Global Developmental Impairment Research Articles

Genotype-phenotype correlation in CLCN4-related developmental and epileptic encephalopathy.

CLCN4-related disorder is a rare X-linked neurodevelopmental condition with a pathogenic mechanism yet to be elucidated. CLCN4 encodes the vesicular 2Cl-/H+ exchanger ClC-4, and CLCN4 pathogenic variants frequently result in altered ClC-4 transport activity. The precise cellular and molecular function of ClC-4 remains unknown; however, together with ClC-3, ClC-4 is thought to have a role in the ion homeostasis of endosomes and intracellular trafficking. We reviewed our research database for patients with CLCN4 variants and epilepsy, and performed thorough phenotyping. We examined the functional properties of the variants in mammalian cells using patch-clamp electrophysiology, protein biochemistry, and confocal fluorescence microscopy. Three male patients with developmental and epileptic encephalopathy were identified, with differing phenotypes. Patients #1 and #2 had normal growth parameters and normal-appearing brains on MRI, while patient #3 had microcephaly, microsomia, complete agenesis of the corpus callosum and cerebellar and brainstem hypoplasia. The p.(Gly342Arg) variant of patient #1 significantly impaired ClC-4's heterodimerization capability with ClC-3 and suppressed anion currents. The p.(Ile549Leu) variant of patient #2 and p.(Asp89Asn) variant of patient #3 both shift the voltage dependency of transport activation by 20 mV to more hyperpolarizing potentials, relative to the wild-type, with p.(Asp89Asn) favouring higher transport activity. We concluded that p.(Gly342Arg) carried by patient #1 and the p.(Ile549Leu) expressed by patient #2 impair ClC-4 transport function, while the p.(Asp89Asn) variant results in a gain-of-transport function; all three variants result in epilepsy and global developmental impairment, but with differences in epilepsy presentation, growth parameters, and presence or absence of brain malformations.

Gain-of-function and loss-of-function variants in GRIA3 lead to distinct neurodevelopmental phenotypes.

AMPA (α-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid) receptors (AMPARs) mediate fast excitatory neurotransmission in the brain. AMPARs form by homo- or heteromeric assembly of subunits encoded by the GRIA1-GRIA4 genes, of which only GRIA3 is X-chromosomal. Increasing numbers of GRIA3 missense variants are reported in patients with neurodevelopmental disorders (NDD), but only a few have been examined functionally. Here, we evaluated the impact on AMPAR function of one frameshift and 43 rare missense GRIA3 variants identified in patients with NDD by electrophysiological assays. Thirty-one variants alter receptor function and show loss-of-function or gain-of-function properties, whereas 13 appeared neutral. We collected detailed clinical data from 25 patients (from 23 families) harbouring 17 of these variants. All patients had global developmental impairment, mostly moderate (9/25) or severe (12/25). Twelve patients had seizures, including focal motor (6/12), unknown onset motor (4/12), focal impaired awareness (1/12), (atypical) absence (2/12), myoclonic (5/12) and generalized tonic-clonic (1/12) or atonic (1/12) seizures. The epilepsy syndrome was classified as developmental and epileptic encephalopathy in eight patients, developmental encephalopathy without seizures in 13 patients, and intellectual disability with epilepsy in four patients. Limb muscular hypotonia was reported in 13/25, and hypertonia in 10/25. Movement disorders were reported in 14/25, with hyperekplexia or non-epileptic erratic myoclonus being the most prevalent feature (8/25). Correlating receptor functional phenotype with clinical features revealed clinical features for GRIA3-associated NDDs and distinct NDD phenotypes for loss-of-function and gain-of-function variants. Gain-of-function variants were associated with more severe outcomes: patients were younger at the time of seizure onset (median age: 1 month), hypertonic and more often had movement disorders, including hyperekplexia. Patients with loss-of-function variants were older at the time of seizure onset (median age: 16 months), hypotonic and had sleeping disturbances. Loss-of-function and gain-of-function variants were disease-causing in both sexes but affected males often carried de novo or hemizygous loss-of-function variants inherited from healthy mothers, whereas affected females had mostly de novo heterozygous gain-of-function variants.

Safety and efficacy of ganaxolone in patients with CDKL5 deficiency disorder: results from the double-blind phase of a randomised, placebo-controlled, phase 3 trial

CDKL5 deficiency disorder (CDD) is a rare, X-linked, developmental and epileptic encephalopathy characterised by severe global developmental impairment and seizures that can begin in the first few months after birth and are often treatment refractory. Ganaxolone, an investigational neuroactive steroid, reduced seizure frequency in an open-label, phase 2 trial that included patients with CDD. We aimed to further assess the efficacy and safety of ganaxolone in patients with CDD-associated refractory epilepsy. In the double-blind phase of this randomised, placebo-controlled, phase 3 trial, done at 39 outpatient clinics in eight countries (Australia, France, Israel, Italy, Poland, Russia, the UK, and the USA), patients were eligible if they were aged 2-21 years with a pathogenic or probably pathogenic CDKL5 variant and at least 16 major motor seizures (defined as bilateral tonic, generalised tonic-clonic, bilateral clonic, atonic, or focal to bilateral tonic-clonic) per 28 days in each 4-week period of an 8-week historical period. After a 6-week prospective baseline period, patients were randomly assigned (1:1) via an interactive web response system to receive either enteral adjunctive ganaxolone or matching enteral adjunctive placebo (maximum dose 63 mg/kg per day for patients weighing ≤28 kg or 1800 mg/day for patients weighing >28 kg) for 17 weeks. Patients, caregivers, investigators (including those analysing data), trial staff, and the sponsor (other than the investigational product manager) were masked to treatment allocation. The primary efficacy endpoint was percentage change in median 28-day major motor seizure frequency from the baseline period to the 17-week double-blind phase and was analysed (using a Wilcoxon-rank sum test) in all patients who received at least one dose of trial treatment and for whom baseline data were available. Safety (compared descriptively across groups) was analysed in all patients who received at least one dose of trial treatment. This study is registered with ClinicalTrials.gov, NCT03572933, and the open-label extension phase is ongoing. Between June 25, 2018, and July 2, 2020, 114 patients were screened for eligibility, of whom 101 (median age 6 years [IQR 3 to 10]) were randomly assigned to receive either ganaxolone (n=50) or placebo (n=51). All patients received at least one dose of a study drug, but seizure frequency for one patient in the ganaxolone group was not recorded at baseline and so the primary endpoint was analysed in a population of 100 patients. There was a median percentage change in 28-day major motor seizure frequency of -30·7% (IQR -49·5 to -1·9) in the ganaxolone group and of -6·9% (-24·1 to 39·7) in the placebo group (p=0·0036). The Hodges-Lehmann estimate of median difference in responses to ganaxolone versus placebo was -27·1% (95% CI -47·9 to - 9·6). Treatment-emergent adverse events occurred in 43 (86%) of 50 patients in the ganaxolone group and in 45 (88%) of 51 patients in the placebo group. Somnolence, pyrexia, and upper respiratory tract infections occurred in at least 10% of patients in the ganaxolone group and more frequently than in the placebo group. Serious adverse events occurred in six (12%) patients in the ganaxolone group and in five (10%) patients in the placebo group. Two (4%) patients in the ganaxolone group and four (8%) patients in the placebo group discontinued the trial. There were no deaths in the double-blind phase. Ganaxolone significantly reduced the frequency of CDD-associated seizures compared with placebo and was generally well tolerated. Results from what is, to our knowledge, the first controlled trial in CDD suggest a potential treatment benefit for ganaxolone. Long-term treatment is being assessed in the ongoing open-label extension phase of this trial. Marinus Pharmaceuticals.

Genetic Generalized Epilepsy and Intrafamilial Phenotypic Variability with Distal 7q11.23 Deletion.

Background: Distal 7q11.23 deletions are variably associated with epilepsy, intellectual disability and neurobehavioural abnormalities. The relative importance of different genes in this region in contributing to different phenotypes is not clear, though HIP1 and YWHAG are both thought to play important roles. Patients and Methods: We performed thorough phenotyping on members of a family in which multiple members carried a relatively small 0.8 Mb distal 7q11.23 deletion, affecting 17 genes. Results: Two brothers and a half-brother had all inherited the 7q11.23 deletion from their mother. The eldest two both had global developmental impairment and genetic generalized epilepsy, involving absence, myoclonic or myoclonic-atonic seizures. There was no history of seizures in the mother or her youngest son, but both also had developmental impairment. Conclusion: Distal 7q11.23 deletions affecting HIP1 and YWHAG may cause developmental impairment and genetic generalized epilepsy, with considerable intrafamilial phenotypic variability.

Multicenter prospective longitudinal study in 34 patients with Dravet syndrome: Neuropsychological development in the first six years of life

The objective of this study was to identify developmental trajectories of developmental/behavioral phenotypes and possibly their relationship to epilepsy and genotype by analyzing developmental and behavioral features collected prospectively and longitudinally in a cohort of patients with Dravet syndrome (DS).Thirty-four patients from seven Italian tertiary pediatric neurology centers were enrolled in the study. All patients were examined for the SCN1A gene mutation and prospectively assessed from the first years of life with repeated full clinical observations including neurological and developmental examinations. Subjects were found to follow three neurodevelopmental trajectories. In the first group (16 patients), an initial and usually mild decline was observed between the second and the third year of life, specifically concerning visuomotor abilities, later progressing towards global involvement of all abilities. The second group (12 patients) showed an earlier onset of global developmental impairment, progressing towards a generally worse outcome. The third group of only two patients ended up with a normal neurodevelopmental quotient, but with behavioral and linguistic problems. The remaining four patients were not classifiable due to a lack of critical assessments just before developmental decline.The neurodevelopmental trajectories described in this study suggest a differential contribution of neurobiological and genetic factors. The profile of the first group, which included the largest fraction of patients, suggests that in the initial phase of the disease, visuomotor defects might play a major role in determining developmental decline.Early diagnosis of milder cases with initial visuomotor impairment may therefore provide new tools for a more accurate habilitation strategy.

Self-limited focal epilepsy and childhood apraxia of speech with WAC pathogenic variants.

Heterozygous pathogenic WAC variants cause Desanto-Shinawi syndrome; affected patients have dysmorphic features, developmental impairment and behavioral abnormalities. Seizures are reported in one quarter, including tonic-clonic, absence, and febrile seizures. This study aimed to better understand the phenotypic spectrum of epilepsy and development in Desanto-Shinawi syndrome. We identified four children with seizures and pathogenic WAC variants, including two siblings. All had global developmental impairment with language affected most severely; two had diagnoses of childhood apraxia of speech and two had autism spectrum disorder. Seizure onset age ranged from six months to 14 years. Seizures always occurred from sleep and were focal impaired awareness with motor features in three patients, with one having bilateral tonic-clonic seizures of suspected focal onset. Two patients had spontaneous seizure resolution without treatment, and the remaining two were well-controlled on monotherapy. EEG was normal in two patients; one had focal right frontal spikes in drowsiness and sleep while the last had independent centrotemporal spikes from both hemispheres, activated in sleep. All patients had heterozygous truncating pathogenic WAC variants, with negative parental testing. The findings in this cohort of patients suggest that epilepsy in Desanto-Shinawi syndrome is usually focal and self-limited, and may fall within the epilepsy-aphasia spectrum.

Ten years of evidence for the diagnostic assessment of preschoolers with prenatal alcohol exposure

The assessment of preschoolers with prenatal alcohol exposure (PAE) is challenging for many diagnostic teams and clinicians. The 2016 Canadian Fetal Alcohol Spectrum Disorder (FASD) diagnostic guidelines describe the assessments recommended for individuals with PAE in various age groups. Interpretation of brain domains constituting global impairment in preschoolers is not well described in the literature, and there has been clinical reluctance to consider the interpretation of clinical assessments as definitively diagnostic in this age group. This study describes the results of 10-year retrospective clinical data of over 300 preschoolers with PAE referred to the Manitoba FASD Centre for assessment of FASD. Preschoolers who met the criteria for a diagnosis of FASD showed significantly greater global developmental impairment, compared with those with PAE alone. They also demonstrated poorer receptive and expressive language abilities when compared with preschoolers who were not diagnosed. Preschoolers with FASD were rated as having more difficulties with executive functioning skills and adaptive functioning skills, compared to their counterparts. Significant deficits were found in fine-motor, visual-motor, and components of gross-motor skills. Importantly, significant sensory processing differences are particularly evident in preschoolers and are important in understanding behavior and in intervention planning. Together, standardized assessment of motor and sensory processing skills, with a comprehensive assessment of language, are significant predictors of FASD diagnosis for preschoolers with PAE.

Low risk of neurodevelopmental impairment among perinatally acquired HIV-infected preschool children who received early antiretroviral treatment in Thailand.

IntroductionAntiretroviral therapy (ART) is recommended in perinatally HIV‐infected (PHIV) infants immediately upon diagnosis. We aimed to compare neurodevelopmental outcomes between PHIV children who initiated ART within 12 months of life and perinatally HIV‐exposed uninfected (PHEU) children and to assess neurodevelopmental outcomes by timing of ART.MethodsThis prospective cohort study included Thai children aged 12 to 56 months who were assessed with the Mullen Scales of Early Learning (MSEL) at enrolment and at 48 weeks. Global Developmental Impairment (GDI) was defined as Early Learning Composite (ELC) ≤ 70 on the MSEL; typical developmental pattern was defined as ELC > 70 at both visits. Logistic regression was used to compare prevalence of any GDI. Predictors of changing ELC scores were analysed with generalized estimating equations linear regression model.ResultsFrom 2016 to 2017, 50 PHIV (twenty‐seven early ART within three months and twenty‐three standard ART within three to twelve months) and 100 PHEU children were enrolled. Median (IQR) age at first assessment was 28 (19 to 41) months. PHIV children had lower age‐relevant Z scores for weight, height and head circumference compared to the PHEU group (p < 0.05).The prevalence of overall GDI was 18% (95% CI 11 to 27) and 32% (95% CI 20 to 47) in PHEU and PHIV children respectively (p = 0.06). In subgroup analysis, 22% (95% CI 9 to 42) of early ART PHIV children and 44% (95% CI 23 to 66) of standard ART PHIV children had overall GDI. There was a higher rate of GDI in standard ART PHIV children (p = 0.01), but not in the early ART group (p = 0.62) when compared with PHEU children. The standard ART PHIV group demonstrated lower typical developmental pattern than both the early ART PHIV group and the PHEU group (57% vs. 77% vs. 82% respectively). Non‐attendance at nursery school was associated with changes in ELC score during study participation (adjusted coefficient −3.8; 95% CI −6.1 to −1.6, p = 0.001).ConclusionsPreschool children with HIV who initiated ART in the first three months of life had a similar rate of GDI as PHEU children. Lack of nursery school attendance predicted poor developmental trajectory outcomes among PHIV children.

Tigroid pattern of cerebral white matter involvement in chromosome 6p25 deletion syndrome with concomitant 5p15 duplication.

Sub-telomeric deletions of the short arm of chromosome 6 are a well-described clinical entity characterized by developmental impairment, hypotonia, eye abnormalities and defects in the heart and kidneys. Chromosome 5p terminal duplication is a rarer entity, associated with developmental impairment and facial dysmorphism. We report a 3-year-old patient with a chromosome 6p25.1pter deletion and chromosome 5p15.1pter duplication who had global developmental impairment and unusual cerebral white matter changes, with hypoplastic corpus callosum and cerebellar vermis on magnetic resonance imaging -brain scan. We discuss the differential diagnosis to consider in patients with this appearance on magnetic resonance imaging -brain scan and reiterate the need for chromosome analysis in patients with this pattern of developmental anomaly. Tigroid pattern of cerebral white matter involvement has not been reported in chromosomal deletion/duplication syndromes. With the increasing use of molecular karyotyping for patients with multiple congenital anomalies and developmental delay, it is important to consider the exact size and nature of chromosomal deletion/duplication, in order to provide families with prognostic information and recurrence risk. This in turn, will help provide valuable information regarding the natural history of rare chromosomal imbalances.

Clinical Neuroimaging Features and Outcome in Molybdenum Cofactor Deficiency

Molybdenum cofactor deficiency predominantly affects the central nervous system. There are limited data on long-term outcome or brain magnetic resonance imaging (MRI) features. We examined the clinical, brain MRI, biochemical, genetic, and electroencephalographic features and outcome in 8 children with a diagnosis of molybdenum cofactor deficiency observed in our institution over 10 years. Two modes of presentation were identified: early (classical) onset with predominantly epileptic encephalopathy in 6 neonates, and late (atypical) with global developmental impairment in 2 children. Children in both groups had varying degrees of motor, language, and visual impairment. There were no deaths. Brain MRI demonstrated cerebral infarction in all but one child in the atypical group. Distinctive features were best observed on early brain MRI: acute symmetrical involvement of the globus pallidi and subthalamic regions coexisting with older cerebral hemisphere infarction, chronic lesions suggestive of a prenatal insult, pontocerebellar hypoplasia with retrocerebellar cyst, and presence of a distinctive band at the cortical/subcortical white matter. Sequential imaging revealed progressive pontine atrophy and enlargement of retrocerebellar cyst. The brain MRI of one child with atypical presentation (verbal dyspraxia, lens dislocation) showed symmetrical cerebellar deep nuclei signal abnormality without cerebral infarction. Imaging pattern on early brain MRI (<1 week) may prompt the diagnosis, potentially allowing early treatment and disease modifications.

Metaplastic bone in a cortical tuber of a young patient with tuberous sclerosis complex

Cortical tubers are the most common brain lesions of the tuberous sclerosis complex (TSC).1 They vary widely in size, location, and appearance, may have a cystic or a calcified component, and are often epileptogenic.2,3 Histologically, tubers are hypomyelinated hamartomas, which are characterized by abnormal cortical lamination and are typically composed of giant or balloon cells, dysplastic neurons, and reactive astrocytes.4 We report the radiologic and pathologic findings of a resected calcified tuber identified as an epileptogenic focus. ### Case report. The patient is a 19-year-old right-handed woman with a known spontaneous TSC1 mutation. She was the product of a normal pregnancy. Seizure onset occurred at the age of 9 months and led to a diagnosis of TSC. Neuropathologic features include numerous cortical tubers and subependymal giant cell tumors (SGCT). The patient has experienced daily seizures since their onset. Multiple antiepileptic medications and other anticonvulsant treatments were tried without significant seizure control. The patient has a history of global developmental impairment. As part of the presurgical evaluation for neurosurgical intervention, an MRI showed SGCT, multiple tubers located in bilateral frontal, parietal, and occipital lobes, and a large (22 mm) T2 hypointense calcified lesion deep to the left superior frontal sulcus (figure). Review of prior scans revealed that the calcified component of this …

Progressive calcified tuber in a young male with tuberous sclerosis complex

Tubers are the most common brain lesions in tuberous sclerosis complex (TSC), and typically remain stable in size and appearance. We present the case of a young male with global developmental impairment and autistic features as well as multiple and mixed daily seizures. The patient had a prominent right frontal cortical tuber characterized by a calcified component, which changed on consecutive magnetic resonance imaging between the age of 4 and 11 years, at which time the patient underwent a lesionectomy. A poor long-term outcome is reported since the patient presents an intractable mixed seizure disorder status post-epilepsy surgery and no significant neuropsychological improvements. Histopathology findings show typical characteristics of tubers in TSC as well as numerous calcifications within the resected nodular lesion. This case supports the notion that tubers with calcified components are not necessarily static lesions and can change with time. Investigation of the relationship between the presence of calcification in tubers and epileptogenecity in a large group of patients would provide insights into the pathogenesis of the seizures and cognitive impairment and hopefully, eventually provide better treatment options for patients with TSC.

The predictive value of a preschool diagnosis of developmental language impairment

To evaluate language and cognitive outcomes in elementary school children with a prior preschool diagnosis of developmental language impairment (DLI). A cohort of preschool children, consecutively diagnosed with isolated language impairment, was reassessed in elementary school. Measures used were the communication domains of the Battelle Developmental Inventory (BDI) and the Vineland Adaptive Behavior Scale, Peabody Picture Vocabulary and Expressive One Word Picture Vocabulary. Cognition was assessed using the BDI cognitive domain. Language impairment was defined as performance more than 1.25 SD below normative means on a language measure. Specific language impairment (SLI) was defined as language impairment concurrent with a cognitive score not more than one SD below the normative mean. A total of 43/70 (61%) children were reassessed. Mean age in preschool was 3.6 +/- 0.7 years and 7.4 +/- 0.7 years at follow up. A total of 36/43 (84%) showed persistent language impairment. The mean BDI cognitive domain score was 80.0 +/- 14.2 (15/42 below -2 SDs). Only 11/42 (26%) children met current research criteria for SLI, 24/42 (57%) had language impairment but had cognitive scores more than one SD below normative means, and 4/42 (10%) had normal language and cognitive skills. No factors could be identified at intake that predicted language outcome using univariate or multivariate analysis. While a preschool diagnosis of developmental language impairment predicted persisting language impairment, the specificity of this impairment did not persist. This suggests either undiagnosed cognitive impairment in preschool children with apparently isolated language impairment or an evolving profile of more global developmental impairment.