RESUMO
Defects in hydroxymethylbilane synthase (HMBS) can cause acute intermittent porphyria (AIP), an acute neurological disease. Although sequencing-based diagnosis can be definitive, â¼â of clinical HMBS variants are missense variants, and most clinically reported HMBS missense variants are designated as "variants of uncertain significance" (VUSs). Using saturation mutagenesis, en masse selection, and sequencing, we applied a multiplexed validated assay to both the erythroid-specific and ubiquitous isoforms of HMBS, obtaining confident functional impact scores for >84% of all possible amino acid substitutions. The resulting variant effect maps generally agreed with biochemical expectations and provide further evidence that HMBS can function as a monomer. Additionally, the maps implicated specific residues as having roles in active site dynamics, which was further supported by molecular dynamics simulations. Most importantly, these maps can help discriminate pathogenic from benign HMBS variants, proactively providing evidence even for yet-to-be-observed clinical missense variants.
Assuntos
Hidroximetilbilano Sintase , Porfiria Aguda Intermitente , Humanos , Hidroximetilbilano Sintase/química , Hidroximetilbilano Sintase/genética , Hidroximetilbilano Sintase/metabolismo , Mutação de Sentido Incorreto/genética , Porfiria Aguda Intermitente/diagnóstico , Porfiria Aguda Intermitente/genética , Substituição de Aminoácidos , Simulação de Dinâmica MolecularRESUMO
BACKGROUND AND IMPORTANCE: Existing data are limited for determining the medical conditions best suited for an emergency department (ED) redirection strategy in a heterogeneous, nonurgent patient population. OBJECTIVE: The aim was to establish factors associated with hospital revisits within 7 days among patients discharged or redirected by a triage team. DESIGN, SETTINGS, AND PARTICIPANTS: An observational single-center case-control study was conducted at the Tampere University Hospital ED for the full calendar year of 2019. The cases comprised unplanned hospital revisits within 7 days of being discharged or redirected by triage, while the controls were discharged or redirected but did not revisit. OUTCOME MEASURES AND ANALYSIS: The primary outcome was an unplanned hospital revisit within 7 days. A subgroup analysis was conducted for revisits leading to hospitalization. Basic demographics, comorbidities before triage, and triage visit characteristics were considered as predictive factors for the revisit. A backward stepwise conditional logistic regression analysis was performed. MAIN RESULTS: During the calendar year of 2019, there were a total of 92â 406 ED visits. Of these, 7216 (7.8%) visits were discharged or redirected by triage, and 6.5% (nâ =â 467) of all these patients revisited. Of the revisiting patients, 25% (nâ =â 117) were hospitalized. In multivariable analysis, higher age was associated with both revisitation [odds ratio (OR): 1.01, 95% confidence interval (CI): 1.00-1.02] and hospitalization (OR: 1.02, 95% CI: 1.00-1.04). Furthermore, using other visits as a reference, abdominal pain was associated with revisitation and hospitalization (OR: 3.70, 95% CI: 2.24-6.11 and OR: 5.28, 95% CI: 2.08-13.4, respectively). CONCLUSION: Higher age and abdominal pain were associated with hospital revisitation and hospitalization within 7 days among patients directly discharged or redirected by the triage team. Regardless of the triage system in use, there might be patient groups that should be evaluated more cautiously if a triage-based discharge or redirection strategy is to be considered.
RESUMO
AIM: To evaluate the significance of severe hyponatraemia presented at the emergency department (ED). METHODS: A retrospective hospital records study of all patients with plasma sodium levels of < 116 mmol/l from 2016 to 2020 in a single tertiary referral centre. RESULTS: A total of 394 visits of 363 individual severely hyponatraemic patients represented 0.08% of all ED visits. The mean age was 68 years and the male-to-female ratio was 1:1.3. The symptoms and signs were diffuse and varying, while half of the patients had neurologic symptoms. The aetiology of hyponatraemia was often multifactorial. The aetiologies varied by age, and the most common ones were the syndrome of inappropriate antidiuresis (34%), diuretic use (27%), alcohol-related (19%) and dehydration (19%). The mean sodium correction rates were 6.6, 4.9 and 3.8 mmol/l/24 h at 24, 48 and 72 h, respectively. The mean maximum correction rate over any 24-h time interval was 10.2 mmol/l. The vital signs (National Early Warning Score, NEWS) of severely hyponatraemic patients were mostly normal. All-cause mortality was 18% for 1-year follow-up. Malignancies, especially small-cell lung cancer, and end-stage liver disease caused most of the deaths. Osmotic demyelination syndrome (ODS) was diagnosed in five (1.4%) patients. CONCLUSION: Patients with severe hyponatraemia in the ED presented with non-specific complaints. The aetiology of hyponatraemia was often multifactorial and varied by age. The need for intensive care was poorly predicted by NEWS. The one-year mortality rate was 18% and the incidence of ODS 1.4% after an episode of severe hyponatraemia.
Assuntos
Hiponatremia , Humanos , Masculino , Feminino , Idoso , Hiponatremia/epidemiologia , Hiponatremia/etiologia , Hiponatremia/diagnóstico , Estudos Retrospectivos , Sódio , Diuréticos , Serviço Hospitalar de EmergênciaRESUMO
Defects in hydroxymethylbilane synthase (HMBS) can cause Acute Intermittent Porphyria (AIP), an acute neurological disease. Although sequencing-based diagnosis can be definitive, ~â of clinical HMBS variants are missense variants, and most clinically-reported HMBS missense variants are designated as "variants of uncertain significance" (VUS). Using saturation mutagenesis, en masse selection, and sequencing, we applied a multiplexed validated assay to both the erythroid-specific and ubiquitous isoforms of HMBS, obtaining confident functional impact scores for >84% of all possible amino-acid substitutions. The resulting variant effect maps generally agreed with biochemical expectation. However, the maps showed variants at the dimerization interface to be unexpectedly well tolerated, and suggested residue roles in active site dynamics that were supported by molecular dynamics simulations. Most importantly, these HMBS variant effect maps can help discriminate pathogenic from benign variants, proactively providing evidence even for yet-to-be-observed clinical missense variants.