A Recurrent De Novo PACS2 Heterozygous Missense Variant Causes Neonatal-Onset Developmental Epileptic Encephalopathy, Facial Dysmorphism, and Cerebellar Dysgenesis.

Developmental and epileptic encephalopathies (DEEs) represent a large clinical and genetic heterogeneous group of neurodevelopmental diseases. The identification of pathogenic genetic variants in DEEs remains crucial for deciphering this complex group and for accurately caring for affected individuals (clinical diagnosis, genetic counseling, impacting medical, precision therapy, clinical trials, etc.). Whole-exome sequencing and intensive data sharing identified a recurrent de novo PACS2 heterozygous missense variant in 14 unrelated individuals. Their phenotype was characterized by epilepsy, global developmental delay with or without autism, common cerebellar dysgenesis, and facial dysmorphism. Mixed focal and generalized epilepsy occurred in the neonatal period, controlled with difficulty in the first year, but many improved in early childhood. PACS2 is an important PACS1 paralog and encodes a multifunctional sorting protein involved in nuclear gene expression and pathway traffic regulation. Both proteins harbor cargo(furin)-binding regions (FBRs) that bind cargo proteins, sorting adaptors, and cellular kinase. Compared to the defined PACS1 recurrent variant series, individuals with PACS2 variant have more consistently neonatal/early-infantile-onset epilepsy that can be challenging to control. Cerebellar abnormalities may be similar but PACS2 individuals exhibit a pattern of clear dysgenesis ranging from mild to severe. Functional studies demonstrated that the PACS2 recurrent variant reduces the ability of the predicted autoregulatory domain to modulate the interaction between the PACS2 FBR and client proteins, which may disturb cellular function. These findings support the causality of this recurrent de novo PACS2 heterozygous missense in DEEs with facial dysmorphim and cerebellar dysgenesis.

Variants in TCF20 in neurodevelopmental disability: description of 27 new patients and review of literature.

PURPOSE: To define the clinical characteristics of patients with variants in TCF20, we describe 27 patients, 26 of whom were identified via exome sequencing. We compare detailed clinical data with 17 previously reported patients. METHODS: Patients were ascertained through molecular testing laboratories performing exome sequencing (and other testing) with orthogonal confirmation; collaborating referring clinicians provided detailed clinical information. RESULTS: The cohort of 27 patients all had novel variants, and ranged in age from 2 to 68 years. All had developmental delay/intellectual disability. Autism spectrum disorders/autistic features were reported in 69%, attention disorders or hyperactivity in 67%, craniofacial features (no recognizable facial gestalt) in 67%, structural brain anomalies in 24%, and seizures in 12%. Additional features affecting various organ systems were described in 93%. In a majority of patients, we did not observe previously reported findings of postnatal overgrowth or craniosynostosis, in comparison with earlier reports. CONCLUSION: We provide valuable data regarding the prognosis and clinical manifestations of patients with variants in TCF20.

Antiseizure effect of MEK inhibitor in a child with neurofibromatosis type 1-Developmental and epileptic encephalopathy and optic pathway glioma.

BACKGROUND: Neurofibromatosis type 1 (NF1) is an autosomal dominant genetic disorder due to a mutation in NF1 gene, resulting in phenotypically heterogeneous systemic manifestations. Patients with NF1 are prone to develop neoplasms of the central nervous system (CNS) and are particularly at risk for optic pathway gliomas (OPG). Epilepsy is another recognized neurologic complication in patients with NF1, with a prevalence estimated between 4% and 14%. Several case reports and early phase clinical trials have demonstrated that the mitogen-activated protein kinase inhibitors (MEKi) are effective in NF1-low-grade gliomas (LGGs), but their influence on seizure activity in humans has not been established. CASE STUDY: Here, we report a patient with NF1 and developmental and epileptic encephalopathy (DEE) harboring pharmacoresistant tonic seizures, and progressive optic pathway glioma (OPG). By using a MEKi therapy for her OPG, we observed an end to epileptic seizures as well as a significant improvement of interictal EEG abnormalities, despite a lack of tumor reduction. CONCLUSION: MEK inhibitor therapy should be considered for patients with NF1 and refractory epilepsy.

Drosophila functional screening of de novo variants in autism uncovers damaging variants and facilitates discovery of rare neurodevelopmental diseases.

Individuals with autism spectrum disorder (ASD) exhibit an increased burden of de novo mutations (DNMs) in a broadening range of genes. While these studies have implicated hundreds of genes in ASD pathogenesis, which DNMs cause functional consequences in vivo remains unclear. We functionally test the effects of ASD missense DNMs using Drosophila through "humanization" rescue and overexpression-based strategies. We examine 79 ASD variants in 74 genes identified in the Simons Simplex Collection and find 38% of them to cause functional alterations. Moreover, we identify GLRA2 as the cause of a spectrum of neurodevelopmental phenotypes beyond ASD in 13 previously undiagnosed subjects. Functional characterization of variants in ASD candidate genes points to conserved neurobiological mechanisms and facilitates gene discovery for rare neurodevelopmental diseases.

Multisystem disorders, severe developmental delay and seizures in two affected siblings, expanding the phenotype of PIGC deficiency.

PIGC (OMIM 601730) encodes the PIGC protein, which is part of an enzyme complex involved in the biosynthesis of the glycosylphosphatidylinositol protein anchor. The other proteins in the complex include PIGA, PIGH, PIGQ, PIGY, PIGP and DPM2. Homozygous and compound heterozygous mutations in PIGC have recently been described to cause severe global developmental delay, intellectual disability, and seizures in two unrelated families, without indication of another system involvement or dysmorphism. Here we describe two siblings, born to second cousin parents, displaying severe psychomotor delay, seizures, organomegaly, cardiopulmonary anomalies, and similar facial dysmorphism. Exome sequencing in the boy revealed a homozygous variant in PIGC gene, c.12_13insTTGTGACTAACA leading to a premature stop codon p.(Gln4_Pro5insLeu*). His affected sister was also found to be homozygous, and their parents were found to be heterozygous. This is the first detailed clinical description of two related patients suggesting that PIGC deficiency can cause a severe recognisable phenotype including multisystem disorders, in association to previously reported severe developmental delay and seizures.

Clinical and molecular description of 19 patients with GATAD2B-Associated Neurodevelopmental Disorder (GAND).

De novo pathogenic variants in the GATAD2B gene have been associated with a syndromic neurodevelopmental disorder (GAND) characterized by severe intellectual disability (ID), impaired speech, childhood hypotonia, and dysmorphic features. Since its first description in 2013, nine patients have been reported in case reports and a series of 50 patients was recently published, which is consistent with the relative frequency of GATAD2B pathogenic variants in public databases. We report the detailed phenotype of 19 patients from various ethnic backgrounds with confirmed pathogenic GATAD2B variants including intragenic deletions. All individuals presented developmental delay with a median age of 2.5 years for independent walking and of 3 years for first spoken words. GATAD2B variant carriers showed very little subsequent speech progress, two patients over 30 years of age remaining non-verbal. ID was mostly moderate to severe, with one profound and one mild case, which shows a wider spectrum of disease severity than previously reported. We confirm macrocephaly as a major feature in GAND (53%). Most common dysmorphic features included broad forehead, deeply set eyes, hypertelorism, wide nasal base, and pointed chin. Conversely, prenatal abnormalities, non-cerebral malformations, epilepsy, and autistic behavior were uncommon. Other features included feeding difficulties, behavioral abnormalities, and unspecific abnormalities on brain MRI. Improving our knowledge of the clinical phenotype is essential for correct interpretation of the molecular results and accurate patient management.

Repair of Cranial Bone Defects in Children Using Synthetic Hydroxyapatite Cranioplasty (CustomBone).

BACKGROUND: In pediatric cases, the use of autologous bone tissue to repair cranial bone defects is often impossible. The synthetic hydroxyapatite bone substitute (CustomBone) can be a good alternative, especially in case of a large bone defect that has to be repaired. METHODS: This study focuses on a pediatric series of 30 children who underwent cranioplasty with a CustomBone implant. Patient age ranged from 8 months to 16 years, with a mean age of 7 years and 8 months. The most common indication for cranioplasty was posttraumatic decompressive craniectomy. RESULTS: No complications were reported. Cosmetic results were satisfactory in every patient. Only 1 implant had to be changed after severe head trauma because of an epileptic seizure in the early postoperative period. In all patients, cerebral blood flow improved during the postoperative phase. Complete implant osteointegration is a long process because mean time to begin was 13 months (range, 3-22 months). Mean patient follow-up was 6.7 years. Successful prosthesis integration depends on the accuracy of the preoperative model. The minimum thickness of the implant (4 mm) represents a challenge in very young children, but we used it with success in this series. Moreover, high costs represent another limitation for its use. CONCLUSIONS: The CustomBone implant meets all necessary conditions for good clinical outcome: excellent protective properties, restoration of normal intracranial physiology, satisfactory cosmetic results, good integration in the autologous bone, and good resistance in case of trauma.

Isolated Antenatal Hydrocephalus After Fetal Exposure to Misoprostol: Teratogenic Effect of the Cytotec?

BACKGROUND: Misoprostol is often used for termination of pregnancy in France and other countries. However, some pregnancies are continued after taking the drug and congenital malformations are known to be the consequence of fetal exposure to misoprostol, among them hydrocephalus. The type of hydrocephalus in case of misoprostol exposure is not known. CASE DESCRIPTION: We report the first case in the literature of an obstructive hydrocephalus due to an aqueduct of Sylvius stenosis diagnosed during pregnancy after misoprostol intake. CONCLUSIONS: The possible physiopathologic implications of the drug regarding the genesis of this malformation are discussed.

Postnatal Management of Myelomeningocele: Outcome with a Multidisciplinary Team Experience.

INTRODUCTION: Myelomeningocele (MMC) is a complex neural tube defect. Few studies report the results of modern postnatal management. The goal of this study was to report the long-term outcome of a multidisciplinary approach of patients with MMC. METHODS: Forty-six MMCs were included. Clinical status was evaluated prospectively. RESULTS: Mean follow-up was 8.1 years. The level of the malformation was sacral or lower lumbar (≤L4) in 27 cases, higher lumbar (between L1 and L3) in 5 cases, and thoracic in 14 cases. A Chiari II malformation was present at birth in 78.3% of the cases. Seventy-six percent of the patients were operated on within the first 24 hours of life. Sixty-one percent needed a cerebrospinal fluid diversion procedure. Seven patients underwent a second surgery for a retethering of the spine. Eighty percent presented with orthopedic problems. Sixty-five percent of our patients were able to walk. Only 13% of patients had a normal urinary elimination. Two groups of patients were identified: one group with a malformation at the level of L4 or below (group 1) and another group with a malformation strictly above L4 (group 2). Group 1 had significantly better outcome. CONCLUSIONS: This series proves that modern multidisciplinary postnatal management of MMC is effective. In the light of these results and of the results of prenatal management of MMC, prenatal surgery seems to be a highly valuable tool to improve the outcome of patients with high lesions (level ≥L3).

Complete Reversibility of the Chiari Type II Malformation After Postnatal Repair of Myelomeningocele.

OBJECTIVE: It was believed that Chiari type II malformation (CM-II) was always present in a myelomeningocele (MMC). In fact, it is associated in about 80% of cases. Improvement of the hindbrain herniation after prenatal closure of MMC has challenged the idea that this condition was irreversible. Only 2 studies report ascent of the cerebellar tonsil after postnatal closure. This work aimed to study a large group of patients with MMC who benefited from a postnatal repair to evaluate the rate of long-term total reversibility of CM-II. METHODS: Sixty-one patients were included. Mean time of follow-up was 8.1 years. The presence of CM-II after closure of the MMC was assessed on the most recent brain scan available for each patient. RESULTS: Forty-seven patients (77%) had a CM-II at birth (confirmed before the MMC repair). There was a significant correlation between the level of the malformation and the presence of a CM-II at birth (P = 0.003). After MMC closure, only 28 (45.9%) patients had a remaining CM-II. The reversibility rate was 40.4%. The reversibility was higher in lower level malformations (P = 0.004). The number of patients treated for hydrocephalus was significantly higher in the group of patients with remaining CM-II (P = 0.004). Only 11.5% of the children needed surgery for a symptomatic CM-II. CONCLUSIONS: MMC is not always associated with CM-II. The outcome of CM-II has improved. Postnatal closure can reverse the CM-II. This must be kept in mind when analyzing the result of prenatal series.

Stroke by carotid artery complete occlusion in Kawasaki disease: case report and review of literature.

BACKGROUND: Kawasaki disease is an acute and time-limited systemic vasculitis primarily affecting young children. PATIENT: We describe an 18-month-old girl with Kawasaki disease who developed cerebral infarction following complete occlusion of her right internal carotid artery. RESULTS: The occlusion occurred 10 days after the onset of fever, while she was on high-dose aspirin, and the day after she received intravenous immunoglobulin treatment. We present the first literature review on this very rare complication. CONCLUSION: Stroke is a rare neurological complication in Kawasaki disease. Optimal treatment should be begun as soon as possible after diagnosis. Intravenous immunoglobulins seem to reduce the cerebrovascular complications, but evaluation of hydration status is strongly recommended before performing such treatment.