Optimization of cloned enzyme donor immunoassay cut-offs for drugs of abuse in post-mortem whole blood

A Genome-Wide Analysis of a Sudden Cardiac Death Cohort: Identifying Novel Target Variants in the Era of Molecular Autopsy

Sudden cardiac death (SCD) is an unexpected natural death due to cardiac causes, usually happening within one hour of symptom manifestation or in individuals in good health up to 24 h before the event. Genomic screening has been increasingly applied as a useful approach to detecting the genetic variants that potentially contribute to SCD and helping the evaluation of SCD cases in the post-mortem setting. Our aim was to identify the genetic markers associated with SCD, which might enable its target screening and prevention. In this scope, a case-control analysis through the post-mortem genome-wide screening of 30 autopsy cases was performed. We identified a high number of novel genetic variants associated with SCD, of which 25 polymorphisms were consistent with a previous link to cardiovascular diseases. We ascertained that many genes have been already linked to cardiovascular system functioning and diseases and that the metabolisms most implicated in SCD are the lipid, cholesterol, arachidonic acid, and drug metabolisms, suggesting their roles as potential risk factors. Overall, the genetic variants pinpointed herein might be useful markers of SCD, but the novelty of these results requires further investigations.

The Evaluation of CYP2D6, CYP2C9, CYP2C19, and CYP2B6 Phenoconversion in Post-Mortem Casework: The Challenge of Forensic Toxicogenetics

In toxicogenetics, an integrative approach including the prediction of phenotype based on post-mortem genotyping of drug-metabolising enzymes might help explain the cause of death (CoD) and manner of death (MoD). The use of concomitant drugs, however, might lead to phenoconversion, a mismatch between the phenotype based on the genotype and the metabolic profile actually observed after phenoconversion. The aim of our study was to evaluate the phenoconversion of CYP2D6, CYP2C9, CYP2C19, and CYP2B6 drug-metabolising enzymes in a series of autopsy cases tested positive for drugs that are substrates, inducers, or inhibitors of these enzymes. Our results showed a high rate of phenoconversion for all enzymes and a statistically significant higher frequency of poor and intermediate metabolisers for CYP2D6, CYP2C9, and CYP2C19 after phenoconversion. No association was found between phenotypes and CoD or MoD, suggesting that, although phenoconversion might be useful for a forensic toxicogenetics approach, more research is needed to overcome the challenges arising from the post-mortem setting.

Sudden cardiac death related to left coronary artery anomalies including hypoplasia and anomalous origin with retro-aortic course

Congenital anomalies of the coronary arteries are a rare condition with an incidence of 0.3-1.3% in the general population. Clinically, sometimes these anomalies increase the risk of myocardial ischemia, which can present with a wide spectrum of symptoms, from angina to sudden cardiac death (SCD). This case report is about the SCD of an 8-year-old male, in apparent good health, during a football training. Although basic life support maneuvers were performed timely from bystanders and medical staff, the automated external defibrillator (AED) was not used. Autopsy revealed multiple left coronary artery (LCA) anomalies: origin from a separate ostium in the right sinus of Valsalva, slit-like shape of the ostium, acute angle take-off of the LCA from the aorta, retro-aortic course and focal coronary hypoplasia of some branches of the LCA. Microscopic examination revealed diffuse ischemic consequences at a different stage of tissue repair and mild multifocal lymphocytic infiltration. No other significant elements were detected at post-mortem examination. We discuss the forensic evaluation about the cause and the manner of death, considering also the modality of the resuscitation attempts and the claimed malpractice, as often occurs in case of sudden unexpected death in young athletes.

Development and validation of a fast UPLC-MS/MS screening method for the detection of 68 psychoactive drugs and metabolites in whole blood and application to post-mortem cases

We report a rapid and sensitive LC-MS/MS method that allows the simultaneous detection of 68 commonly prescribed antidepressants, benzodiazepines, neuroleptics, and metabolites in whole blood with a small sample volume after a rapid protein precipitation. The method was also tested on post-mortem blood from 85 forensic autopsies. Three sets of commercial serum calibrators containing a mix of prescription drugs of increasing concentration were spiked with red blood cells (RBC) to obtain 6 calibrators (3 "serum calibrators" and 3 "blood calibrators"). Curves obtained from serum calibrators and from blood calibrators were compared using a Spearman correlation test and by analyzing slopes and intercepts, to assess if the points from six calibrators could be plotted together in a single calibration model. The validation plan included interference studies, calibration model, carry-over, bias, within-run and between-run precision, limit of detection (LOD), limit of quantification (LOQ), matrix effect and dilution integrity. Four deuterated Internal Standards (Nordiazepam-D5, Citalopram-D6, Ketamine-D4 and Amphetamine-D5) and two different dilutions were assessed. Analyses were performed using an Acquity UPLC® System coupled with triple quadrupole detector Xevo TQD®. The degree of agreement with a previously validated method was calculated on whole blood samples of 85 post-mortem cases, by performing a Spearman correlation test with a Bland-Altman plot. Percentage error between the two methods was evaluated. Slopes and intercepts of curves obtained from serum calibrators and from blood calibrators showed a good correlation, and the calibration model was built plotting all points together. No interferences were found. The calibration curve appeared to provide a better fit of the data using an unweighted linear model. Negligible carry-over was observed, and very good linearity, precision, bias, matrix effect and dilution integrity were achieved. The LOD and the LOQ were at the lower limits of the therapeutic range for the tested drugs. In a series of 85 forensic cases, 11 antidepressants, 11 benzodiazepines and 8 neuroleptics were detected. For all analytes, a very good agreement between the new method and the validated method was demonstrated. The innovation of our method consists in the use of commercial calibrators, readily available to most forensic toxicology laboratories, for the validation of a fast, inexpensive, wide-panel LC-MS/MS method that can be used as a reliable and accurate screening for psychotropic drug in postmortem samples. As observed in the implementation on real cases, this method could be profitably applied in forensic cases.

Determination of multiple drugs of abuse in human urine using dispersive liquid–liquid microextraction and capillary electrophoresis with PDA detection

A new method was developed for pre-concentration and determination of multiple drugs of abuse in human urine using dispersive liquid–liquid microextraction (DLLME) and capillary electrophoresis (CE) with photodiode array detection. The method was based on the formation of tiny droplets of an organic extractant in the prepared sample solution using water-immiscible organic solvent (chloroform) dissolved in water-miscible organic dispersive solvent (isopropyl alcohol). The organic phase, which extracted eight drugs of abuse from the prepared urine solution, was separated by centrifugation. The sedimented phase was transferred into a small volume CE auto-sampler vial with 10 µL of 1% HCl methanol solution and evaporated to dryness. The residue was reconstituted in lidocaine hydrochloride (internal standard) aqueous solution and introduced by electrokinetic injection into CE. Under the optimum conditions, acceptable linear relationship was observed in the range of 3.0–500 ng/mL with the correlation coefficient (r) of 0.9982–0.9994 for spiked urine samples. The limit of detection (LOD) (S/N = 3) was estimated to be 1.0 ng/mL. A recovery of 75.7%–90.6% was obtained for spiked samples. The mean relative error (MRE) was within ±7.0% and the relative standard deviation (RSD) was less than 6.9%. The proposed DLLME-CE procedure offers an alternative analytical approach for the sensitive detection of drugs of abuse in real urine samples.

Key points

The dispersive liquid-liquid microextraction (DLLME) was involved for the determination of drugs in urine with capillary electrophoresis with photodiode array detection (CE-PDA).

Good linearity, sensitivity, recovery and precision were achieved.

The proposed method was eco-friendly with microliter scale solvent consumption.

Sudden Unexpected Death after a mild trauma: The complex forensic interpretation of cardiac and genetic findings

A 55-year-old man affected by a psychotic disorder suddenly died during a quarrel with his father. The autopsy excluded traumatic causes of death, and the cardiac examination identified a severe cardiomegaly with biventricular dilatation of very likely multifactorial origin. Toxicological and pharmacogenetic analyses excluded a fatal intoxication and identified the presence of the antipsychotic drug fluphenazine in the therapeutic range in a normal metabolizer. The screening for genetic variations highlighted a novel heterozygous single-nucleotide variant in the exon 36: c 0.4750C>A (p.Pro1584Thr) of the Ryanodine Receptor Type 2 (RYR2) gene. The mutation detected can be classified as Likely Pathogenic according to the American College of Medical Genetics and Genomics (ACMG) criteria. RYR2 variation has been associated to catecholaminergic polymorphic ventricular tachycardia (CPVT), a disease currently recognized as one of the most malignant cardiac channelopathies, expressed mostly in young patients, normally in the absence of structural heart disease. The victim late middle age, compared to juvenile onset of CPVT reported in literature, his clinical history, his structurally altered heart, circumstances at death and the absence of phenotype-related variations of dilated cardiomyopathy genes, suggested that the fatal arrhythmia could have been caused by an acquired form of dilated cardiopathy/cardiomyopathy. However, the contribution of the genetic variant to death cannot be completely ruled out, since the significance of a VUS or of a novel variant depends on the data available at the time of investigation, and should be periodically evaluated. We discuss the contribution of the structural alteration and of the variant detected, as well as the role of the molecular autopsy in forensic examination, which can make a significant contribution for inferring both cause and manner of death.

Importance of dashboard camera (Dash Cam) analysis in fatal vehicle-pedestrian crash reconstruction

The reconstruction of dynamic of traffic injuries remains a challenge in forensic pathology and is often based on circumstantial data. Dash Cams are digital video recorders which can be located inside a vehicle and continuously record the view through the windscreen, thus providing objective evidence. Here we present the case of a traffic crash in which a pedestrian was hit by an articulated lorry. The analysis of a video recorded from a Dash Cam retrieved inside the vehicle during the death scene investigation (DSI) was crucial in the reconstruction of the manner of death. Indeed, the death, which was initially assumed to be accidental, was finally deemed as a suicide on the basis of the video recording, which showed an intentional and sudden rush of the victim to the middle of the roadway. Advantages and disadvantages of the use of Dash Cams will be discussed, focusing on the profound differences in the related national and international regulations. Based on the present case, in traffic crashes, the search for Dash Cams during the DSI may be recommended and the video recordings should be analyzed in the setting of a multidisciplinary and multimodal evaluation of the case, for a proper reconstruction of the facts.

Deaths related to nitrogen inhalation: Analytical challenges

Dinitrogen (N₂) has been increasingly connected to suicidal deaths. The analysis of N₂ in post-mortem cases still represents a major challenge in forensic toxicology and circumstantial data has so far played a major role for the determination of the cause of death. In this paper, after presenting a review of cases of N₂ intoxication described in forensic literature, we report the application of two approaches in order to quantify an excess of N₂ in post-mortem whole blood collected from a case of suicide by nitrogen inhalation. N₂ analyses were performed by GC-MS on the suicidal case and on controls taken from 10 autopsy cases with similar PMI (5 traumatic deaths and 5 deaths by asphyxia). The percentage of N₂ was estimated by building a five-point N₂ peak area calibration curve (0, 15.6 %, 62.4 % 78.1 %, 100 %) and through an external QC, assessing linearity, accuracy and precision, LLOQ, specificity and stability of N₂ in the sample vial. Percentage of N₂ of the case was significantly higher than the post-mortem controls (p<0.05). The N₂/O₂ ratio of the case and controls was also calculated as an additional indicator, and was significantly higher in the case (p<0.05). The strengths and the limitation of both methods are reported in the paper. Toxicological confirmation for N₂ are rarely performed when the cause of death is evident, probably due to the lack of validated methods and the complexity of the interpretation of N₂ concentration in biological fluids. The presented methods can be rapidly and profitably applied with instrumentation normally available in forensic laboratories.