The genetic message of a sudden, unexpected death due to thoracic aortic dissection

Reviewing hereditary connective tissue disorders: Proposals of harmonic medicolegal assessments

Hereditary connective tissue disorders (HCTDs) are a heterogeneous group of inherited diseases. These disorders show genetic mutations with loss of function of primary components of connective tissue, such as collagen and elastic fibers. There are more than 200 conditions that involve hereditary connective tissue disorders, while the most known are Marfan syndrome, Osteogenesis Imperfecta, and Ehlers-Danlos syndromes. These disorders need continuous updates, multidisciplinary skills, and specific methodologic evaluations sharing many medicolegal issues. Marfan syndrome and Ehlers-Danlos syndromes show a high risk of early sudden death. As a consequence of this, postmortem genetic testing can identify novel genotype-phenotype correlations which help the clinicians to assess personalized cardiovascular screening programs among the ill subjects. Genetic testing is also essential to identify children suffering from Osteogenesis Imperfecta, especially when a physical abuse is clinically suspected. However, this is a well-known clinical problem even though there are still challenges to interpret genetic data and variants of unknown significance due to the current extensive use of new genetic/genomic techniques. Additionally, the more significant applications and complexities of genomic testing raise novel responsibilities on the clinicians, geneticists, and forensic practitioners as well, increasing potential liability and medical malpractice claims. This systematic review provides a detailed overview on how multidisciplinary skills belonging to clinicians, medicolegal consultants, radiologists, and geneticists can cooperate to manage HCTDs from autopsy or clinical findings to genetic testing. Thus, technical aspects need to be addressed to the medicolegal community since there is no consensus works or guidelines which specifically discuss these issues.

A harmful MYH11 variant detected in a family with thoracic aortic dissection and patent ductus arteriosus

Thoracic aortic dissection (TAD) is an important cause of sudden cardiac death and is characterized by high morbidity, mortality, and a poor prognosis. Patent ductus arteriosus (PDA) is a common congenital heart disease. The pathogenesis of both TAD and PDA has been reported to be related to genetic factors. The MYH11 gene, which encodes myosin heavy chain 11, has been reported in individuals with both TAD and PDA. Herein, we first detected a harmful MYH11 missense variant (c. T3728C, p. L1243P) in a TAD and PDA family. This missense variant co-segregated with the TAD/PDA phenotype in this family of four individuals, providing evidence of its harmfulness. Histopathological examinations revealed the presence of fragmented, broken, and lessened elastic fibers and the deposition of proteoglycans in the median of aortic dissection. Moreover, the immunofluorescence results showed that the labeled MYH11 protein in the tissue of the aortic dissection was weaker than that in the normal aorta. We present this familial case to stress the necessity of postmortem genetic testing in such cases among forensic practices. Identifying those culprit gene variants can direct effective genetic counseling and personalized health management in family members (especially first-degree relatives) with high-risk genotypes.

Molecular Genetic Characterization of Sudden Deaths Due to Thoracic Aortic Dissection or Rupture

BACKGROUND

Sudden deaths due to thoracic aortic dissection or ruptures (TADR) are often investigated by forensic pathologists in the United States. Up to a quarter of reported TADR result from a highly penetrant autosomal dominant single gene variant. Testing genes associated with familial TADR provides an underlying etiology for the cause of death and informs effective sudden death prevention for at-risk family members. At the New York City Office of Chief Medical Examiner (NYC-OCME), TADR cases are routinely tested by the in-house, CAP-accredited Molecular Genetics Laboratory. In this retrospective study, TADR and cardiovascular cases were reviewed to understand the burden of TADR in sudden deaths, value of molecular diagnostic testing in TADR, and genotype-phenotype correlations in a demographically diverse TADR cohort.

METHODS

Between July 2019 and June 2022, cases with in-house cardiovascular genetic testing at NYC-OCME were retrospectively reviewed. Twenty genes associated with familial TADR were analyzed using high throughput massive parallel sequencing on postmortem tissues or bloodspot cards. Variant interpretation was conducted according to ACMG/AMP guidelines.

RESULTS

A total of 1078 cases were tested for cardiovascular genetic conditions, of which 34 (3%) had TADR. Eight of those TADR cases had a pathogenic or likely pathogenic variant (P/LPV), 4 had a variant of uncertain significance (VUS), and 22 cases were negative for variants in TADR genes. The molecular diagnostic yield using the TADR subpanel was 23.5%. The genes with the greatest prevalence of P/LPV were FBN1 (6), followed by TGFBR2 (2), TGFBR1 (1), and MYLK (1). Highly penetrant P/LPV in TGFBR2, FBN1, and TGFBR1 were found in TADR individuals who died younger than 34 years old. Two P/LPV in FBN1 were secondary findings unrelated to cause of death. P/LPV in FBN1 included five truncating variants located in the N-terminal domains and one missense variant involved in the disulfide bonds of the EGF-like domain. All P/LPV in TGFBR1 and TGFBR2 were missense or in-frame deletion variants located in the protein kinase catalytic domain. Three variants were first reported in this study.

CONCLUSIONS

Molecular testing of familial TADR-associated genes is a highly effective tool to identify the genetic cause of TADR sudden deaths and benefits surviving at-risk families.

Tracking an Elusive Killer: State of the Art of Molecular-Genetic Knowledge and Laboratory Role in Diagnosis and Risk Stratification of Thoracic Aortic Aneurysm and Dissection

The main challenge in diagnosing and managing thoracic aortic aneurysm and dissection (TAA/D) is represented by the early detection of a disease that is both deadly and “elusive”, as it generally grows asymptomatically prior to rupture, leading to death in the majority of cases. Gender differences exist in aortic dissection in terms of incidence and treatment options. Efforts have been made to identify biomarkers that may help in early diagnosis and in detecting those patients at a higher risk of developing life-threatening complications. As soon as the hereditability of the TAA/D was demonstrated, several genetic factors were found to be associated with both the syndromic and non-syndromic forms of the disease, and they currently play a role in patient diagnosis/prognosis and management-guidance purposes. Likewise, circulating biomarker could represent a valuable resource in assisting the diagnosis, and several studies have attempted to identify specific molecules that may help with risk stratification outside the emergency department. Even if promising, those data lack specificity/sensitivity, and, in most cases, they need more testing before entering the “clinical arena”. This review summarizes the state of the art of the laboratory in TAA/D diagnostics, with particular reference to the current and future role of molecular-genetic testing.

Recommendations for genetic testing and counselling after sudden cardiac death: practical aspects for Swiss practice

There is a need to standardise, within a coordinated Swiss framework, the practical aspects of genetic testing and genetic counselling on possibly inherited cardiovascular disorders in relatives of a sudden cardiac death (SCD) victim. Because of the major advances in genetic investigation techniques and recent publication of international guidelines in the field of cardiology, genetics and pathology, we consider it important to summarise the current evidence and propose an optimal approach to post-mortem genetic investigation for SCD victims and their families in Switzerland. In this article, we discuss important technical, financial and medico-ethical aspects, and provide updated information on specific situations in which forensic pathologists, general practitioners and cardiologists should suspect a genetic origin of the SCD. At present, the principles of benefit, the duty to warn and the impact of genetic information for family members at risk are considered as strong justifications for post-mortem disclosure and prevail over the arguments of respect for a deceased person’s privacy and confidentiality. This paper underlines also the need to update and improve the general knowledge concerning the genetic risk of cardiovascular pathologies, the importance to perform an autopsy and post-mortem genetic testing in SCD victims, and to develop standardized post-mortem disclosure policy at national and international levels for SCD cases and relatives.

Postmortem genetic testing should be recommended in sudden cardiac death cases due to thoracic aortic dissection

BACKGROUND

Acute thoracic aortic dissections and ruptures, the main life-threatening complications of the corresponding aneurysms, are an important cause of sudden cardiac death. Despite the usefulness of the molecular diagnosis of these conditions in the clinical setting, the corresponding forensic field remains largely unexplored. The main goal of this study was to explore and validate a new massive parallel sequencing candidate gene​ assay as a diagnostic tool for acute thoracic aortic dissection autopsy cases.

MATERIALS AND METHODS

Massive parallel sequencing of 22 thoracic aortic disease candidate genes performed in 17 cases of thoracic aortic dissection using AmpliSeq and Ion Proton technologies. Genetic variants were filtered by location, type, and frequency at the Exome Aggregation Consortium and an internal database and further classified based on the American College of Medical Genetics and Genomics (ACMG) recommendations published in 2015. All prioritized results were confirmed by traditional sequencing.

RESULTS

From the total of 10 potentially pathogenic genetic variants identified in 7 out of the 17 initial samples, 2 of them were further classified as pathogenic, 2 as likely pathogenic, 1 as possibly benign, and the remaining 5 as variants of uncertain significance, reaching a molecular autopsy yield of 23%, approximately.

CONCLUSIONS

This massive parallel sequencing candidate gene approach proved useful for the molecular autopsy of aortic dissection sudden cardiac death cases and should therefore be progressively incorporated into the forensic field, being especially beneficial for the anticipated diagnosis and risk stratification of any other family member at risk of developing the same condition.

Differentiation of hemopericardium due to ruptured myocardial infarction or aortic dissection on unenhanced postmortem computed tomography

The aim of the study was to evaluate unenhanced postmortem computed tomography (PMCT) in cases of non-traumatic hemopericardium by establishing the sensitivity, specificity and accuracy of diagnostic criteria for the differentiation between aortic dissection and myocardial wall rupture due to infarction. Twenty six cases were identified as suitable for evaluation, of which ruptured aortic dissection could be identified as the underlying cause of hemopericardium in 50% of the cases, and myocardial wall rupture also in 50% of the cases. All cases underwent a PMCT and 24 of the cases also underwent one or more additional examinations: a subsequent autopsy, or a postmortem magnetic resonance (PMMR), or a PMCT angiography (PMCTA), or combinations of the above. Two radiologists evaluated the PMCT images and classified each case as "aortic dissection", "myocardial wall rupture" or "undetermined". Quantification of the pericardial blood was carried out using segmentation techniques. 17 of 26 cases were correctly identified, either as aortic dissections or myocardial ruptures, by both readers. 7 of 13 myocardial wall ruptures were identified by both readers, whereas both readers identified correctly 10 of 13 aortic dissection cases. Taking into account the responses of both readers, specificity was 100% for both causes of hemopericardium and sensitivity as well as accuracy was higher for aortic dissections than myocardial wall ruptures (72.7% and 87.5% vs 53.8% and 75% respectively). Pericardial blood volumes were constantly higher in the aortic dissection group, but a statistical significance of these differences could not be proven, since the small count of cases did not allow for statistical tests. This study showed that diagnostic criteria for the differentiation between ruptured aortic dissection and myocardial wall rupture due to infarction are highly specific and accurate.

Sudden aortic death-proposal for a comprehensive diagnostic approach in forensic and in clinical pathology practice

BACKGROUNDS

Aortic rupture or dissection as immediate cause of sudden death is encountered in forensic and clinical autopsy practice. Despite a common denominator of 'sudden aortic death' (SAD), we expect that in both settings the diagnostic workup, being either primarily legal or primarily disease related, differs substantially, which may affect the eventual diagnoses.

METHODS

We retrospectively reviewed case records of deceased persons who fitted a diagnosis of SAD in the continuous autopsy cohorts in a forensic (Suisse) and a clinical setting (The Netherlands). Clinical characteristics, data from post-mortem imaging, tissue blocks for histological analysis and results of ancillary studies were reviewed for its presence and outcome.

RESULTS

SAD was found in 7.7% in the forensic versus 2.2% in the clinical autopsies. In the forensic setting, autopsy was always combined with post-mortem imaging, showing variable outcome on detection of aortic disruption and/or pericardial bleeding. Histology of aorta was performed in 12/35 cases, mostly in the natural deaths. In the clinical setting, histology of the aorta was available in all cases, but post-mortem imaging in none. In both settings, underlying aortic disease was mostly cystic medial degeneration, atherosclerosis or a combination of both, with occasional rare unexpected diagnosis. Also in both, a genetic cause of aortic dissection was revealed in a minority (three cases).

CONCLUSION

Sudden aortic death (SAD) is more commonly encountered in a forensic than in a clinical setting. Major differences in the approach of SAD between these settings coincide with similarities in causes of death and underlying diseases. To ensure a correct diagnosis, we recommend that the investigation of SAD includes a study of the medical history, a full autopsy with histology of major organs including aorta, and storage of material for toxicological and genetic testing. Post-mortem radiological examination, useful for documentation and screening purposes, is feasible as non-invasive alternative when autopsy is not possible, but cannot substitute a full autopsy.

Perspectives on the revised Ghent criteria for the diagnosis of Marfan syndrome

Three international nosologies have been proposed for the diagnosis of Marfan syndrome (MFS): the Berlin nosology in 1988; the Ghent nosology in 1996 (Ghent-1); and the revised Ghent nosology in 2010 (Ghent-2). We reviewed the literature and discussed the challenges and concepts of diagnosing MFS in adults. Ghent-1 proposed more stringent clinical criteria, which led to the confirmation of MFS in only 32%–53% of patients formerly diagnosed with MFS according to the Berlin nosology. Conversely, both the Ghent-1 and Ghent-2 nosologies diagnosed MFS, and both yielded similar frequencies of MFS in persons with a causative FBN1 mutation (90% for Ghent-1 versus 92% for Ghent-2) and in persons not having a causative FBN1 mutation (15% versus 13%). Quality criteria for diagnostic methods include objectivity, reliability, and validity. However, the nosology-based diagnosis of MFS lacks a diagnostic reference standard and, hence, quality criteria such as sensitivity, specificity, or accuracy cannot be assessed. Medical utility of diagnosis implies congruency with the historical criteria of MFS, as well as with information about the etiology, pathogenesis, diagnostic triggers, prognostic triggers, and potential complications of MFS. In addition, social and psychological utilities of diagnostic criteria include acceptance by patients, patient organizations, clinicians and scientists, practicability, costs, and the reduction of anxiety. Since the utility of a diagnosis or exclusion of MFS is context-dependent, prioritization of utilities is a strategic decision in the process of nosology development. Screening tests for MFS should be used to identify persons with MFS. To confirm the diagnosis of MFS, Ghent-1 and Ghent-2 perform similarly, but Ghent-2 is easier to use. To maximize the utility of the diagnostic criteria of MFS, a fair and transparent process of nosology development is essential.

Aortic dissection complicated with haemothorax - an autopsy report

In a forensic setting, haemothorax is usually seen in cases of trauma. The main non-traumatic cause for haemothorax is an intrathoracic rupture of an acute aortic dissection or an aortic aneurysm that is almost always fatal. Here we present one such case of sudden natural death caused by rupture of an acute aortic dissection. The deceased was a middle-aged, unidentified male who was subjected to autopsy at the Department of Forensic Medicine, M.S. Ramaiah Medical College, after having been brought in dead to the hospital. It is a type III DeBakey dissection as it originates in the descending aorta and it is quite unusual that a rare retrograde extension was also observed.

Non-traumatic and spontaneous hemothorax in the setting of forensic medical examination: a systematic literature survey

Spontaneous hemothorax is a well-known yet seldom-reported entity in forensic literature. While trauma-related hemothorax is frequently encountered in a medicolegal setting, non-traumatic and spontaneous hemothorax are relatively uncommon entities. The wide range of causes that can trigger fatal intrathoracic bleeding include thoracic aortic dissection, followed by vascular malformations, various oncological diseases, and connective tissue abnormalities. In rare instances, extramedullary hematopoiesis, ectopic pregnancy, congenital heart defects, amyloidosis, or parasitic diseases may constitute a source of bleeding. This etiological heterogeneity may, as a result, cause diagnostic difficulties during post-mortem elucidation of hemothorax. It should be borne in mind that hemothorax after low-energy trauma does not exclusively indicate traumatic hemorrhage, hence, the non-traumatic origin of bleeding must be taken into consideration. In this paper, we present a systematic review of the relevant literature enriched by the results of our observations to investigate the etiologies and recommendations for the post-mortem diagnosis of spontaneous hemothorax in an attempt to better delineate the possible medicolegal considerations. It is important that forensic pathologist as well as clinicians are aware of the diseases that could potentially give rise to fatal hemothorax.

Aortic Dissection in the Young: A Case Report and Review of the Differential Diagnostic Considerations

Aortic dissection is a rare cause of death in young adults, which may be caused by acquired or congenital factors. We present the case of a 21-year-old man who died as a result of spontaneous aortic dissection and cardiac tamponade. At autopsy, signs of Marfan syndrome were evident both grossly and microscopically. Hodgkin lymphoma was also discovered, though was noncontributory to death. We review the causes of aortic dissection in young individuals, with a focus on the key differentiating features of predisposing inheritable connective tissue disorders. Given the implications for surviving family members, it is the obligation of the diligent forensic pathologist to be aware of these conditions, such that families may be alerted to the need for genetic counseling.

A simple clinical model to estimate the probability of Marfan syndrome

BACKGROUND

Marfan syndrome is a heritable connective tissue disease. Definitive diagnosis is complex, and requires sequencing of a large gene, FBN1.

AIM

We aimed to develop a simple model to estimate the pre-test probability of Marfan syndrome.

DESIGN

Prospective cross-sectional study.

METHODS

We applied diagnostic standards for definitive diagnosis or exclusion of Marfan syndrome in 329 consecutive persons. In 208 persons with random assignment to our derivation group, we performed multivariate logistic regression to assess 14 clinical variables for inclusion in a prediction model with derivation of score points from the estimated coefficients. We created cut-offs to classify low, moderate and high probability of Marfan syndrome. For validation, we applied the model to the remaining 121 persons.

RESULTS

We identified seven variables for inclusion in the final model, where we assigned four score points to ectopia lentis, two points to a family history of Marfan syndrome, and one point to previous thoracic aortic surgery, to pectus excavatum, to a wrist and thumb sign, to previous pneumothorax, and to skin striae. In the derivation group 12, 42 and 92% of persons with low (≤1 point), moderate (>1-3.5 points) or high pre-test probability (>3.5 points) had Marfan syndrome, compared to 12, 57 and 91%, respectively, in the validation group. Positive likelihood ratios were 13.96 and 8.54 in the high probability group of the derivation and validation group, respectively.

CONCLUSION

A simple prediction model provides evidence for Marfan syndrome. This model can be used to identify patients who require definitive diagnostic work-up.

Causes and histopathology of ascending aortic disease in children and young adults

BACKGROUND

Ascending aortic diseases (aneurysms, dissections, and stenosis) and associated aortic valve disease are rare but important causes of morbidity and mortality in children and young adults. Certain genetic causes, such as Marfan syndrome and congenital bicuspid aortic valve disease, are well known. However, other rarer genetic and nongenetic causes of aortic disease exist.

METHODS

We performed an extensive literature search to identify known causes of ascending aortic pathology in children and young adults. We catalogued both aortic pathologies and other defining systemic features of these diseases.

RESULTS

We describe 17 predominantly genetic entities that have been associated with thoracic aortic disease in this age group.

CONCLUSIONS

While extensive literature on the common causes of ascending aortic disease exists, there is a need for better histologic documentation of aortic pathology in rarer diseases.

Association of Intracranial Aneurysm and Loeys-Dietz Syndrome: Case Illustration, Management, and Literature Review

BACKGROUND AND IMPORTANCE:

Loeys-Dietz syndrome (LDS) is a newly described connective tissue disease associated with aortic aneurysms. A strong association between LDS and intracranial aneurysms has not yet been documented in the literature. We present the first detailed report of an intracranial aneurysm finding in an LDS patient.

CLINICAL PRESENTATION:

The patient is a 20-year-old female recently diagnosed with LDS and found to harbor 2 incidental intracranial aneurysms on a screening magnetic resonance angiography: a 3-mm right carotid ophthalmic aneurysm and an 8-mm partially fusiform paraclinoid carotid artery aneurysm. A standard left pterional craniotomy was performed. Intraoperative adenosine was used instead of temporary clipping because her vessels were extremely friable. After reconstruction, an intraoperative indocyanine green angiogram was obtained, confirming complete aneurysmal obliteration and internal carotid artery patency.

CONCLUSION:

This is the first detailed report of a clear association between intracranial aneurysms and LDS. An association between LDS and intracranial aneurysms, if substantiated in a larger study, has implications for aneurysm screening in this population. Such an association may shed light on mechanisms of aneurysm formation, growth, and rupture.

Postmortem genetic analysis for a sudden death case complicated with Marfan syndrome

We report here a sudden death case of a patient previously diagnosed as Marfan syndrome (MFS). The victim was dead on the wheel and the cause of death was diagnosed to be a rupture of the thoracic aorta by autopsy findings. MFS is an autosomal dominant disorder of the connective tissue and can be a cause of sudden death. Postmortem genetic analysis revealed a heterozygous p.C1307Y of the FBN1 gene, which is responsible for pathogenesis of MFS, was evident. This substitution was not found in 400 alleles from control individuals. In addition, the position 1307 is highly conserved among species. Because the position 1307 serves as part of the Cys1307-Cys1320 disulfide bond of the fibrillin-1, the p.C1307Y substitution results in loss of the intramolecular disulfide bond. The p.C1307Y substitution may be associated with the pathology of the present case, and show a higher risk for aortic rupture and subsequent sudden death.