Frequency of de novo variants and parental mosaicism in vascular Ehlers–Danlos syndrome

The impact of Marfan syndrome and Ehlers-Danlos syndrome on the risk of penile fracture in patients between 18 and 45 years

BACKGROUND

Despite knowledge of the pathophysiology and clinical complications of connective tissue diseases (CTD), little is known regarding their impact on men's sexual health disorders.

AIM

To investigate the prevalence of penile fracture (PF) in patients with Ehlers-Danlos Syndrome (EDS) and Marfan syndrome (MFS) in comparison with disease-free controls between 18 and 45 years of age.

METHODS

A multicenter, international, electronic health record network (TriNetX) was queried to identify adult male patients (between 18 and 45 years) with or without EDS and MFS between 1993 and 2023 using ICD-10 codes. The prevalence of PF was compared between patients with and without the diseases of interest. Prevalence ratios (PR) were generated with 95% confidence intervals.

OUTCOME

Prevalence of PF in patients with EDS and MFS when compared to disease-free controls.

RESULTS

The number of patients with EDS, MFS, and control groups was 8060, 8642, and 20 184 547, respectively, with a mean age of 27.8 ± 7.58, 28.6 ± 7.4, and 31.6 ± 8.04 years. Men with EDS had a higher prevalence of PF (PR 30.18, 95% CI [17.08-53.19]; P < 0.0001). Similarly, men with MFS had a higher prevalence of PF (PR 23.4, 95% CI [12.6-43.7]; P < 0.0001).

CLINICAL IMPLICATIONS

This study demonstrates an association between CTD and men's sexual health disorders. It may be important to counsel such men about the risks of PF.

STRENGTHS AND LIMITATIONS

This is the largest study to date to demonstrate an association between CTD and men's sexual health disorders. While the large sample sizes in this study contribute to the robustness of the findings, the study is limited by the use of a claims-based dataset, which does not provide further details about disease course and complications, and the use of a univariate analysis only.

CONCLUSIONS

Patients with EDS and MFS are possibly at an elevated risk for PF. Due to the limitations of the TriNetX database, the analysis was limited to a univariate one, thus limiting the ability to control for confounders and limiting the generalizability of these findings. Further prospective research is needed to corroborate these findings.

Epileptic seizures revealing tuberous sclerosis in a tropical environment: A study of 12 case series

Background

Epilepsy remains a significant public health concern in Sub-Saharan Africa (SSA) where diverse etiological factors contribute to its prevalence. Among these factors are conditions originating from the neuroectoderm, such as tuberous sclerosis. Insufficient medical attention and a lack of comprehensive multidisciplinary care contribute to its under-recognition.

Materials and methods

We conducted a retrospective descriptive study, involving 12 patients admitted to the neurology and pediatric departments of the University Hospital Ignace Deen between 2010 and 2022 due to recurring epileptic seizures. Subsequently, these patients were diagnosed with Tuberous sclerosis using the Schwartz 2007 criteria. The aim of this study is to reassess this condition from a clinical and paraclinical point of view in a tropical environment.

Results

Tuberous sclerosis, also known as Bourneville disease, was diagnosed in 12 patients exhibiting focal motor seizures and complex focal seizures likely associated with cortical and subcortical tubers detectable by EEG and neuroimaging, including CT and MRI. Delayed treatment resulted in varying degrees of mental decline. Additionally, some patients displayed cardiac hamartomas and intracranial posterior and anterior aneurysms as minor diagnostic indicators.

Conclusion

The study reveals a consistent clinical presentation accompanied by deteriorating neurological and psychological symptoms attributed to delayed multidisciplinary management. These findings are utilized to assess therapeutic strategies and prognostic outcomes.

Comparative analysis of in-silico tools in identifying pathogenic variants in dominant inherited retinal diseases

Inherited retinal diseases (IRDs) are a group of rare genetic eye conditions that cause blindness. Despite progress in identifying genes associated with IRDs, improvements are necessary for classifying rare autosomal dominant (AD) disorders. AD diseases are highly heterogenous, with causal variants being restricted to specific amino acid changes within certain protein domains, making AD conditions difficult to classify. Here, we aim to determine the top-performing in-silico tools for predicting the pathogenicity of AD IRD variants. We annotated variants from ClinVar and benchmarked 39 variant classifier tools on IRD genes, split by inheritance pattern. Using area-under-the-curve (AUC) analysis, we determined the top-performing tools and defined thresholds for variant pathogenicity. Top-performing tools were assessed using genome sequencing on a cohort of participants with IRDs of unknown etiology. MutScore achieved the highest accuracy within AD genes, yielding an AUC of 0.969. When filtering for AD gain-of-function and dominant negative variants, BayesDel had the highest accuracy with an AUC of 0.997. Five participants with variants in NR2E3, RHO, GUCA1A, and GUCY2D were confirmed to have dominantly inherited disease based on pedigree, phenotype, and segregation analysis. We identified two uncharacterized variants in GUCA1A (c.428T>A, p.Ile143Thr) and RHO (c.631C>G, p.His211Asp) in three participants. Our findings support using a multi-classifier approach comprised of new missense classifier tools to identify pathogenic variants in participants with AD IRDs. Our results provide a foundation for improved genetic diagnosis for people with IRDs.

Genetic testing in cardiovascular disease

Cardiovascular disease (CVD) is the leading cause of morbidity and mortality globally and is responsible for an estimated one-third of deaths as well as significant morbidity and health care utilisation. Technological and bioinformatic advances have facilitated the discovery of pathogenic germline variants for some specific CVDs, including familial hypercholesterolaemia, cardiomyopathies and arrhythmic syndromes. Use of these genetic tests for earlier disease identification is increasing due, in part, to decreasing costs, Medicare rebates, and consumer comfort with genetic testing. However, CVDs that occur more commonly, including coronary artery disease and atrial fibrillation, do not display monogenic inheritance patterns. Genetically, these diseases have generally been associated with many genetic variants each with a small effect size. This complexity can be expressed mathematically as a polygenic risk score. Genetic testing kits that provide polygenic risk scoring are becoming increasingly available directly to private-paying consumers outside the traditional clinical setting. An improved understanding of the evidence of genetics in CVD will offer clinicians new opportunities for individualised risk prediction and preventive therapy.

Case report: A novel COL3A1 variant in a Colombian patient with isolated cerebrovascular involvement in vascular Ehlers-Danlos syndrome

Introduction

To date, approximately 600 unique pathogenic variants have been reported in COL3A1 associated with vascular Ehlers-Danlos syndrome (vEDS). The objective of this study was to describe a patient with a novel variant in COL3A1 associated with vEDS.

Case report

We describe the clinical history and thorough phenotyping of a patient with brain aneurysms and identified a novel pathogenic variant in COL3A1. This male patient reported transient focal neurologic symptoms. Physical examination showed abnormal atrophic scarring, horizontal stretch marks under the arms, and an acrogeric appearance of the skin of the hands and feet. Brain imaging revealed extensive dilation of both internal carotids and the vertebrobasilar system. Molecular analysis identified a variant in COL3A1 (NM_000090.4):c.3058G>T p.(Gly1020Cys), which was classified as likely pathogenic. Currently, the patient has never had an event concerning dissection/rupture of tissues that could be affected in this condition.

Conclusion

This report demonstrates that exhaustive evaluation with clinical and genetic approaches should be considered in patients with vascular abnormalities. vEDS has a variable clinical presentation and often goes unrecognized, even though it is related to life-threatening complications and a shortened life expectancy. Diagnosis confirmed by genetic testing is crucial to determining appropriate surveillance, prevention, treatment, and genetic counseling.

The role of cutaneous manifestations in the diagnosis of the Ehlers-Danlos syndromes

The Ehlers-Danlos syndromes (EDS) comprise a group of inherited connective tissue disorders presenting with features of skin hyperextensibility, joint hypermobility, abnormal scarring and fragility of skin, blood vessels and some organs. The disease is generally diagnosed through the cluster of clinical features, though the addition of genetic analysis is the gold standard for diagnosis of most subtypes. All subtypes display skin manifestations, which are essential to the accurate clinical diagnosis of the condition. Furthermore, cutaneous features can be the first and/or only presenting feature in some cases of EDS and thus understanding these signs is vital for diagnosis. This review focuses on particular cutaneous features of each EDS subtype and their clinical importance. Provision of a specific diagnosis is important for management, prognosis and genetic counselling, often for family members beyond the individual.

The dysmorphic phenotype in vascular Ehlers Danlos syndrome

The Ehlers Danlos syndromes are identified by their connective tissue features and are not rich in dysmorphic handles. Vascular Ehlers Danlos syndrome (vEDS) however, is characterised by a recognisable phenotypic constellation of internal and external dysmorphology. This review charts the paediatric and adult phenotypes of vEDS due primarily to COL3A1 gene variants and the potential recognition of some other EDS subtypes, including COL1A1 and COL25A1 that can present with vEDS-like features, with certain dysmorphic handles as clues to the diagnosis and the adjunct of gene testing in patients presenting with vEDS features.

Multi-exon COL5A1 deletion in a child with classical Ehlers-Danlos syndrome: A case report expanding the allelic spectrum and showing evidence of parental gonosomal mosaicism

Classical Ehlers-Danlos syndrome (cEDS) is a rare inherited autosomal dominant connective tissue disorder with core clinical features including skin hyperextensibility, abnormal scarring, and generalized joint hypermobility. Classical EDS is predominantly caused by small pathogenic variants in the genes COL5A1 and COL5A2 and occasionally by a COL1A1 point mutation p.(Arg312Cys), while gross deletions or duplications are uncommon. Gonosomal mosaicism is thought to be exceedingly rare with only two cases reported in the literature. We report a child with cEDS due to a rare gross deletion of exons 2-65 in the COL5A1 gene, inherited from an unaffected mosaic father. The level of mosaicism in the father was approximately 43% in leucocyte cells and 30% in DNA extracted from skin. Our results expand the allelic spectrum of cEDS variants and suggest that parental mosaicism needs to be considered in patients with suspected cEDS, given its implication for genetic counseling.

The False Dawn of Polygenic Risk Scores for Human Disease Prediction

Polygenic risk scores (PRSs) are being constructed for many diseases and are presented today as a promising avenue in the field of human genetics. These scores aim at predicting the risk of developing a disease by leveraging the many genome-wide association studies (GWAS) conducted during the two last decades. Important investments are being made to improve score estimates by increasing GWAS sample sizes, by developing more sophisticated methods, and by proposing different corrections for potential biases. PRSs have entered the market with direct-to-consumer companies proposing to compute them from saliva samples and even recently to help parents select the healthiest embryos. In this paper, we recall how PRSs arose and question the credit they are given by revisiting underlying assumptions in light of the history of human genetics and by comparing them with estimated breeding values (EBVs) used for selection in livestock.

Detection of germline mosaicism in fathers of children with intellectual disability syndromes caused by de novo variants

Background

De novo variants are a common cause to rare intellectual disability syndromes, associated with low recurrence risk. However, when such variants occur pre‐zygotically in parental germ cells, the recurrence risk might be higher. Still, the recurrence risk estimates are mainly based on empirical data and the prevalence of germline mosaicism is often unknown.

Methods

To establish the prevalence of mosaicism in parents of children with intellectual disability syndromes caused by de novo variants, we performed droplet digital PCR on DNA extracted from blood (43 trios), and sperm (31 fathers).

Results

We detected low‐level mosaicism in sperm‐derived DNA but not in blood in the father of a child with Kleefstra syndrome caused by an EHMT1 variant. Additionally, we found a higher level of paternal mosaicism in sperm compared to blood in the father of a child with Gillespie syndrome caused by an ITPR1 variant.

Conclusion

By employing droplet digital PCR, we detected paternal germline mosaicism in two intellectual disability syndromes. In both cases, the mosaicism level was higher in sperm than blood, indicating that analysis of blood alone may underestimate germline mosaicism. Therefore, sperm analysis can be clinically useful to establish the recurrence risk for parents and improve genetic counselling.

A systematic study of mosaicism in heritable thoracic aortic aneurysm and dissection

Mosaicisms are often overlooked in routine molecular diagnosis. Although not common, they are of great significance for accurate diagnosis and genetic counseling. In this study, we systematically evaluated the frequency of mosaicisms in both asymptomatic parents and affected patients with thoracic aortic aneurysm and dissection (TAAD). Next-generation sequencing (NGS) data from 1085 patients was reanalyzed with a more lenient allele frequency to detect potential mosaic variants. In addition, parental mosaicisms were investigated in 80 TAAD families. Finally, a total of six mosaic variants were detected in our cohort. Three of them were identified in symptomatic patients and three were in asymptomatic parents. Notably, a low-level mosaic variant in TGFB2 was detected combined with a causative FBN1 variant in patient AD2001, which might partially explain the clinical heterogeneity in his family. Our study hinted that it is necessary and feasible to implement mosaicism analysis in routine molecular diagnosis.

Gonosomal Mosaicism for a Novel COL5A1 Pathogenic Variant in Classic Ehlers-Danlos Syndrome

(1) Background: Classic Ehlers-Danlos syndrome (cEDS) is a heritable connective tissue disorder characterized by joint hypermobility and skin hyperextensibility with atrophic scarring. Many cEDS individuals carry variants in either the COL5A1 or COL5A2 genes. Mosaicism is relatively common in heritable connective tissue disorders but is rare in EDS. In cEDS, a single example of presumed gonosomal mosaicism for a COL5A1 variant has been published to date. (2) Methods: An 8-year-old girl with cEDS was analyzed by next-generation sequencing (NGS). Segregation was performed by Sanger sequencing in her unaffected parents. In the father, the mosaicism of the variant was further analyzed by targeted NGS and droplet digital PCR (ddPCR) in the blood and by Sanger sequencing in other tissues. (3) Results: The NGS analysis revealed the novel germline heterozygous COL5A1 c.1369G>T, p.(Glu457*) variant in the proband. Sanger chromatogram of the father's blood specimen suggested the presence of a low-level mosaicism for the COL5A1 variant, which was confirmed by NGS and estimated to be 4.8% by ddPCR. The mosaicism was also confirmed by Sanger sequencing in the father's saliva, hair bulbs and nails. (4) Conclusions: We described the second case of cEDS caused by paternal gonosomal mosaicism in COL5A1. Parental mosaicism could be an issue in cEDS and, therefore, considered for appropriate genetic counseling.

From late fatherhood to prenatal screening of monogenic disorders: evidence and ethical concerns

BACKGROUND

With the help of ART, an advanced parental age is not considered to be a serious obstacle for reproduction anymore. However, significant health risks for future offspring hide behind the success of reproductive medicine for the treatment of reduced fertility associated with late parenthood. Although an advanced maternal age is a well-known risk factor for poor reproductive outcomes, understanding the impact of an advanced paternal age on offspring is yet to be elucidated. De novo monogenic disorders (MDs) are highly associated with late fatherhood. MDs are one of the major sources of paediatric morbidity and mortality, causing significant socioeconomic and psychological burdens to society. Although individually rare, the combined prevalence of these disorders is as high as that of chromosomal aneuploidies, indicating the increasing need for prenatal screening. With the help of advanced reproductive technologies, families with late paternity have the option of non-invasive prenatal testing (NIPT) for multiple MDs (MD-NIPT), which has a sensitivity and specificity of almost 100%.

OBJECTIVE AND RATIONALE

The main aims of the current review were to examine the effect of late paternity on the origin and nature of MDs, to highlight the role of NIPT for the detection of a variety of paternal age-associated MDs, to describe clinical experiences and to reflect on the ethical concerns surrounding the topic of late paternity and MD-NIPT.

SEARCH METHODS

An extensive search of peer-reviewed publications (1980-2021) in English from the PubMed and Google Scholar databases was based on key words in different combinations: late paternity, paternal age, spermatogenesis, selfish spermatogonial selection, paternal age effect, de novo mutations (DNMs), MDs, NIPT, ethics of late fatherhood, prenatal testing and paternal rights.

OUTCOMES

An advanced paternal age provokes the accumulation of DNMs, which arise in continuously dividing germline cells. A subset of DNMs, owing to their effect on the rat sarcoma virus protein-mitogen-activated protein kinase signalling pathway, becomes beneficial for spermatogonia, causing selfish spermatogonial selection and outgrowth, and in some rare cases may lead to spermatocytic seminoma later in life. In the offspring, these selfish DNMs cause paternal age effect (PAE) disorders with a severe and even life-threatening phenotype. The increasing tendency for late paternity and the subsequent high risk of PAE disorders indicate an increased need for a safe and reliable detection procedure, such as MD-NIPT. The MD-NIPT approach has the capacity to provide safe screening for pregnancies at risk of PAE disorders and MDs, which constitute up to 20% of all pregnancies. The primary risks include pregnancies with a paternal age over 40 years, a previous history of an affected pregnancy/child, and/or congenital anomalies detected by routine ultrasonography. The implementation of NIPT-based screening would support the early diagnosis and management needed in cases of affected pregnancy. However, the benefits of MD-NIPT need to be balanced with the ethical challenges associated with the introduction of such an approach into routine clinical practice, namely concerns regarding reproductive autonomy, informed consent, potential disability discrimination, paternal rights and PAE-associated issues, equity and justice in accessing services, and counselling.

WIDER IMPLICATIONS

Considering the increasing parental age and risks of MDs, combined NIPT for chromosomal aneuploidies and microdeletion syndromes as well as tests for MDs might become a part of routine pregnancy management in the near future. Moreover, the ethical challenges associated with the introduction of MD-NIPT into routine clinical practice need to be carefully evaluated. Furthermore, more focus and attention should be directed towards the ethics of late paternity, paternal rights and paternal genetic guilt associated with pregnancies affected with PAE MDs.

A systematic study and literature review of parental somatic mosaicism of FBN1 pathogenic variants in Marfan syndrome

BACKGROUND

A proportion of de novo variants in patients affected by genetic disorders, particularly those with autosomal dominant (AD) inheritance, could be the consequence of somatic mosaicism in one of the progenitors. There is growing evidence that germline and somatic mosaicism are more common and play a greater role in genetic disorders than previously acknowledged. In Marfan syndrome (MFS), caused by pathogenic variants in the fibrillin-1 gene (FBN1) gene, approximately 25% of the disease-causing variants are reported as de novo. Only a few cases of parental mosaicism have been reported in MFS.

METHODS

Employing an amplicon-based deep sequencing (ADS) method, we carried out a systematic analysis of 60 parents of 30 FBN1 positive, consecutive patients with MFS with an apparently de novo pathogenic variant.

RESULTS

Out of the 60 parents studied (30 families), the majority (n=51, 85%) had a systemic score of 0, seven had a score of 1 and two a score of 2, all due to minor criteria common in the normal population. We detected two families with somatic mosaicism in one of the progenitors, with a rate of 6.6% (2/30) of apparently de novo cases.

CONCLUSIONS

The search for parental somatic mosaicism should be routinely implemented in de novo cases of MFS, to offer appropriate genetic and reproductive counselling as well as to reveal masked, isolated clinical signs of MFS in progenitors that may require specific follow-up.

Spontaneous Cervical Artery Dissection in Vascular Ehlers-Danlos Syndrome: A Cohort Study

BACKGROUND AND PURPOSE

Vascular Ehlers-Danlos syndrome is a rare inherited connective tissue disorder because of pathogenic variants in the COL3A1 gene. Arterial complications can affect all anatomic areas and about 25% involve supra-aortic trunks (SATs) but no systematic assessment of cervical artery lesions has been made. The primary objective was to determine an accurate prevalence of spontaneous SAT lesions in a large series of patients with vascular Ehlers-Danlos syndrome at diagnosis and during follow-up. Secondary objectives were to study their neurological consequences (transient ischemic attack or stroke) and the possible relationships with sex, genotype, ascertainment status.

METHODS

A retrospective review of a monocentric cohort of patients with molecularly proven vascular Ehlers-Danlos syndrome followed in a tertiary referral center from 2000 to 2017.

RESULTS

One hundred forty-four patients were analyzed, 56.9% (n=82) had SAT lesions: 64.6% females, 74.4% index-case patients. Most lesions were identified in early arterial assessment (48% at first work-up, mean age of 35.7±13.0 years). Cumulative incidence of a first identification of a SAT lesion was 41.7% at 40 years old. On the complete period of survey, 183 SAT lesions (with 132 dissections and 33 aneurysms) were identified, mainly in internal carotid arteries (56.3%) and vertebral arteries (28.9%), more rarely in patients with COL3A1 null mutations (P=0.008). Transient ischemic attack or stroke were reported in n=16 (19.5%) of the 82 patients with SAT lesions without relation with age, sex, treatment, or hypertension.

CONCLUSIONS

Cervical artery lesions are frequent and mostly asymptomatic in patients with vascular Ehlers-Danlos syndrome. Local dissections and aneurysms are the most frequent type of lesions, but transient ischemic attack or stroke seem rare.

Role of Clinical Genetic Testing in the Management of Aortopathies

PURPOSE OF REVIEW

Thoracic aortic aneurysms (TAA) have a strong heritable basis, and identification of a genetic etiology has important implications for patients with TAA and their relatives. This review provides an overview of Mendelian causes of TAA, discusses important considerations for genetic testing, and summarizes the impact a genetic diagnosis may have on a patient's medical care.

RECENT FINDINGS

Thoracic aortic disease may be non-syndromic or seen as part of a genetic syndrome, such as Marfan syndrome, Loeys-Dietz syndrome, or vascular Ehlers-Danlos syndrome. Expanded access to genetic testing has revealed the wide and overlapping phenotypic spectrum of these conditions, highlighting the need for genetic testing to establish an accurate diagnosis. Important aspects of genetic evaluation include thorough phenotyping through family history and physical examination, selection of an appropriate genetic test driven by the patient's phenotype, and careful interpretation of genetic test results. Improved understanding of the natural history of these conditions has led to tailored management recommendations, including gene-based recommendations for prophylactic surgical repair. Identification of a genetic etiology allows for careful monitoring of disease progression, informs the timing of prophylactic surgical repair, and facilitates the identification of other at-risk relatives through cascade genetic testing.

The Ehlers-Danlos syndromes

The Ehlers-Danlos syndromes (EDS) are a heterogeneous group of hereditary disorders of connective tissue, with common features including joint hypermobility, soft and hyperextensible skin, abnormal wound healing and easy bruising. Fourteen different types of EDS are recognized, of which the molecular cause is known for 13 types. These types are caused by variants in 20 different genes, the majority of which encode the fibrillar collagen types I, III and V, modifying or processing enzymes for those proteins, and enzymes that can modify glycosaminoglycan chains of proteoglycans. For the hypermobile type of EDS, the molecular underpinnings remain unknown. As connective tissue is ubiquitously distributed throughout the body, manifestations of the different types of EDS are present, to varying degrees, in virtually every organ system. This can make these disorders particularly challenging to diagnose and manage. Management consists of a care team responsible for surveillance of major and organ-specific complications (for example, arterial aneurysm and dissection), integrated physical medicine and rehabilitation. No specific medical or genetic therapies are available for any type of EDS.

Highly Sensitive Blocker Displacement Amplification and Droplet Digital PCR Reveal Low-Level Parental FOXF1 Somatic Mosaicism in Families with Alveolar Capillary Dysplasia with Misalignment of Pulmonary Veins

Detection of low-level somatic mosaicism [alternate allele fraction (AAF) ≤ 10%] in parents of affected individuals with the apparent de novo pathogenic variants enables more accurate estimate of recurrence risk. To date, only a few systematic analyses of low-level parental somatic mosaicism have been performed. Herein, highly sensitive blocker displacement amplification, droplet digital PCR, quantitative PCR, long-range PCR, and array comparative genomic hybridization were applied in families with alveolar capillary dysplasia with misalignment of pulmonary veins. We screened 18 unrelated families with the FOXF1 variant previously determined to be apparent de novo (n = 14), of unknown parental origin (n = 1), or inherited from a parent suspected to be somatic and/or germline mosaic (n = 3). We identified four (22%) families with FOXF1 parental somatic mosaic single-nucleotide variants (n = 3) and copy number variant deletion (n = 1) detected in parental blood samples and an AAF ranging between 0.03% and 19%. In one family, mosaic allele ratio in tissues originating from three germ layers ranged between <0.03% and 0.65%. Because the ratio of parental somatic mosaicism have significant implications for the recurrence risk, this study further implies the importance of a systematic screening of parental samples for low-level and very-low-level (AAF ≤ 1%) somatic mosaicism using methods that are more sensitive than those routinely applied in diagnostics.

The Genetics of Thoracic Aortic Aneurysms and Dissection: A Clinical Perspective

Thoracic aortic aneurysm and dissection (TAAD) affects many patients globally and has high mortality rates if undetected. Once thought to be solely a degenerative disease that afflicted the aorta due to high pressure and biomechanical stress, extensive investigation of the heritability and natural history of TAAD has shown a clear genetic basis for the disease. Here, we review both the cellular mechanisms and clinical manifestations of syndromic and non-syndromic TAAD. We particularly focus on genes that have been linked to dissection at diameters <5.0 cm, the current lower bound for surgical intervention. Genetic screening tests to identify patients with TAAD associated mutations that place them at high risk for dissection are also discussed.

Arrhythmogenic Right Ventricular Cardiomyopathy-Associated Desmosomal Variants Are Rarely De Novo

BACKGROUND

Arrhythmogenic right ventricular cardiomyopathy (ARVC) is associated with pathogenic/likely pathogenic (P/LP) variants in genes encoding the cardiac desmosomal proteins. Origin of these variants, including de novo mutation rate and extent of founder versus recurrent variants has implications for variant adjudication and clinical care, yet this has never been systematically investigated.

METHODS

We identified arrhythmogenic right ventricular cardiomyopathy probands who met 2010 Task Force Criteria and had undergone genotyping that included sequencing of the desmosomal genes (PKP2, DSP, DSG2, DSC2, and JUP) from 3 arrhythmogenic right ventricular cardiomyopathy registries in America and Europe. We classified the desmosomal variants, defined the contribution of unique versus nonunique (ie, not family-specific) P/LP variants, and identified the frequency and characteristics of de novo variants. Next, we haplotyped nonunique variants to determine how often they likely represent a single mutation event in a common ancestor (implied by shared haplotypes) versus multiple mutation events at the same genetic location.

RESULTS

Of 501 arrhythmogenic right ventricular cardiomyopathy probands, 322 (64.3%) carried 327 desmosomal P/LP variants. Most variants (n=247, 75.6%, in 245 patients) were identified in more than one proband and, therefore, considered nonunique. For 212/327 variants (64.8%) genetic cascade screening was performed extensively enough to identify the parental origin of the P/LP variant. Only 3 variants were de novo, 2 of which were whole gene deletions. For 24 nonunique P/LP PKP2 variants, haplotyping was conducted in 183 available families. For all 24 variants, multiple seemingly unrelated families sharing identical haplotypes were identified, suggesting that these variants originate from common founders.

CONCLUSIONS

Most desmosomal P/LP variants are inherited, nonunique, and originate from ancient founders. Two of 3 de novo variants were large deletions. These observations inform genetic testing, cascade screening, and variant adjudication.

Intestinal Perforation in Children as an Important Differential Diagnosis of Vascular Ehlers-Danlos Syndrome

Patient: Male, 6

Final Diagnosis: Colonic perforation secondary to vascular Ehlers Danlos Syndrome

Symptoms: Abdominal pain • constipation

Medication: —

Clinical Procedure: Loop colostomy followed by total colectomy and ileostomy

Specialty: Surgery