Imaging Manifestations of Neurologic Complications in Anemia

Stretch-activated ion channel TMEM63B associates with developmental and epileptic encephalopathies and progressive neurodegeneration

By converting physical forces into electrical signals or triggering intracellular cascades, stretch-activated ion channels allow the cell to respond to osmotic and mechanical stress. Knowledge of the pathophysiological mechanisms underlying associations of stretch-activated ion channels with human disease is limited. Here, we describe 17 unrelated individuals with severe early-onset developmental and epileptic encephalopathy (DEE), intellectual disability, and severe motor and cortical visual impairment associated with progressive neurodegenerative brain changes carrying ten distinct heterozygous variants of TMEM63B, encoding for a highly conserved stretch-activated ion channel. The variants occurred de novo in 16/17 individuals for whom parental DNA was available and either missense, including the recurrent p.Val44Met in 7/17 individuals, or in-frame, all affecting conserved residues located in transmembrane regions of the protein. In 12 individuals, hematological abnormalities co-occurred, such as macrocytosis and hemolysis, requiring blood transfusions in some. We modeled six variants (p.Val44Met, p.Arg433His, p.Thr481Asn, p.Gly580Ser, p.Arg660Thr, and p.Phe697Leu), each affecting a distinct transmembrane domain of the channel, in transfected Neuro2a cells and demonstrated inward leak cation currents across the mutated channel even in isotonic conditions, while the response to hypo-osmotic challenge was impaired, as were the Ca2+ transients generated under hypo-osmotic stimulation. Ectopic expression of the p.Val44Met and p.Gly580Cys variants in Drosophila resulted in early death. TMEM63B-associated DEE represents a recognizable clinicopathological entity in which altered cation conductivity results in a severe neurological phenotype with progressive brain damage and early-onset epilepsy associated with hematological abnormalities in most individuals.

Prevalence and determinants of anemia at discharge in pediatric intensive care survivors

BACKGROUND

Restrictive transfusion practices are increasingly being followed in pediatric intensive care units (PICU); consequently, more patients are discharged anemic from PICU. Given the possible impact of anemia on long-term neurodevelopmental outcomes, we aim to describe the epidemiology of anemia at PICU discharge in a mixed (pediatric and cardiac) cohort of PICU survivors and to characterize risk factors for anemia.

STUDY DESIGN AND METHODS

We performed a retrospective cohort study in the PICU of a multidisciplinary tertiary-care university-affiliated center. All consecutive PICU survivors for whom a hemoglobin level was available at PICU discharge were included. Baseline characteristics and hemoglobin levels were extracted from an electronic medical records database.

RESULTS

From January 2013 to January 2018, 4750 patients were admitted to the PICU (97.1% survival); discharge hemoglobin levels were available for 4124 patients. Overall, 50.9% (n = 2100) were anemic at PICU discharge. Anemia at PICU discharge was also common in the cardiac surgery population (53.3%), mainly in acyanotic patients; only 24.6% of cyanotic patients were anemic according to standard definitions of anemia. Cardiac surgery patients were transfused more often and at higher hemoglobin levels than medical and non-cardiac surgery patients. Anemia at admission was the strongest predictor of anemia at discharge (odds ratios (OR): 6.51, 95% confidence interval (CI:5.40;7.85)).

DISCUSSION

Half of PICU survivors are anemic at discharge. Further studies are required to determine the course of anemia after discharge and to ascertain whether anemia is associated with adverse long-term outcomes.