Molecular screening of selected long QT syndrome (LQTS) mutations in 165 consecutive bodies found in water

Wilderness Medical Society Clinical Practice Guidelines for the Treatment and Prevention of Drowning: 2024 Update

The Wilderness Medical Society convened a panel to review available evidence supporting practices for acute management of drowning in out-of-hospital and emergency care settings. Literature about definitions and terminology, epidemiology, rescue, resuscitation, acute clinical management, disposition, and drowning prevention was reviewed. The panel graded available evidence supporting practices according to the American College of Chest Physicians criteria and then made recommendations based on that evidence. Recommendations were based on the panel's collective clinical experience and judgment when published evidence was lacking. This is the second update to the original practice guidelines published in 2016 and updated in 2019.

Wilderness Medical Society Clinical Practice Guidelines for the Treatment and Prevention of Drowning: 2019 Update

The Wilderness Medical Society convened a panel to review available evidence supporting practices for acute management and treatment of drowning in out-of-hospital and emergency medical care settings. Literature about definitions and terminology, epidemiology, rescue, resuscitation, acute clinical management, disposition, and drowning prevention was reviewed. The panel graded available evidence supporting practices according to the American College of Chest Physicians criteria and then made recommendations based on that evidence. Recommendations were based on the panel's collective clinical experience and judgment when published evidence was lacking. This is the first update to the original practice guidelines published in 2016.

Wilderness Medical Society Practice Guidelines for the Prevention and Treatment of Drowning

The Wilderness Medical Society convened a panel to review available evidence supporting practices for the prevention and acute management of drowning in out-of-hospital and emergency medical care settings. Literature about definition and terminology, epidemiology, rescue, resuscitation, acute clinical management, disposition, and drowning prevention was reviewed. The panel graded evidence supporting practices according to the American College of Chest Physicians criteria, then made recommendations based on that evidence. Recommendations were based on the panel's collective clinical experience and judgment when published evidence was lacking.

The Forensic Pathology of Drowning and Pulmonary Overexpansion Injury

Drowning deaths are commonly seen in most forensic pathology practices. Experienced forensic pathologists perform autopsies and assign a cause and manner of death in such cases as a matter of routine. Deaths due to pulmonary overexpansion injury and subsequent air embolism are far less common and typically involve individuals who have been breathing compressed gas at depth, generally SCUBA (self-contained underwater breathing apparatus) divers. This review outlines the pathophysiological basis of these two forensic pulmonary issues and recommends an approach to performing and interpreting the results of a forensic autopsy when faced with such cases.

Unexplained drownings and the cardiac channelopathies: a molecular autopsy series

OBJECTIVE

To determine the prevalence and spectrum of mutations associated with long QT syndrome (LQTS) and catecholaminergic polymorphic ventricular tachycardia (CPVT) in a seemingly unexplained drowning cohort.

PATIENTS AND METHODS

From September 1, 1998, through October 31, 2010, 35 unexplained drowning victims (23 male and 12 female; mean ± SD age, 17±12 years [range, 4-69 years]) were referred for a cardiac channel molecular autopsy. Of these, 28 (20 male and 8 female) drowned while swimming, and 7 (3 male and 4 female) were bathtub submersions. Polymerase chain reaction, denaturing high-performance liquid chromatography, and DNA sequencing were used for a comprehensive mutational analysis of the 3 major LQTS-susceptibility genes (KCNQ1, KCNH2, and SCN5A), and a targeted analysis of the CPVT1-associated, RYR2-encoded cardiac ryanodine receptor was conducted.

RESULTS

Of the 28 victims of swimming-related drowning, 8 (28.6%) were mutation positive, including 2 with KCNQ1 mutations (L273F, AAPdel71-73 plus V524G) and 6 with RYR2 mutations (R414C, I419F, R1013Q, V2321A, R2401H, and V2475F). None of the bathtub victims were mutation positive. Of the 28 victims who drowned while swimming, women were more likely to be mutation positive than men (5/8 [62.5%] vs 3/20 [15%]; P=.02). Although none of the mutation-positive, swimming-related drowning victims had a premortem diagnosis of LQTS or CPVT, a family history of cardiac arrest, family history of prior drowning, or QT prolongation was present in 50%.

CONCLUSION

Nearly 30% of the victims of swimming-related drowning hosted a cardiac channel mutation. Genetic testing should be considered in the postmortem evaluation of an unexplained drowning, especially if a positive personal or family history is elicited.

Pharmacogenetics in medico-legal context

Medico-legal autopsy is the primary method in determining the cause and manner of death when the death is suspected to be unnatural. In some of these autopsies, the death remains ambiguous, even after a complete autopsy including histological investigation and toxicological screenings. In cases where there are no morphological abnormalities, medico-legal genetics may offer additional means to provide knowledge of possible genetic mutations, which may have initiated the process or predisposed the individual to stress risk conditions leading to death. One class of ambiguous deaths consists of drug-related deaths where the interpretation of the toxicological results are not clear. In such situations post mortem genotyping and the analysis of metabolite rations may provide an insight to the findings. A few cases demonstrating the potential strength of pharmacogenetics in medico-legal context has been published. However, there is a paramount need for serious scientific studies before the field of post mortem pharmacogenetics can be utilized in routine medico-legal analyses casework and brought routinely into courtroom.

Strategy for clinical evaluation and screening of sudden cardiac death relatives

Sudden cardiac death (SCD) may be the first and final manifestation of several heart diseases. In the young, SCD is often caused by a hereditary cardiac disease. As the most frequently seen inherited cardiac diseases have an autosomal-dominant pattern of inheritance, half of the first-degree relatives are at risk of having or developing the same disease. Therefore, screening of these high-risk relatives is a rational approach to reduce the incidence of SCD. To offer family screening and counseling, the cause of death should be carefully established. Autopsy is only performed in a limited number of cases. We advocate for systematic autopsies in SCD, because positive findings are crucial for choosing the optimal screening program for the relatives. A negative autopsy makes identification of at-risk population difficult. However, this finding also provides clues to the cardiologist, because a limited number of inherited cardiac diseases associated with SCD are without any structural changes. In other cases, the autopsy may reveal noncardiac causes of death, which is also important for reassuring the relatives. However, in cases with no autopsy or negative findings, thorough clinical examinations and selective genetic screening of relatives may identify a likely diagnosis in more than 50% of affected families. There is a need for consensus regarding routine evaluation of SCD cases and the ethical and legal framework related to postmortem testing. We propose an algorithm that narrows the diagnostic possibilities in apparently healthy relatives of young SCD victims. Molecular autopsy may play an important role.

The magnitude of sudden cardiac death in the young: a death certificate-based review in England and Wales

AIMS

In the UK, the true impact of cardiac and sudden death in the young (<or=35 years) is speculative. The authors critically appraised the office of national statistics (ONS) data for causes of death in the 1-34 years age group in England and Wales in an attempt to present an estimate of the incidence of such deaths and their underlying causes.

METHODS AND RESULTS

The investigators analysed the ONS mortality data for 2002-2005, inclusive. International classification of diseases-10 codes representing possible cardiac deaths were selected and divided into four classes; A1: definite cardiac deaths with no structural heart disease identified at post-mortem, A2: definite cardiac deaths with structural heart disease identified at post-mortem, A3: definite cardiac deaths with indeterminate cause, and B: possible cardiac deaths. Analysis of the data revealed an average of 419 (SD 16.5) definite cardiac deaths per annum (Class A1 + A2 + A3) equating to 1.8 per 100,000 per year (SD 0.08) or 8 deaths/week. There were also 433 (SD 6.2) deaths per year in class B which comprised primarily of deaths from drowning and epileptic seizures. The most prevalent causes were ischaemic heart disease (33.5%), cardiomyopathies (27%), sudden arrhythmic death syndrome (14%), myocarditis (11%), valvular heart disease (5%), and hypertensive cardiomyopathy (2%).

CONCLUSION

Our findings suggest that the number of cardiac and sudden deaths in the young identified is sufficiently high to command attention even without the inclusion of potential misclassifications (Class B). Awareness of such deaths among primary-care physicians, pathologists, and coroners should be raised to ensure that those at risk are identified and further tragedies are avoided.

Changing times: DNA resequencing and the “nearly normal autopsy”

No matter how meticulous the autopsy, non-traumatic deaths in the young go unexplained from 5-10% of the time. The percentage is higher in children and young adults. Advances in molecular biology and DNA technology now make it possible to explain many of those deaths. This development is not without irony. At the same time that many clinicians are expressing frustration about the lack of tangible gains provided by the Human Genome Project [Greenhalgh T. The Human Genome Project. J R Soc Med. Dec 2005;98(12):545], and pathologists are wondering about the viability of their field, DNA technology is about to reshape the field of forensic pathology. Emerging evidence suggests that the underlying cause of death in many is genetic, and that both the heart and liver abnormalities can both play a role. The problem is that death from a wide variety of genetic defects may leave no histological markers. The ability to identify these "invisible diseases" with postmortem genetic testing has become a reality far more quickly than anyone had ever imagined. The US Food and Drug Administration is about to place "black box" warnings on warfarin advising doctors screen potential recipients for the ability to metabolize that drug and the American Heart Association has recently editorialized that because of genetic-induced variations in electrical conduction that all newborns should have a screening electrocardiogram before they leave the hospital. The introduction of large-scale genetic screening will have an enormous effect on the practice of forensic pathology, far beyond anything seen in our lifetimes. It will also change the practice of medicine as we know it. This paper reviews the current status of the problem.

Pathogenesis of unexplained drowning: new insights from a molecular autopsy

OBJECTIVE

To perform a molecular autopsy involving the RyR2-encoded cardiac ryanodine receptor/calcium release channel to determine whether mutations responsible for catecholaminergic polymorphic ventricular tachycardia (CPVT) represent a novel pathogenic basis for unexplained drownings.

METHODS

A cardiac channel molecular autopsy was performed on 2 individuals who died of unexplained drowning and whose cases were referred to the Sudden Death Genomics Laboratory at the Mayo Clinic in Rochester, Minn. Comprehensive mutational analysis of all 60 protein-encoded exons of the 5 long QT syndrome-causing cardiac channel genes and a targeted analysis of 18 RyR2 exons known to host RyR2-mediated CPVT-causing mutations (CPVT1) was performed using polymerase chain reaction, denaturing high-performance liquid chromatography, and DNA sequencing.

RESULTS

Both individuals harbored novel mutations in RyR2. Postmortem mutational analysis revealed a familial missense mutation in exon 14, R414C, in a 16-year-old girl. A 9-year-old boy possessed a sporadic missense mutation in exon 49, V2475F. Both amino acid positions involve highly conserved residues that localize to critical functional domains in the calcium release channel. Neither substitution was present in 1000 reference alleles.

CONCLUSIONS

This molecular autopsy study provides proof of principle that RyR2 mutations can underlie some unexplained drownings. A population-based genetic epidemiology study that involves molecular autopsies of individuals who die of unexplained drowning is needed to determine the prevalence and spectrum of KCNQ1 and now RyR2 mutations as potential pathogenic mechanisms for drowning.

What Is the Incidence and Significance of “Dry-Lungs” in Bodies Found in Water?

BACKGROUND

Drowning without aspiration of liquid, generally attributed to death from asphyxia while submerged and in laryngospasm, has been reported to occur in approximately 10% to 15% of drowning victims.

OBJECTIVES

The occurrence of "dry-drowning" recently has been questioned and the hypothesis developed that "dry-lungs" in bodies found dead in the water could conceal more natural deaths than previously recognized.

METHODS

Based on 578 selected adult victims who presumably drowned, we analyzed the correlation between the cases with a low combined lung/pleura liquid weight (< 1000 g and < 750 g) and a wide set of individual, circumstantial, and postmortem (PM) variables, using multivariate logistic regression analysis. Victims with lung weight < 1000 g were screened for long-QT syndrome (LQTS) founder mutations in KCNQ1 and KCNH2 genes.

RESULTS

Of the 578 victims, 120 (20.7%) had a lung weight of < 1000 g, and 22 of these (3.8%) of < 750 g. Multivariate analysis showed a significant correlation for women (P < 0.001), for women aged 65 years or older (P < 0.001), and for men with prolonged PM submersion time (P < 0.001). "Normal" lungs were found in only 8 (1.4%) victims. Low-weight (< 1000 g), overdistended lungs with no sign of liquid penetration were seen in 11 (1.9%). No LQTS founder mutations were detected.

CONCLUSIONS

The actual incidence of death of persons found in water who have normal lungs or do not have penetration of liquid into their airways, based on our study, is much lower (below 2%) than currently assumed.

Sudden cardiac death in hereditary hemochromatosis: an underestimated cause of death?

Hereditary hemochromatosis (HH) is a frequent autosomal recessive disease which causes iron-overload of various organs. Of all northern European affected individuals, 90-95% show 1 of 3 known point mutations in the HFE gene. Symptoms and organs involved can vary considerably: Only a small fraction of the 200,000-400,000 persons affected in Germany develop the classical picture of liver cirrhosis and/or pancreatic fibrosis. Nevertheless, the life expectancy of persons with moderate or even subclinical symptoms is reduced, in many cases due to myocardial damage leading to cardiomyopathy with greatly increased risk of sudden cardiac death. Although the high prevalence of HH suggests that sudden cardiac death due to cardiac HH is a relatively common cause of death, the forensic literature lacks such reports. We present the case of sudden cardiac death in a young man with histological findings of massive cardial hemochromatosis which is characterized by the fact that none of the three known mutations for HH were found. This case demonstrates that genetic screening alone might not be sufficient to identify all persons at risk to developing HH.