Investigating cardiac genetic background in sudden infant death syndrome (SIDS).

Sudden infant death syndrome (SIDS) is still the leading cause of death for newborns in developed countries. The pathophysiological mechanisms have not been fully clarified, but in some of SIDS cases variants of genes associated with inherited cardiac conditions are found. In this study, an analysis of SCD-related genes was performed to determine the prevalence of rare pathogenic (P) or likely pathogenic (LP) variants that could provide an unambiguous explanation for the fatal event. A cohort of 76 SIDS cases underwent Next-Generation Sequencing (NGS) analysis with a custom panel of SCD-related genes. Rare variants were classified according to the guidelines provided by the American College of Medical Genetics and Genomics (ACMG) and the specifications of the ClinGen association. Post-mortem genetic testing identified 50 (65.8%) carriers of at least one variant in SCD genes. 104 rare genetic variants were found, 65.4% in genes encoding structural proteins. Only 4 out of 76 cases (5.3%) hosted at least a P or LP variant found in genes with structural or structural/arrhythmogenic functions (SLC22A5, SCN5A, MYL3and TTN). 99 variants were classified as of uncertain significance (VUS). The difference in the distribution of variants between gene groups by function was not statistically significant (chi square, p = 0,219). Despite this, most of the variants concerned structural genes that were supposed to have a close interaction with ion channels, thus providing an explanation for the arrhythmic event. Segregation analysis, reclassification of VUS variants and identification of new associated genes could clarify the implications of the current findings.

Unpredicted Aberrant Splicing Products Identified in Postmortem Sudden Cardiac Death Samples.

Molecular screening for pathogenic mutations in sudden cardiac death (SCD)-related genes is common practice for SCD cases. However, test results may lead to uncertainty because of the identification of variants of unknown significance (VUS) occurring in up to 70% of total identified variants due to a lack of experimental studies. Genetic variants affecting potential splice site variants are among the most difficult to interpret. The aim of this study was to examine rare intronic variants identified in the exonic flanking sequence to meet two main objectives: first, to validate that canonical intronic variants produce aberrant splicing; second, to determine whether rare intronic variants predicted as VUS may affect the splicing product. To achieve these objectives, 28 heart samples of cases of SCD carrying rare intronic variants were studied. Samples were analyzed using 85 SCD genes in custom panel sequencing. Our results showed that rare intronic variants affecting the most canonical splice sites displayed in 100% of cases that they would affect the splicing product, possibly causing aberrant isoforms. However, 25% of these cases (1/4) showed normal splicing, contradicting the in silico results. On the contrary, in silico results predicted an effect in 0% of cases, and experimental results showed >20% (3/14) unpredicted aberrant splicing. Thus, deep intron variants are likely predicted to not have an effect, which, based on our results, might be an underestimation of their effect and, therefore, of their pathogenicity classification and family members' follow-up.

Post-mortem toxicology analysis in a young sudden cardiac death cohort.

Risk of sudden cardiac death (SCD) increases with age, and several studies have examined the impact of different drugs on cardiovascular function. However, few studies have integrated epidemiological drug consumption data and genetic background in the context of cardiac death. We performed a retrospective population-based study in forensic sudden death cases from a 9-year period in Catalonia. The young cohort included 924 cases 18-50 years old, 566 of which had a cardiac cause of death. Complete autopsy, toxicological, and histopathological studies were performed. Molecular autopsy using next-generation sequencing was performed in nearly 400 cardiac cases. Cases related with fatal acute intoxication were excluded. Drug consumption prevalence was similar between forensic cases of cardiac and non-cardiac origin (62.5% versus 69.5%), with the exception of alcohol, which was more prevalent in the cardiac group than in the non-cardiac group (23.3% versus 17.1%). Individuals in the toxicology-positive group were carriers of more rare genetic variants and were significantly younger than the toxicology-negative group. Psychopharmacological drugs were identified in 22.3% of cardiac cases, and molecular autopsy identified an association between antiepileptic drugs or caffeine and pathogenic or likely pathogenic variants in arrhythmogenic genes. Specific substances could therefore play an essential role as triggers of SCD in genetically predisposed young people.

Rare variants in genes encoding structural myocyte contribute to a thickened ventricular septum in sudden death population without ventricular alterations.

Unexpected cardiac deaths are a current challenge to healthcare systems. In adults, coronary artery disease and acquired cardiomyopathies are the most frequent causes of sudden cardiac death while in younger than 35 years old, the main cause is represented by non-ischemic diseases, usually inherited. Nowadays, around 10%-15% of unexpected deaths remain without a definite cause of decease after a complete autopsy, then classified as deaths potentially due to an inherited arrhythmia. Discrete abnormalities in some of the heart measures have been considered as potential predictors or risk factors for sudden cardiac death. However, role of non-benign genetic variants in these scattered heart alterations remains to be clarified, especially if variants are classified of ambiguous role. Clinicians usually only take into consideration pathogenic variants for decision-making. It is yet unclear what the role of VUS genetic variants in modifying the anatomical parameters of the heart. We hypothesize that some heart measures might be influenced by polygenic components as some variants may individually confer minor risk but may actually produce additive effects when combined with others. Our aim was to investigate whether carrying non-benign rare variants in genes related to inherited arrhythmias may contribute to scattered cardiac alterations in anatomical normal hearts. The study is composed by 761 samples collected from autopsies of SD suffered by adults from 18 to 50 years of age who occurred in Catalonia (Spain) in a 9-year period. Complete medico-legal autopsy was performed to determine the cause of death. Molecular autopsy was performed as part of our forensic protocol, including genes associated with inherited diseases.To evaluate the effect of genetic rare variants into hearts measures we performed a linear regression model and data were presented as regression. This study showed, for the first time, that rare variants, regardless of significance (pathogenic, probably pathogenic or uncertain significance), may contribute to interventricular septum width in the structurally normal heart. While the cohort is based on sudden death cases, further studies and case-control studies will be necessary to conclude that the genetic determinants of septal thickness contributes to sudden cardiac death. We conclude that non-benign rare variants contribute to modify scattered septum width in structural normal hearts, being a potential risk factor of arrhythmia in genetic harbors. These evidence support the current recommendation in forensic protocols of including histologic analysis of septum when inherited arrhythmogenic disease is suspicious cause of decease.

Controlling the spin-crossover behavior of the [Cr(indenyl)2] family via ligand functionalization.

In this work, a computational method to study the spin-crossover (SCO) behavior of the [Cr(n-Meindenyl)2] family was carried out. Using the TPSSh/Def2TZVP method with the GD3BJ dispersion correction scheme, we computed the thermochemistry and transition temperatures (T1/2) for all members of this family, which are in excellent agreement with the available experimental data. Moreover, the computed data allow us to build a model that describes the effect of functionalizing the indenyl ligand in different positions on the spin-state energy gap and transition temperature. Our results show that the C4 and C7 positions of the indenyl ligand have a greater effect on tuning the SCO properties of such complexes. The model quantitatively reproduces the DFT calculations, thus providing a powerful tool to analyze and predict the SCO properties in any member of the [Cr(n-Meindenyl)2] family.

Oxidative and Nitrosative Pattern in Circulating Leukocytes of Very Early/Early Hepatocellular Carcinoma Patients.

BACKGROUND/AIM: In chronic liver disease, various immune cell subsets exert pro or anti-tumour effects by releasing reactive oxygen and nitrogen species (ROS, RNS). Here, we evaluated the oxidative and nitrosative pattern in peripheral blood leukocyte subpopulations of early hepatocellular carcinoma (HCC) patients compared with HCC-free cirrhotic patients. MATERIALS AND METHODS: Venous blood samples from 18 HCC-free cirrhotic patients and 17 early stage HCC patients were collected to determine ROS, RNS and reduced glutathione levels in isolated leukocytes analyzed by flow cytometry. RESULTS: Intracellular levels of ROS and glutathione were higher in lymphocytes, monocytes, and neutrophils from HCC patients as well as mitochondrial superoxide in neutrophils and monocytes whereas intracellular levels of nitric oxide were lower in lymphocytes, monocytes, and neutrophils. CONCLUSION: Early HCC alters intracellular levels of ROS and RNS of some circulating leukocytes subsets. This finding may represent a potential area of interest concerning the development of new treatments and prognostic markers.

Omics in Zebrafish Teratogenesis.

The genome revolution represents a complete change on our view of biological systems. The quantitative determination of changes in all major molecular components of the living cells, the "omics" approach, opened whole new fields for all health sciences. Genomics, transcriptomics, proteomics, metabolomics, and others, together with appropriate prediction and modeling tools, will mark the future of developmental toxicity assessment both for wildlife and humans. This is especially true for disciplines, like teratology, which rely on studies in model organisms, as studies at lower levels of organization are difficult to implement. Rodents and frogs have been the favorite models for studying human reproductive and developmental disorders for decades. Recently, the study of the development of zebrafish embryos (ZE) is becoming a major alternative tool to adult animal testing. ZE intrinsic characteristics makes this model a unique system to analyze in vivo developmental alterations that only can be studied applying in toto approaches. Moreover, under actual legislations, ZE is considered as a replacement model (and therefore, excluded from animal welfare regulations) during the first 5 days after fertilization. Here we review the most important components of the zebrafish toolbox available for analyzing early stages of embryotoxic events that could eventually lead to teratogenesis.

Setting the light conditions for measuring root transparency for age-at-death estimation methods.

Age-at-death estimation is one of the main goals in forensic identification, being an essential parameter to determine the biological profile, narrowing the possibility of identification in cases involving missing persons and unidentified bodies. The study of dental tissues has been long considered as a proper tool for age estimation with several age estimation methods based on them. Dental age estimation methods can be divided into three categories: tooth formation and development, post-formation changes, and histological changes. While tooth formation and growth changes are important for fetal and infant consideration, when the end of dental and skeletal growth is achieved, post-formation or biochemical changes can be applied. Lamendin et al. in J Forensic Sci 37:1373-1379, (1992) developed an adult age estimation method based on root transparency and periodontal recession. The regression formula demonstrated its accuracy of use for 40 to 70-year-old individuals. Later on, Prince and Ubelaker in J Forensic Sci 47(1):107-116, (2002) evaluated the effects of ancestry and sex and incorporated root height into the equation, developing four new regression formulas for males and females of African and European ancestry. Even though root transparency is a key element in the method, the conditions for measuring this element have not been established. The aim of the present study is to set the light conditions measured in lumens that offer greater accuracy when applying the Lamendin et al. method modified by Prince and Ubelaker. The results must be also taken into account in the application of other age estimation methodologies using root transparency to estimate age-at-death.

Sudden Arrhythmic Death During Exercise: A Post-Mortem Genetic Analysis.

BACKGROUND: Sudden cardiac death is a natural and unexpected death that occurs within 1 h of the first symptom. Most sudden cardiac deaths occur during exercise, mostly as a result of myocardial infarction. After autopsy, some cases, especially in the young, are diagnosed as cardiomyopathies or remain without a conclusive cause of death. In both situations, genetic alterations may explain the arrhythmia. OBJECTIVE: Our aim was to identify a genetic predisposition to sudden cardiac death in a cohort of post-mortem cases of individuals who died during exercise, with a structurally normal heart, and were classified as arrhythmogenic death. METHODS: We analyzed a cohort of 52 post-mortem samples from individuals <50 years old who had a negative autopsy. Next-generation sequencing technology was used to screen genes associated with sudden cardiac death. RESULTS: Our cohort showed a male prevalence (12:1). Half of the deaths occurred in individuals 41-50 years of age. Running was the most common exercise activity during the fatal event, accounting for 46.15% of cases. Genetic analysis identified 83 rare variants in 37 samples (71.15% of all samples). Of all rare variants, 36.14% were classified as deleterious, being present in 53.84% of all cases. CONCLUSIONS: A comprehensive analysis of sudden cardiac death-related genes in individuals who died suddenly while exercising enabled the identification of potentially causative variants. However, many genetic variants remain of indeterminate significance, thus further work is needed before clinical translation. Nonetheless, comprehensive genetic analysis of individuals who died during exercise enables the detection of potentially causative variants and helps to identify at-risk relatives.

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Efficacy of the retreatment of hepatitis C virus infections after liver transplantation: role of an aggressive approach.

A sustained virological response (SVR) is achieved by 30% of naive liver transplantation (LT) recipients treated with pegylated interferon (PEG-IFN) and ribavirin (RBV). Almost no data are available about retreatment. The aim of this study was to assess the efficacy, tolerability, and SVR predictors of retreatment. Data were collected from 4 centers on the retreatment of prior nonresponders to standard therapy or PEG-IFN (with or without RBV) and relapsers. Seventy-nine of 301 treatment-experienced LT patients (26%), who had a median age of 59 years (range = 35-77 years) and were mostly male (72%) and infected with genotype 1 (87%), were retreated with PEG-IFN and RBV at a median of 6.9 years after LT. During the first course of therapy, 35% were treated with interferon, 49% received tacrolimus, 52% received steroids, and 49.5% were relapsers. Retreatment was started at a median of 1.9 years (range = 45 days to 8.2 years) after the end of the first course. The proportion of patients with cirrhosis increased from 10% to 37% (P < 0.001). In addition, in retreated patients, full initial RBV doses (P = 0.03), growth factors [erythropoietin (P < 0.001) and granulocyte colony-stimulating factor (P = 0.048)], and transfusions (P = 0.03) were used more frequently, and the treatment duration was longer (P = 0.03). An end-of-treatment response was achieved in 61%, whereas SVR, which was associated with improved survival, occurred in 28 (35%). The variables predicting SVR were age (P = 0.04), disease severity [fibrosis (50% with F0-F2 versus 26% with F3-4), P = 0.03; bilirubin, P = 0.006; platelet count, P = 0.03], adherence, and viral kinetics. None of the patients without an early virological response achieved SVR. There was a trend of prior relapsers achieving higher SVR rates than prior nonresponders. In conclusion, SVR, which was achieved by approximately one-third of the retreated patients, can be predicted with the same variables used for naive LT recipients (age, disease severity, adherence, and viral kinetics) and is associated with enhanced survival.

Anemia is not predictive of sustained virological response in liver transplant recipients with hepatitis C virus who are treated with pegylated interferon and ribavirin.

In the immunocompetent setting, antiviral therapy-related anemia has recently been shown to be associated with a sustained virological response (SVR). Our goal was to assess whether this is also true for liver transplantation (LT). We included 160 LT patients with recurrent hepatitis C virus (HCV) who were treated with pegylated interferon and ribavirin (RBV) between 2002 and 2010; 76% of the patients were men, the median age of the patients was 56 years (range = 33-75 years), 63% had advanced fibrosis, and 86% were infected with HCV genotype 1a or 1b. The baseline immunosuppression was tacrolimus in 56% of the patients. Mycophenolate mofetil (MMF) was used in 15%. Anemia was defined as a hemoglobin (Hb) level < 10 g/dL. Significant anemia was present when the Hb decline was >5 g/dL. Anemia and significant anemia developed in 67% and 41% of the patients, respectively. Erythropoietin was used in 60%. Factors independently associated with significant anemia included low estimated creatinine clearance [relative risk (RR) = 0.951, 95% confidence interval (CI) = 0.925-0.978, P = 0.0001], a longer time from LT to therapy (RR = 1.001, 95% CI = 1.000-1.001, P = 0.002), high baseline viremia (RR = 3.2, 95% CI = 1.3-8.1, P = 0.01), cyclosporine A (CSA)-based immunosuppression (RR: 3.472, 95% CI: 1.386-8.695; P = 0.008), and the use of MMF (RR: 5.346, 95% CI: 1.398-20.447; P = 0.014). An SVR occurred in 43% of the patients; the factors associated with an SVR included baseline variables (younger recipient age, younger donor age, infections with non-1 HCV genotypes, body mass index, and mild fibrosis) and on-treatment factors related to adherence or viral kinetics. Anemia resulted in RBV dose reductions but was not associated with the virological response at any time. In conclusion, anemia is a very frequent complication in LT patients during antiviral therapy and is associated with increased RBV dose reduction but not with an SVR. Predictors of anemia include MMF or CSA immunosuppression, high viremia, and renal insufficiency.

Genetic, endocrine, and environmental components of sex determination and differentiation in the European sea bass (Dicentrarchus labrax L.).

The European sea bass (Dicentrarchus labrax L.) is a differentiated gonochoristic marine teleost of the family Moronidae (closely related to the hermaphrodites of the family Serranidae), where many juvenile males exhibit intratesticular oocytes, suggesting a certain sexual lability. Like most fish, the sea bass does not have recognizable heterochromosomes or sex-linked markers but there are clear parental effects on the sex ratios. The data available so far indicate that the proportion of females resulting from individual crossings may range from as little as 1 to about 70%. Sex differentiation proceeds in a caudo-cranial fashion and starts when fish reach 8-9 cm standard length (usually about 200 days post-hatching, dph, under typical rearing conditions), with females differentiating first. Both forms of aromatase have been cloned in this species and their temporal expression has been studied. Brain aromatase is detectable already in the larval stages but its involvement in sex differentiation is not yet clear. The ovarian form increases after 100 dph before ovarian differentiation, with high levels in females and basal levels in males. Thus, ovarian aromatase seems to be involved in female differentiation. On the other hand, androgen receptor (AR) gene expression levels show the opposite pattern, with higher levels in males than in females. It is not yet known whether androgens are necessary for testicular differentiation or rather they are the result of it. Of the several environmental factors tested, temperature is the only one that has been shown to be able to clearly influence sex ratios. Larval and juvenile sea bass reared in captivity at high temperature usually develop as males. Recent research suggests that the high incidence of males under aquaculture conditions is due to the high water temperature used, and that the effects of temperature would be mediated by an inhibition of aromatase mRNA expression and activity in genotypic females. However, other effects of temperature mediated through alterations in developmental rates cannot be discarded. This paper reviews the current knowledge on sex determination and differentiation in the sea bass and suggests some directions for future research.