Gain-of-Function Mutations in IFIH1 Cause a Spectrum of Human Disease Phenotypes Associated with Upregulated Type I Interferon Signaling

The type I interferon system is integral to human antiviral immunity. However, inappropriate stimulation or defective negative regulation of this system can lead to inflammatory disease. We sought to determine the molecular basis of genetically uncharacterized cases of the type I interferonopathy Aicardi-Goutières syndrome, and of other patients with undefined neurological and immunological phenotypes also demonstrating an upregulated type I interferon response. We found that heterozygous mutations in the cytosolic double-stranded RNA receptor gene IFIH1 (MDA5) cause a spectrum of neuro-immunological features consistently associated with an enhanced interferon state. Cellular and biochemical assays indicate that these mutations confer a gain-of-function - so that mutant IFIH1 binds RNA more avidly, leading to increased baseline and ligand-induced interferon signaling. Our results demonstrate that aberrant sensing of nucleic acids can cause immune upregulation.

Sepsis Mortality Prediction Based on Predisposition, Infection and Response

OBJECTIVE: To empirically test, based on a large multicenter, multinational database, whether a modified PIRO (predisposition, insult, response, and organ dysfunction) concept could be applied to predict mortality in patients with infection and sepsis. DESIGN: Substudy of a multicenter multinational cohort study (SAPS 3). PATIENTS: A total of 2,628 patients with signs of infection or sepsis who stayed in the ICU for >48 h. Three boxes of variables were defined, according to the PIRO concept. Box 1 (Predisposition) contained information about the patient's condition before ICU admission. Box 2 (Injury) contained information about the infection at ICU admission. Box 3 (Response) was defined as the response to the infection, expressed as a Sequential Organ Failure Assessment score after 48 h. INTERVENTIONS: None. MAIN MEASUREMENTS AND RESULTS: Most of the infections were community acquired (59.6%); 32.5% were hospital acquired. The median age of the patients was 65 (50-75) years, and 41.1% were female. About 22% (n=576) of the patients presented with infection only, 36.3% (n=953) with signs of sepsis, 23.6% (n=619) with severe sepsis, and 18.3% (n=480) with septic shock. Hospital mortality was 40.6% overall, greater in those with septic shock (52.5%) than in those with infection (34.7%). Several factors related to predisposition, infection and response were associated with hospital mortality. CONCLUSION: The proposed three-level system, by using objectively defined criteria for risk of mortality in sepsis, could be used by physicians to stratify patients at ICU admission or shortly thereafter, contributing to a better selection of management according to the risk of death.

Effects of a Shortage of Imiglucerase on Three Patients with Type I Gaucher Disease

Background: Children with Gaucher disease type I (GD1) are usually treated with enzyme replacement therapy (ERT) at a dose of 30-60U/Kg/2W. Recently, due to an acute shortage supply of imiglucerase, a reduced dose or a reduced infusion frequency was recommended. Objective: To evaluate the effects of a reduced infusion frequency of imiglucerase over 15 months of follow-up. Patients and Methods: Three patients (1M:2F) were treated with ERT since a median age of 7 years (range 5-12). Only one had bone crisis and Erlenmeyer deformations. Median duration of treatment before dose reduction was 3 years (range 1-8). ERT resulted in total regression of symptoms, normalization of hematological parameters and progressive improvement of chitotriosidase in all patients. In August 2009 infusion schedule was changed from a media 45U/Kg every two weeks to every four weeks. Results: All patients remained asymptomatic and with no major change on hematological parameters except for the patient with bone crisis who presented subnormal platelet count. All patients showed an upward trend in chitotriosidase values. Comments: Although a longer follow-up is needed, is probable that even children completely stabilized can probably not be kept on lower doses even though the reduction of frequency of the infusions represent a lower social burden.