SMDT1 variants impair EMRE-mediated mitochondrial calcium uptake in patients with muscle involvement.

Ionic calcium (Ca2+) is a key messenger in signal transduction and its mitochondrial uptake plays an important role in cell physiology. This uptake is mediated by the mitochondrial Ca2+ uniporter (MCU), which is regulated by EMRE (essential MCU regulator) encoded by the SMDT1 (single-pass membrane protein with aspartate rich tail 1) gene. This work presents the genetic, clinical and cellular characterization of two patients harbouring SMDT1 variants and presenting with muscle problems. Analysis of patient fibroblasts and complementation experiments demonstrated that these variants lead to absence of EMRE protein, induce MCU subcomplex formation and impair mitochondrial Ca2+ uptake. However, the activity of oxidative phosphorylation enzymes, mitochondrial morphology and membrane potential, as well as routine/ATP-linked respiration were not affected. We hypothesize that the muscle-related symptoms in the SMDT1 patients result from aberrant mitochondrial Ca2+ uptake.

Early MRI diagnosis of Sturge Weber Syndrome type 1 in infants.

BACKGROUND: Patients with Sturge-Weber syndrome type 1 (SWS1) have a port-wine birthmark (PWB) as cutaneous hallmark. Up to 35% of neonates with a high risk PWB develop SWS1. Clinical manifestations are severe and often progressive. Especially early onset seizures are associated with worse neurocognitive outcome. Identification of pre-symptomatic SWS1 patients is hampered because brain MRI in the first months of life does not always show the for SWS1 characteristic leptomeningeal capillary malformation (LMC). OBJECTIVES: Identification of sensitive and specific MRI predictors for early SWS1 diagnosis. METHODS: In this retrospective single centre study, we included 24 SWS1 patients and 20 controls. We studied specificity and sensitivity for SWS1 diagnosis of LMC and indirect MRI signs such as choroid plexus (CP) size and thickness, abnormal white matter signal, lobar cerebral atrophy, ischemia and cortical calcifications. RESULTS: In SWS1 patients CP thickness and CP thickness ratio on non-contrast brain MRI was significantly increased. The optimal cut-off value of 5.6 mm on the affected side corresponded with a sensitivity of 91.7% and a specificity of 100% for confirmation of SWS1 diagnosis. In 21% of children aged ≤3 months with a later confirmed SWS1 diagnosis, LMC on initial MRI could not be discerned but CP thickness ≥5.6 mm on the affected side confirmed SWS1 diagnosis. CONCLUSIONS: In this study, CP size ratio and thickness were found to be sensitive and specific signs additional to earlier described criteria to support SWS1 diagnosis in neonates and infants which need to be confirmed in other series.

The broad phenotypic spectrum of PPP2R1A-related neurodevelopmental disorders correlates with the degree of biochemical dysfunction.

PURPOSE: Neurodevelopmental disorders (NDD) caused by protein phosphatase 2A (PP2A) dysfunction have mainly been associated with de novo variants in PPP2R5D and PPP2CA, and more rarely in PPP2R1A. Here, we aimed to better understand the latter by characterizing 30 individuals with de novo and often recurrent variants in this PP2A scaffolding Aα subunit. METHODS: Most cases were identified through routine clinical diagnostics. Variants were biochemically characterized for phosphatase activity and interaction with other PP2A subunits. RESULTS: We describe 30 individuals with 16 different variants in PPP2R1A, 21 of whom had variants not previously reported. The severity of developmental delay ranged from mild learning problems to severe intellectual disability (ID) with or without epilepsy. Common features were language delay, hypotonia, and hypermobile joints. Macrocephaly was only seen in individuals without B55α subunit-binding deficit, and these patients had less severe ID and no seizures. Biochemically more disruptive variants with impaired B55α but increased striatin binding were associated with profound ID, epilepsy, corpus callosum hypoplasia, and sometimes microcephaly. CONCLUSION: We significantly expand the phenotypic spectrum of PPP2R1A-related NDD, revealing a broader clinical presentation of the patients and that the functional consequences of the variants are more diverse than previously reported.

Deleterious de novo variants of X-linked ZC4H2 in females cause a variable phenotype with neurogenic arthrogryposis multiplex congenita.

Pathogenic variants in the X-linked gene ZC4H2, which encodes a zinc-finger protein, cause an infrequently described syndromic form of arthrogryposis multiplex congenita (AMC) with central and peripheral nervous system involvement. We present genetic and detailed phenotypic information on 23 newly identified families and simplex cases that include 19 affected females from 18 families and 14 affected males from nine families. Of note, the 15 females with deleterious de novo ZC4H2 variants presented with phenotypes ranging from mild to severe, and their clinical features overlapped with those seen in affected males. By contrast, of the nine carrier females with inherited ZC4H2 missense variants that were deleterious in affected male relatives, four were symptomatic. We also compared clinical phenotypes with previously published cases of both sexes and provide an overview on 48 males and 57 females from 42 families. The spectrum of ZC4H2 defects comprises novel and recurrent mostly inherited missense variants in affected males, and de novo splicing, frameshift, nonsense, and partial ZC4H2 deletions in affected females. Pathogenicity of two newly identified missense variants was further supported by studies in zebrafish. We propose ZC4H2 as a good candidate for early genetic testing of males and females with a clinical suspicion of fetal hypo-/akinesia and/or (neurogenic) AMC.

Improved seizure control and regaining cognitive milestones after vagus nerve stimulation revision surgery in Lennox-Gastaut syndrome.

We report a child with Lennox-Gastaut syndrome with an increase in seizure frequency and loss of psychomotor skills due to a disintegrated cervical VNS lead, not detected during standard device monitoring. The lead was completely removed and replaced by a new 303 lead on the same nerve segment. After reinitiating VNS, side effects forced us to switch it off, resulting in immediate seizure recurrence. EEG recording demonstrated a non-convulsive status epilepticus that was halted by reinitiating VNS therapy. Thereafter, he remained seizure free for eight months, and regained psychomotor development.

Functional electrical stimulation of the ankle dorsiflexors during walking in spastic cerebral palsy: a systematic review.

AIM: To assess the effect of functional electrical stimulation (FES) of ankle dorsiflexors in children and adolescents with spastic cerebral palsy (CP) during walking. METHOD: A systematic review was performed using the American Academy of Cerebral Palsy and Developmental Medicine methodology and the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Six databases were searched for studies applying interventions to patients aged younger than 20 years. Outcomes were classified according to the International Classification of Functioning, Disability and Health (ICF). RESULTS: Seven hundred and eighty abstracts were found, 35 articles were fully screened, and 14 articles were used for analysis. Only five articles (three studies) were of level I to III evidence. At ICF participation and activity level, there is limited evidence for a decrease in self-reported frequency of toe-drag and falls. At ICF body structure and function level, there is clear evidence (I-III) that FES increased (active) ankle dorsiflexion angle, strength, and improved selective motor control, balance, and gait kinematics, but decreased walking speed. Adverse events include skin irritation, toleration, and acceptation issues. INTERPRETATION: There are insufficient data supporting functional gain by FES on activity and participation level. However, evidence points towards a role for FES as an alternative to orthoses in children with spastic CP. WHAT THIS PAPER ADDS: Effects of functional electrical stimulation (FES) point towards a potential role as an alternative to orthoses for patients with spastic cerebral palsy (CP). Some evidence for a decrease in self-reported frequency of toe-drag and falls with the use of FES in spastic CP. Limited evidence for improvements in activity and participation in patients with spastic CP using FES.

The quantitative effect of serum albumin, serum urea, and valproic acid on unbound phenytoin concentrations in children.

Dosing of phenytoin is difficult in children because of its variable pharmacokinetics and protein binding. Possible covariates for this protein binding have mostly been univariately investigated in small, and often adult, adult populations. We conducted a study to identify and quantify these covariates in children. We extracted data on serum phenytoin concentrations, albumin, triglycerides, urea, total bilirubin and creatinine concentrations and data on coadministration of valproic acid or carbamazepine in 186 children. Using nonlinear mixed effects modeling the effects of covariates on the unbound phenytoin fraction were investigated. Serum albumin, serum urea concentrations, and concomitant valproic acid use significantly influenced the unbound phenytoin fraction. For clinical practice, we recommend that unbound phenytoin concentrations are measured routinely. However, if this is impossible, we suggest to use our model to calculate the unbound concentration. In selected children, close treatment monitoring and dose reductions should be considered to prevent toxicity.

Etiology-specific differences in motor function after hemispherectomy.

Prediction of functional motor outcome after hemispherectomy is difficult due to the heterogeneity of motor outcomes observed. We hypothesize that this might be related to differences in plasticity during the onset of the underlying epileptogenic disorder or lesion and try to identify predictors of motor outcome after hemispherectomy. Thirty-five children with different etiologies (developmental, stable acquired or progressive) underwent functional hemispherectomy and motor function assessment before hemispherectomy and 24 months after hemispherectomy. Preoperatively, children with developmental etiologies performed better in terms of distal arm strength and hand function, but not on gross motor function tests. Postoperatively, the three etiology groups performed equally poor in muscle strength and hand function, but gross motor function improved in those with acquired and progressive etiologies. Loss of voluntary hand function and distal arm strength after surgery was associated with etiology, intact insular cortex and intact structural integrity of the ipsilesional corticospinal tract on presurgical MRI scans. In conclusion, postoperative motor function can be predicted more precisely based on etiology and on preoperative MRI. Children with developmental etiology more often lose distal arm strength and hand function and show less improvement in gross motor function, compared to those with acquired pathology.

MRI, volumetry, 1H spectroscopy, and cerebropetal blood flowmetry in childhood idiopathic anatomic megalencephaly.

PURPOSE: To evaluate cerebral abnormalities in childhood idiopathic anatomic megalencephaly (MC) by means of different magnetic resonance (MR) modalities. MATERIALS AND METHODS: MRI, volumetry, spectroscopy, and cerebropetal blood flowmetry were performed in six children with idiopathic anatomic MC, and seven volunteers. RESULTS: MRI revealed an increased ventricular system in five of six patients. A thalamic hamartoma was found in one patient and a Chiari I malformation was found in two. Volumetric analysis showed a disproportional increase of ventricular volume but normal subarachnoid cerebrospinal fluid (CSF) volume. Supratentorial volume was disproportionally increased compared to cerebellar volume. Intracranial volume correlated significantly with skull circumference. MR spectroscopy (MRS) N-acetyl aspartate/choline (NAA/Cho) peak ratios in WM were significantly higher in patients than in controls. Choline/creatine (Cho/Cr) peak ratios in WM were significantly lower in patients. Cortical gray matter (GM) MRS ratios were unaltered. Cerebropetal flow was increased in MC, possibly related to increased brain volume. CONCLUSION: This study reveals associated developmental anomalies for idiopathic anatomic MC. A relative ventriculomegaly was found, which should not be misinterpreted as true hydrocephalus. In contrast to metabolic MC, MRS showed no severe disturbances. Total intracranial volume is correlated to skull circumference and cerebropetal blood flow.