Sudden arrhythmia death syndrome in young victims: a five-year retrospective review and two-year prospective molecular autopsy study by next-generation sequencing and clinical evaluation of their first-degree relatives.

OBJECTIVE: Sudden arrhythmia death syndrome (SADS) accounts for about 30% of causes of sudden cardiac death (SCD) in young people. In Hong Kong, there are scarce data on SADS and a lack of experience in molecular autopsy. We aimed to investigate the value of molecular autopsy techniques for detecting SADS in an East Asian population. METHODS: This was a two-part study. First, we conducted a retrospective 5-year review of autopsies performed in public mortuaries on young SCD victims. Second, we conducted a prospective 2-year study combining conventional autopsy investigations, molecular autopsy, and cardiac evaluation of the first-degree relatives of SCD victims. A panel of 35 genes implicated in SADS was analysed by next-generation sequencing. RESULTS: There were 289 SCD victims included in the 5-year review. Coronary artery disease was the major cause of death (35%); 40% were structural heart diseases and 25% were unexplained. These unexplained cases could include SADS-related conditions. In the 2-year prospective study, 21 SCD victims were examined: 10% had arrhythmogenic right ventricular cardiomyopathy, 5% had hypertrophic cardiomyopathy, and 85% had negative autopsy. Genetic analysis showed 29% with positive heterozygous genetic variants; six variants were novel. One third of victims had history of syncope, and 14% had family history of SCD. More than half of the 11 first-degree relatives who underwent genetic testing carried related genetic variants, and 10% had SADS-related clinical features. CONCLUSION: This pilot feasibility study shows the value of incorporating cardiac evaluation of surviving relatives and next-generation sequencing molecular autopsy into conventional forensic investigations in diagnosing young SCD victims in East Asian populations. The interpretation of genetic variants in the context of SCD is complicated and we recommend its analysis and reporting by qualified pathologists.

Genetic Otx2 mis-localization delays critical period plasticity across brain regions.

Accumulation of non-cell autonomous Otx2 homeoprotein in postnatal mouse visual cortex (V1) has been implicated in both the onset and closure of critical period (CP) plasticity. Here, we show that a genetic point mutation in the glycosaminoglycan recognition motif of Otx2 broadly delays the maturation of pivotal parvalbumin-positive (PV+) interneurons not only in V1 but also in the primary auditory (A1) and medial prefrontal cortex (mPFC). Consequently, not only visual, but also auditory plasticity is delayed, including the experience-dependent expansion of tonotopic maps in A1 and the acquisition of acoustic preferences in mPFC, which mitigates anxious behavior. In addition, Otx2 mis-localization leads to dynamic turnover of selected perineuronal net (PNN) components well beyond the normal CP in V1 and mPFC. These findings reveal widespread actions of Otx2 signaling in the postnatal cortex controlling the maturational trajectory across modalities. Disrupted PV+ network function and deficits in PNN integrity are implicated in a variety of psychiatric illnesses, suggesting a potential global role for Otx2 function in establishing mental health.

Serotonin syndrome following overdose of a non-prescription slimming product containing sibutramine: a case report.

INTRODUCTION: Non-prescription slimming products are popular and can be easily purchased from the Internet. However, adulteration of these products with undeclared substances including prescription drugs is not uncommon. We report a case of serotonin syndrome after an overdose of a non-prescription product containing sibutramine. CASE REPORT: A 21-year-old woman presented with somnolence, sinus tachycardia, generalised increase in tone, hyper-reflexia and clonus more prominent in the lower limbs after an intentional overdose of a non-prescription slimming product obtained from the Internet. The product was later found to contain sibutramine and other substances such as animal thyroid tissues, caffeine and phenolphthalein. Quantitative analysis of patient's serum on presentation revealed a sibutramine concentration of 112 ng/mL, which far exceeded the reported peak serum concentration after a single oral dose of 15 mg (the maximum daily recommended dose). No other culpable agent was identified. The overall clinical presentation was compatible with serotonin syndrome associated with sibutramine overdose. The patient made a full recovery after supportive management. DISCUSSION AND CONCLUSION: This case highlighted the health threat posed by non-prescription slimming products sold over the Internet. Sibutramine overdose can result in serotonin syndrome, as in overdose of other serotonergic agents. Early recognition and timely supportive treatment are essential to ensure a good clinical outcome.