De novo variants in EMC1 lead to neurodevelopmental delay and cerebellar degeneration and affect glial function in Drosophila.

BACKGROUND: The endoplasmic reticulum (ER)-membrane protein complex (EMC) is a multi-protein transmembrane complex composed of 10 subunits that functions as a membrane-protein chaperone. Variants in EMC1 lead to neurodevelopmental delay and cerebellar degeneration. Multiple families with biallelic variants have been published, yet to date, only a single report of a monoallelic variant has been described, and functional evidence is sparse. METHODS: Exome sequencing was used to investigate the genetic cause underlying severe developmental delay in three unrelated children. EMC1 variants were modeled in Drosophila, using loss-of-function (LoF) and overexpression studies. Glial-specific and neuronal-specific assays were used to determine whether the dysfunction was specific to one cell type. RESULTS: Exome sequencing identified de novo variants in EMC1 in three individuals affected by global developmental delay, hypotonia, seizures, visual impairment and cerebellar atrophy. All variants were located at Pro582 or Pro584. Drosophila studies indicated that imbalance of EMC1-either overexpression or knockdown-results in pupal lethality and suggest that the tested homologous variants are LoF alleles. In addition, glia-specific gene dosage, overexpression or knockdown, of EMC1 led to lethality, whereas neuron-specific alterations were tolerated. DISCUSSION: We establish de novo monoallelic EMC1 variants as causative of a neurological disease trait by providing functional evidence in a Drosophila model. The identified variants failed to rescue the lethality of a null allele. Variations in dosage of the wild-type EMC1, specifically in glia, lead to pupal lethality, which we hypothesize results from the altered stoichiometry of the multi-subunit protein complex EMC.

Aberrant regulation of epigenetic modifiers contributes to the pathogenesis in patients with selenoprotein N-related myopathies.

Congenital myopathies are early onset, slowly progressive neuromuscular disorders of variable severity. They are genetically and phenotypically heterogeneous and caused by pathogenic variants in several genes. Multi-minicore Disease, one of the more common congenital myopathies, is frequently caused by recessive variants in either SELENON, encoding the endoplasmic reticulum glycoprotein selenoprotein N or RYR1, encoding a protein involved in calcium homeostasis and excitation-contraction coupling. The mechanism by which recessive SELENON variants cause Multiminicore disease (MmD) is unclear. Here, we extensively investigated muscle physiological, biochemical and epigenetic modifications, including DNA methylation, histone modification, and noncoding RNA expression, to understand the pathomechanism of MmD. We identified biochemical changes that are common in patients harboring recessive RYR1 and SELENON variants, including depletion of transcripts encoding proteins involved in skeletal muscle calcium homeostasis, increased levels of Class II histone deacetylases (HDACs) and DNA methyltransferases. CpG methylation analysis of genomic DNA of patients with RYR1 and SELENON variants identified >3,500 common aberrantly methylated genes, many of which are involved in calcium signaling. These results provide the proof of concept for the potential use of drugs targeting HDACs and DNA methyltransferases to treat patients with specific forms of congenital myopathies.

Absent Thalami Caused by a Homozygous EARS2 Mutation: Expanding Disease Spectrum of LTBL.

Leukoencephalopathy with thalamus and brainstem involvement and high lactate (LTBL) is caused by autosomal recessive EARS2 mutations. Onset is most often in infancy, but in severe cases in the neonatal period. Patients typically have magnetic resonance imaging (MRI) signal abnormalities involving the thalamus, brainstem, and deep cerebral white matter. Most signal abnormalities resolve, but in severe cases at the expense of tissue loss. Here, we report a patient with an encephalopathy of antenatal onset. His early MRI at 8 months of age showed signal abnormalities in the deep cerebral white matter that improved over time. The thalami were absent with the configuration of a developmental anomaly, without evidence of a lesion. We hypothesized that this was a case of LTBL in which the thalamic damage occurred antenatally and was incorporated in the normal brain development. The diagnosis was confirmed by a novel homozygous EARS2 mutation. Our case adds to the phenotypic and genetic spectrum of LTBL.

Mutations in RARS cause hypomyelination.

Hypomyelinating disorders of the central nervous system are still a diagnostic challenge, as many patients remain without genetic diagnosis. Using magnetic resonance imaging (MRI) pattern recognition and whole exome sequencing, we could ascertain compound heterozygous mutations in RARS in 4 patients with hypomyelination. Clinical features included severe spasticity and nystagmus. RARS encodes the cytoplasmic arginyl-tRNA synthetase, an enzyme essential for RNA translation. This protein is among the subunits of the multisynthetase complex, which emerges as a key player in myelination.

A novel defect of peroxisome division due to a homozygous non-sense mutation in the PEX11ß gene.

BACKGROUND: Peroxisomes are organelles that proliferate continuously and play an indispensable role in human metabolism. Consequently, peroxisomal gene defects can cause multiple, often severe disorders, including the peroxisome biogenesis disorders. Currently, 13 different PEX proteins have been implicated in various stages of peroxisome assembly and protein import. Defects in any of these proteins result in a peroxisome biogenesis disorder. The authors present here a novel genetic defect specifically affecting the division of peroxisomes. METHODS: The authors have studied biochemical and microscopical peroxisomal parameters in cultured patient fibroblasts, sequenced candidate PEX genes and determined the consequence of the identified PEX11ß gene defect on peroxisome biogenesis in patient fibroblasts at different temperatures. RESULTS: The patient presented with congenital cataracts, mild intellectual disability, progressive hearing loss, sensory nerve involvement, gastrointestinal problems and recurrent migraine-like episodes. Although microscopical investigations of patient fibroblasts indicated a clear defect in peroxisome division, all biochemical parameters commonly used for diagnosing peroxisomal disorders were normal. After excluding mutations in all PEX genes previously implicated in peroxisome biogenesis disorders, it was found that the defect was caused by a homozygous non-sense mutation in the PEX11ß gene. The peroxisome division defect was exacerbated when the patient's fibroblasts were cultured at 40°C, which correlated with a marked decrease in the expression of PEX11γ. CONCLUSIONS: This novel isolated defect in peroxisome division expands the clinical and genetic spectrum of peroxisomal disorders and indicates that peroxisomal defects exist, which cannot be diagnosed by standard laboratory investigations.

Phenotypic expansion of EGP5-related Vici syndrome: 15 Dutch patients carrying a founder variant.

Vici syndrome (OMIM 242840) is a very rare autosomal recessive multisystem disorder first described in 1988. In 2013, bi-allelic loss-of-function mutations in EPG5 were reported to cause Vici syndrome. Five principal diagnostic features of Vici syndrome have been proposed: agenesis of the corpus callosum, cataracts, cardiomyopathy, hypopigmentation, and combined immunodeficiency. We identified 15 patients carrying a homozygous founder missense variant in EPG5 who all exhibit a less severe clinical phenotype than classic Vici syndrome. All 15 show typical brain abnormalities on MRI. The homozygous founder variant in EPG5 they carry results in a shorter in-frame transcript and truncated, but likely still residual, EPG5 protein. We speculate that the residual EPG5 protein explains their attenuated phenotype, which is consistent with two previous observations that low expression of EPG5 can lead to an attenuated Vici syndrome phenotype. We propose renaming this condition EPG5-related neurodevelopmental disorder to emphasize the clinical variability of patients with bi-allelic mutations in EPG5.

Prevalence of Bladder and Bowel Dysfunction in Duchenne Muscular Dystrophy Using the Childhood Bladder and Bowel Dysfunction Questionnaire.

INTRODUCTION: Lower urinary tract symptoms (LUTS) and gastrointestinal (GI) problems are common in Duchenne muscular dystrophy (DMD), but not systematically assessed in regular care. We aimed to determine the prevalence of bladder and bowel dysfunction (BBD) in DMD patients compared with healthy controls (HC). METHODS: The Childhood Bladder and Bowel Dysfunction Questionnaire (CBBDQ) based on the International Rome III criteria and the International Children's Continence Society was filled out by 57 DMD patients and 56 HC. Additionally, possible associations of BBD with, for example, medication use or quality of life were evaluated in an additional questionnaire developed by experts. RESULTS: In 74% of patients versus 56% of HC ≥ 1 LUTS (n.s.) were reported, 68% of patients versus 39% of HC reported ≥1 bowel symptom (p = 0.002) and 53% of patients versus 30% of HC reported combined LUTS and bowel symptoms (p = 0.019). A negative impact of BBD on daily life functioning was reported by 42% of patients. CONCLUSIONS: These data underscore that standard screening for BBD is needed and that the CBBDQ could be of added value to optimize DMD care.

The lumbosacral angle does not reflect progressive tethered cord syndrome in children with spinal dysraphism.

PURPOSE: Our goal was to validate the hypothesis that the lumbosacral angle (LSA) increases in children with spinal dysraphism who present with progressive symptoms and signs of tethered cord syndrome (TCS), and if so, to determine for which different types and/or levels the LSA would be a valid indicator of progressive TCS. Moreover, we studied the influence of surgical untethering and eventual retethering on the LSA. METHODS: We retrospectively analyzed the data of 33 children with spinal dysraphism and 33 controls with medulloblastoma. We measured the LSA at different moments during follow-up and correlated this with progression in symptomatology. RESULTS: LSA measurements had an acceptable intra- and interobserver variability, however, some children with severe deformity of the caudal part of the spinal column, and for obvious reasons those with caudal regression syndrome were excluded. LSA measurements in children with spinal dysraphism were significantly different from the control group (mean LSA change, 21.0° and 3.1° respectively). However, both groups were not age-matched, and when dividing both groups into comparable age categories, we no longer observed a significant difference. Moreover, we did not observe a significant difference between 26 children with progressive TCS as opposed to seven children with stable TCS (mean LSA change, 20.6° and 22.4° respectively). CONCLUSIONS: We did not observe significant differences in LSA measurements for children with clinically progressive TCS as opposed to clinically stable TCS. Therefore, the LSA does not help the clinician to determine if there is significant spinal cord tethering, nor if surgical untethering is needed.

Effect of seat surface inclination on postural control during reaching in preterm children with cerebral palsy.

BACKGROUND AND PURPOSE: Because it is debatable whether seat surface inclination improves motor function in children with cerebral palsy (CP), the effect of seat surface tilting on postural control and quality of reaching was studied. SUBJECTS: The subjects were 58 children with CP aged 2 to 11 years (34 with unilateral spastic CP, 24 with bilateral spastic CP). METHODS: During the task of reaching movements, surface electromyographic and kinematic data were recorded for posture and reaching with the dominant arm in 3 sitting conditions: horizontal seat surface, seat surface tilted forward 15 degrees, and seat surface tilted backward 15 degrees. RESULTS: In the children with unilateral spastic CP, forward tilting improved postural efficiency and quality of reaching. In the children with bilateral spastic CP, both forward and backward tilting of the seat surface was associated with more postural instability and did not affect the quality of reaching. DISCUSSION AND CONCLUSION: The results suggest that, in terms of postural control and quality of reaching, children with unilateral spastic CP benefit from a forward-tilted position and children with bilateral spastic CP benefit from a horizontal sitting position.

The juvenile head trauma syndrome - Deterioration after mild TBI: Diagnosis and clinical presentation at the Emergency Department.

BACKGROUND: Annually 14.000 children with traumatic brain injury (TBI) are admitted to the Emergency Department (ED) in the Netherlands. Presentation varies and a specific entity comprises the juvenile head trauma syndrome (JHTS) with secondary deterioration after a mild trauma. As outcome of JHTS can be fatal, early recognition is essential. AIM: To outline the epidemiology and clinical features of JHTS, in comparison to paediatric mild TBI patients without JHTS. METHODS: Retrospective study of 570 patients with mild TBI admitted to the ED of a level-one trauma centre from 2008 to 2014. Diagnosis of JHTS by experienced neurologists was compared with diagnosis by physicians at the ED. RESULTS: Physicians at the ED diagnosed JHTS more frequently (14%) compared to experienced neurologists (8%). JHTS occurred after a lucid interval varying from 5 to 225 min (mean 44 (SD 64)) with changes in consciousness. JHTS patients were younger compared to mild TBI patients (4.1 (SD 2.4) vs. 7.3 (SD 5.7), p < 0.01), (range: 1-10 years). Falls occurred more often in JHTS (84% vs. 69%, p = 0.03) and at presentation, vomiting (42% vs. 22%, p < 0.01) and changed behaviour (29% vs. 1%, p = 0.03) were more present compared to the mild TBI group. CONCLUSION AND DISCUSSION: JHTS occurs more often in children up to 10 years with falls as major cause of injury. Clues for recognition of this syndrome comprise changes in consciousness and vomiting or changed behaviour on presentation at the ED. For clinical practice, these factors should guide the decision for hospital admission or discharge.

Variants in SLC18A3, vesicular acetylcholine transporter, cause congenital myasthenic syndrome.

OBJECTIVE: To describe the clinical and genetic characteristics of presynaptic congenital myasthenic syndrome secondary to biallelic variants in SLC18A3. METHODS: Individuals from 2 families were identified with biallelic variants in SLC18A3, the gene encoding the vesicular acetylcholine transporter (VAChT), through whole-exome sequencing. RESULTS: The patients demonstrated features seen in presynaptic congenital myasthenic syndrome, including ptosis, ophthalmoplegia, fatigable weakness, apneic crises, and deterioration of symptoms in cold water for patient 1. Both patients demonstrated moderate clinical improvement on pyridostigmine. Patient 1 had a broader phenotype, including learning difficulties and left ventricular dysfunction. Electrophysiologic studies were typical for a presynaptic defect. Both patients showed profound electrodecrement on low-frequency repetitive stimulation followed by a prolonged period of postactivation exhaustion. In patient 1, this was unmasked only after isometric contraction, a recognized feature of presynaptic disease, emphasizing the importance of activation procedures. CONCLUSIONS: VAChT is responsible for uptake of acetylcholine into presynaptic vesicles. The clinical and electrographic characteristics of the patients described are consistent with previously reported mouse models of VAChT deficiency. These findings make it very likely that defects in VAChT due to variants in SLC18A3 are a cause of congenital myasthenic syndrome in humans.

Intermittent prednisone therapy in Duchenne muscular dystrophy: a randomized controlled trial.

BACKGROUND: Prednisone treatment is used to prolong ambulation in patients with Duchenne muscular dystrophy (DMD). However, since severe adverse effects often accompany prednisone treatment, it is debatable whether the benefits of prednisone treatment outweigh its adverse effects. OBJECTIVES: To study the effects of prednisone on muscle function and to determine the extent of steroid-related adverse effects and their influence on the quality of life of ambulant patients with DMD. DESIGN: A randomized, placebo-controlled, crossover trial with 6 months of treatment: prednisone or placebo (0.75 mg/kg daily) during the first 10 days of each month. After a washout period of 2 months, patients received the other regimen for an additional 6 months. SETTING: University hospital and rehabilitation center in the Netherlands. PATIENTS: Seventeen ambulant patients with DMD aged 5 to 8 years. MAIN OUTCOME MEASURE: Change in muscle function assessed by timed functional testing: running 9 m, climbing 4 standard-sized stairs, and rising from the floor to a standing position. RESULTS: The increase in time needed to run 9 m (P = .005) and to climb 4 standard-sized stairs (P = .02) was significantly lower during the prednisone period. CONCLUSIONS: Prednisone slowed deterioration of muscle function and muscle force in ambulant patients with DMD. Although adverse effects were present, patient quality of life was not affected. Therefore, short-term prednisone treatment can be recommended to preserve motor functions in ambulant patients with DMD.

Functional ability and muscle force in healthy children and ambulant Duchenne muscular dystrophy patients.

Neuromuscular disorders are characterised by progressive muscle weakness, which in time causes functional impairment. To quantify the extent of disease progression, muscle force and functional ability can be measured. Which of these parameters changes most depends on the disease stage. In a previous study, we reported normal values for muscle force obtained by hand-held dynamometry in healthy children aged 4-16 years. In the present study, we report normal values for timed functional tests in healthy children aged 4-11 years. These normal values were compared with values obtained in 16 ambulant patients with Duchenne muscular dystrophy (DMD) aged 5-8 years to study the extent of functional impairment. In ambulant patients with DMD, we found that muscle function assessed by timed functional tests (running 9 m and rising up from the floor) and muscle force assessed by hand-held dynamometry were severely impaired. However, a small reduction of muscle force was accompanied by a large reduction in functional ability. Therefore, in our group of ambulant patients with DMD, timed functional testing was the most sensitive parameter to determine the extent of disease progression. Timed functional testing may therefore be considered as an additional outcome measure in drug trials to evaluate the effects of therapy in ambulant patients with DMD and possibly in other neuromuscular disorders.

Kinematic characteristics of reaching movements in preterm children with cerebral palsy.

Kinematic characteristics of reaching movements of the dominant arm were assessed in 51 sitting preterm children who were aged 2-11 y and had cerebral palsy (CP), including 33 with spastic hemiplegia and 18 with bilateral CP (Bi-CP). Reference data of 29 typically developing children were present. The results indicated that the quality of reaching movements from the dominant arm of children with CP was significantly worse than that of typically developing children. This held true in particular for the children with Bi-CP. For example, reaching movements of children with CP took more time and consisted less often of one movement unit. The quality of reaching was related to the severity of lesion present on the neonatal ultrasound scan of the brain, the severity of motor disorder, the degree of spasticity, and the ability to perform activities of daily life. The last indicates that movements of the dominant arm in children with spastic hemiplegia and Bi-CP deserve clinical attention.

Kinematic characteristics of postural control during reaching in preterm children with cerebral palsy.

The relationships between kinematic characteristics of sitting posture during reaching movements of the dominant arm and 1) the kinematics of the reaching movement itself and 2) functional performance during daily life activities (PEDI) were assessed in 51 sitting preterm children with cerebral palsy (CP). The children were 2-11 y, 33 had spastic hemiplegia (SH) and 18 bilateral CP (Bi-CP). The data were compared with those of 26 typically developing children (TD). Sitting posture before the onset of reaching of children with CP differed from that of TD children: they sat with a more reclined pelvis and a more collapsed trunk. The more reclined pelvic position was associated with a better quality of reaching movements. The different sitting postures of pelvis and trunk were not related to functional performance during daily life activities. Displacement of the head, trunk, and pelvis of the children with CP did not differ from that of the TD children. Nevertheless, in the children with CP a more stable head, a more mobile trunk, and a more stable pelvis were related to better functional performance and/or a better quality of reaching. This suggests that physiotherapeutic guidance of children with CP should focus rather on the latter postural parameters than on the different sitting posture of pelvis and trunk.

Predictive value of clinical evaluation in the follow-up of children with a brain tumor.

BACKGROUND: During follow-up of children with a brain tumor, traditionally surveillance-imaging studies are done in addition to clinical evaluations. The purpose of this study was to determine the role of clinical evaluations by a multidisciplinary team for the detection of recurrent tumor. PROCEDURE: We retrospectively assessed the predictive value of clinical evaluation, using subsequent neuroimaging as the gold standard. Ninety-eight children with a newly diagnosed primary brain tumor were included in the study. In these patients, 393 imaging studies were done, 75 because of clinical suspicion of recurrence, and 318 for routine surveillance only. RESULTS: In 28 of these 75 imaging studies on clinical indications, a radiologic diagnosis of recurrence was made. Only 9 out of 318 routine surveillance imaging studies resulted in an unexpected diagnosis of recurrence. Thus, the overall positive predictive value of clinical evaluation was 37%; the overall negative predictive value was 97%. The negative predictive values for specific brain tumors varied from 91% (optical glioma) to 99% (primitive neuroectodermal tumors). CONCLUSIONS: An accurate multidisciplinary clinical evaluation has a very high negative predictive value. Consequently, the added value of surveillance imaging studies is limited. The role of such studies during the follow-up of children with brain tumors should be reconsidered.

Postural control during reaching in preterm children with cerebral palsy.

Postural control during reaching with the dominant arm was assessed in 58 preterm children with cerebral palsy (CP) aged 2 to 11 years, comprising 34 with spastic hemiplegia (17 males, 17 females) and 24 with bilateral spastic CP (bilateral CP; 15 male, 9 females). Assessments were made by multiple surface electromyogram (EMG) and kinematic recording. Mean gestational age at birth for the children with spastic hemiplegia and those with bilateral CP was 28.6 weeks (SEM 0.33) and 28.2 weeks (SEM 0.34) respectively; their mean birthweights were 1158 g (SEM 58) and 1190 g (SEM 59) respectively. All but one of the children with spastic hemiplegia could walk without restriction, the exception being a child who had self-mobility with limitations. In the group of children with bilateral CP, nine walked without assistive devices, 10 could walk with assistive devices, and five children needed a wheelchair for self-mobility. Comparison data of 29 typically developing children (10 males, 19 females) born at term with appropriate birthweight were available. Results indicated that in most children with CP the basic level of postural control ('direction-specificity', i.e. muscle activation on the side opposite to direction of body sway) was intact. However, the children with CP showed dysfunctions in: (1) recruitment order of the postural muscles, i.e. they exhibited a stereotyped top-down recruitment; and (2) the ability to modulate muscle contraction (that registers on EMG) to task-specific conditions. The latter dysfunction was more pronounced in children with bilateral CP than in those with spastic hemiplegia. Postural dysfunctions were correlated to some extent with the degree of disability in everyday activities as assessed by the Pediatric Evaluation of Disability Inventory.

Prognostic significance of amplitude-integrated EEG during the first 72 hours after birth in severely asphyxiated neonates.

Amplitude-integrated EEG (aEEG) is used to select patients for neuroprotective therapy after perinatal asphyxia because of its prognostic accuracy within several hours after birth. We aimed to determine the natural course of aEEG patterns during the first 72 h of life, in relation to neurologic outcome, in a group of severely asphyxiated term infants. Thirty infants, admitted to our neonatal intensive care unit from October 1998 until February 2001, were studied retrospectively. The aEEG traces obtained during the first 72 h after birth were assessed by pattern recognition: continuous normal voltage (CNV), discontinuous normal voltage (DNV), burst suppression (BS), continuous low voltage, and flat trace. Epileptic activity was also determined. The course of aEEG patterns was examined in relation to neurologic findings at 24 mo. Initially, 17 of 30 infants had severely abnormal aEEG patterns (BS or worse), which changed spontaneously to normal voltage patterns (CNV, DNV) in 7 within 48 h. The sooner the abnormalities on aEEG disappeared, the better the prognosis. The likelihood ratio of BS or worse for adverse outcome was 2.7 (95% confidence interval 1.4-5.0) between 0 and 6 h and increased to a highest value of 19 (95% confidence interval 2.8-128) between 24 and 36 h; after 48 h, it was not significant. Normal voltage patterns (CNV and DNV) up to 48 h of life were predictive for normal neurologic outcomes (negative likelihood ratios <0.3). Our findings indicate that the course of aEEG patterns adds to the prognostic value of aEEG monitoring in asphyxiated infants. Spontaneous recovery of severely abnormal aEEG patterns is not uncommon.