-based epidemiological studies are available. The aims of this paper were to describe the sociodemographic characteristics of people affected by HHT in the Valencian Region (VR), to determine its prevalence and mortality rate, and to analyse the sources of recruitment and verification tests used by the Rare Diseases Information System of the VR (SIER-CV). METHODS: Cross-sectional observational epidemiological study of HHT prevalent cases between 2010-2019 in SIER-CV was performed. The distribution of sociodemographic and clinical characteristics were determined, the prevalence and mortality rates, and the sources of recruitment and verification tests used by SIER-CV were analysed. Statistical analysis was performed using Stata (version 16.1) and Microsoft Excel Office. RESULTS: During 2010-2019, two hundred cases were identified, 55.5% were female. The mean ages were: 56.8 years at recruitment and 50.9 years at diagnosis. 48.4% of cases were diagnosed between thirty-six/sixty-four years of age. 25.5% died, with a mean age of 76.6 years, identifying statistically significant differences above the age of 64. The prevalence was 39.6/1,000,000 inhabitants and the crude mortality rate was 10.1/1,000,000 inhabitants. 95.5% of cases were recruited from the Hospital discharges database and the most frequent verification test was the clinical basis (45.7%). CONCLUSIONS: The increasing trend in prevalence coincides with a better knowledge of HHT, which favours its detection, and also with dying at older ages. To describe the situation of HHT in the VR facilitates its health management and contributes to the establishment of the relevant health policies for the HHT. The need to promote genetic diagnosis and to incorporate the Primary Care Clinical History as a source of recruitment in the population-based registries has been shown.

OBJECTIVE: La Telangiectasia Hemorrágica Hereditaria (THH) es una enfermedad de baja prevalencia, que se presenta con signos y síntomas muy heterogéneos y de la que apenas se dispone de estudios epidemiológicos de base poblacional. Los objetivos de este estudio fueron describir las características sociodemográficas de las personas afectadas por THH en la Comunitat Valenciana (CV), determinar su prevalencia y mortalidad, y analizar las fuentes de captación y pruebas de verificación utilizadas por el Sistema de Información de Enfermedades Raras de la CV (SIER-CV). METHODS: Se realizó un estudio epidemiológico observacional transversal de casos prevalentes de THH durante 2010-2019 en el SIER-CV. Se determinó la distribución de las características sociodemográficas y clínicas, la prevalencia y mortalidad, y se analizaron las fuentes de captación y pruebas de verificación utilizadas por SIER-CV. El análisis estadístico de los datos se realizó mediante el programa Stata (versión 16.1) y Microsoft Excel Office. RESULTS: Durante 2010-2019 se identificaron doscientos casos, de los que el 55,5% eran mujeres. Las edades medias fueron: de captación 56,8 años, y de diagnóstico 50,9 años. El 48,4% fueron diagnosticados entre los treinta y seis, y los sesenta y cuatro años. Fallecieron el 25,5%, con 76,6 años de edad media, identificándose diferencias estadísticamente significativas en mayores de sesenta y cuatro años. La prevalencia fue 39,6 por cada millón de habitantes y la tasa cruda de mortalidad de 10,1 por cada millón de habitantes. El 95,5% se captaron por el Conjunto Mínimo Básico de Datos y la prueba de verificación más frecuente fue la base clínica (45,7%). CONCLUSIONS: La tendencia ascendente de la prevalencia coincide con un mejor conocimiento de la THH, que facilita la detección de casos, y también con fallecimientos en edades avanzadas. Describir la situación de la THH en la CV facilita su manejo sanitario y contribuye al establecimiento de las políticas sanitarias correspondientes. Se muestra la necesidad de favorecer el diagnóstico genético e incorporar la Historia de Atención Primaria como fuente de captación en los registros poblacionales.

Hereditary haemorrhagic telangiectasia and SMAD4 mutation in a patient with complex single ventricle heart disease.

We report a case of hypoplastic left heart syndrome and with subsequent aortopathy and then found to have hereditary haemorrhagic telangiectasia/juvenile polyposis syndrome due to a germline SMAD4 pathologic variant. The patient's staged palliation was complicated by the development of neoaortic aneurysms, arteriovenous malformations, and gastrointestinal bleeding thought to be secondary to Fontan circulation, but workup revealed a SMAD4 variant consistent with hereditary haemorrhagic telangiectasia/juvenile polyposis syndrome. This case underscores the importance of genetic modifiers in CHD, especially those with Fontan physiology.