A novel de novo TMEM63A variant in a patient with severe hypomyelination and global developmental delay

2021 ◽  
Author(s):  
Shinobu Fukumura ◽  
Takuya Hiraide ◽  
Akiyo Yamamoto ◽  
Kousuke Tsuchida ◽  
Kazushi Aoto ◽  
...  
Keyword(s):  
Developmental Delay ◽  
De Novo ◽  
Global Developmental Delay

scholarly journals De novo variants in MPP5 cause global developmental delay and behavioral changes

2020 ◽  
Vol 29 (20) ◽  
pp. 3388-3401 ◽  
Author(s):  
Noelle Sterling ◽  
Anna R Duncan ◽  
Raehee Park ◽  
David A Koolen ◽  
Jiahai Shi ◽  
...  
Keyword(s):  
Cell Death ◽  
Developmental Delay ◽  
Cell Polarity ◽  
De Novo ◽  
Apoptotic Cell ◽  
Ventricular Zone ◽  
Behavioral Changes ◽  
Ependymal Cells ◽  
Global Developmental Delay ◽  
Apical Surface

Abstract Membrane Protein Palmitoylated 5 (MPP5) is a highly conserved apical complex protein essential for cell polarity, fate and survival. Defects in cell polarity are associated with neurologic disorders including autism and microcephaly. MPP5 is essential for neurogenesis in animal models, but human variants leading to neurologic impairment have not been described. We identified three patients with heterozygous MPP5 de novo variants (DNV) and global developmental delay (GDD) and compared their phenotypes and magnetic resonance imaging (MRI) to ascertain how MPP5 DNV leads to GDD. All three patients with MPP5 DNV experienced GDD with language delay/regression and behavioral changes. MRI ranged from normal to decreased gyral folding and microcephaly. The effects of MPP5 depletion on the developing brain were assessed by creating a heterozygous conditional knock out (het CKO) murine model with central nervous system (CNS)-specific Nestin-Cre drivers. In the het CKO model, Mpp5 depletion led to microcephaly, decreased cerebellar volume and cortical thickness. Het CKO mice had decreased ependymal cells and Mpp5 at the apical surface of cortical ventricular zone compared with wild type. Het CKO mice also failed to maintain progenitor pools essential for neurogenesis. The proportion of cortical cells undergoing apoptotic cell death increased, suggesting that cell death reduces progenitor population and neuron number. Het CKO mice also showed behavioral changes, similar to our patients. To our knowledge, this is the first report to show that variants in MPP5 are associated with GDD, behavioral abnormalities and language regression/delay. Murine modeling shows that neurogenesis is likely altered in these individuals, with cell death and skewed cellular composition playing significant roles.

Identification of de novo CSNK2A1 and CSNK2B variants in cases of global developmental delay with seizures

2019 ◽  
Vol 64 (4) ◽  
pp. 313-322 ◽  
Author(s):  
Mitsuko Nakashima ◽  
Jun Tohyama ◽  
Eiji Nakagawa ◽  
Yoshihiro Watanabe ◽  
Ch’ng Gaik Siew ◽  
...  
Keyword(s):  
Developmental Delay ◽  
De Novo ◽  
Global Developmental Delay

16p11.2 de novo microdeletion encompassing SRCAP gene in a patient with speech impairment, global developmental delay and behavioural problems

2014 ◽  
Vol 57 (11-12) ◽  
pp. 649-653 ◽  
Author(s):  
Francesca Gerundino ◽  
Giuseppina Marseglia ◽  
Chiara Pescucci ◽  
Elisabetta Pelo ◽  
Matteo Benelli ◽  
...  
Keyword(s):  
Developmental Delay ◽  
De Novo ◽  
Behavioural Problems ◽  
Global Developmental Delay ◽  
Speech Impairment

scholarly journals KCNQ2 mutations: genotype-phenotype association beyond epilepsy

2015 ◽  
Vol 42 (S1) ◽  
pp. S8-S8
Author(s):  
SE Buerki ◽  
GA Horwath ◽  
MI Van Allen ◽  
A Datta ◽  
C Boelman ◽  
...  
Keyword(s):  
Developmental Delay ◽  
Autonomic Dysfunction ◽  
De Novo ◽  
Focal Epilepsy ◽  
Missense Variant ◽  
Epileptic Encephalopathy ◽  
Global Developmental Delay ◽  
High Signal ◽  
Brain Volume Loss ◽  
Hyperkinetic Movement Disorder

Background: KCNQ2 abnormalities were described in infants with benign familial neonatal seizures (BFNS) and epileptic encephalopathy (EE). Associated features possibly include abnormal neuroimaging findings such as hypomyelination and/or T2 high signal of basal ganglia. Methods: This report describes 4 infants carrying different heterozygous KCNQ2 variants and 2 infants with 20q13.33 deletions encompassing KCNQ2 gene. Results: The different KCNQ2 mutations led to EE in 3 patients and included a novel de novo missense variant, p.Arg201Cys/c.601C>T, in an infant with severe EE and global developmental delay, hyperkinetic movement disorder, autonomic dysfunction with chronic hypoventilation, apnea, low GABA levels in CSF, and hypomyelination. She died at age 3 years of respiratory failure. One patient with BFNS and normal MRI has a previously reported c.508delG frame shift mutation in KCNQ2. Of the two de novo 22q13.33 deletions (1.2Mb versus 254.1 Kb) the larger caused a more severe phenotype, including focal epilepsy from infancy until 4 years, moderate developmental delay and diffuse brain volume loss. Conclusions: Along with varied epilepsy phenotypes and neuroimaging findings KCNQ abnormalities were associated with severe autonomic dysfunction and reduced CSF GABA levels. This might have further treatment implications, besides that the altered potassium channel function itself presents a therapeutic target.

scholarly journals X-linked neonatal-onset epileptic encephalopathy associated with a gain-of-function variant p.R660T in GRIA3

PLoS Genetics ◽  
2021 ◽  
Vol 17 (6) ◽  
pp. e1009608
Author(s):  
Jia-Hui Sun ◽  
Jiang Chen ◽  
Fernando Eduardo Ayala Valenzuela ◽  
Carolyn Brown ◽  
Diane Masser-Frye ◽  
...  
Keyword(s):  
Developmental Delay ◽  
Prolonged Exposure ◽  
De Novo ◽  
Missense Variant ◽  
Epileptic Encephalopathy ◽  
Global Developmental Delay ◽  
Decay Kinetics ◽  
Gain Of Function ◽  
Ca1 Neurons ◽  
Pathogenic Variants

The X-linked GRIA3 gene encodes the GLUA3 subunit of AMPA-type glutamate receptors. Pathogenic variants in this gene were previously reported in neurodevelopmental diseases, mostly in male patients but rarely in females. Here we report a de novo pathogenic missense variant in GRIA3 (c.1979G>C; p. R660T) identified in a 1-year-old female patient with severe epilepsy and global developmental delay. When exogenously expressed in human embryonic kidney (HEK) cells, GLUA3_R660T showed slower desensitization and deactivation kinetics compared to wildtype (wt) GLUA3 receptors. Substantial non-desensitized currents were observed with the mutant but not for wt GLUA3 with prolonged exposure to glutamate. When co-expressed with GLUA2, the decay kinetics were similarly slowed in GLUA2/A3_R660T with non-desensitized steady state currents. In cultured cerebellar granule neurons, miniature excitatory postsynaptic currents (mEPSCs) were significantly slower in R660T transfected cells than those expressing wt GLUA3. When overexpressed in hippocampal CA1 neurons by in utero electroporation, the evoked EPSCs and mEPSCs were slower in neurons expressing R660T mutant compared to those expressing wt GLUA3. Therefore our study provides functional evidence that a gain of function (GoF) variant in GRIA3 may cause epileptic encephalopathy and global developmental delay in a female subject by enhancing synaptic transmission.

scholarly journals Case Report: A Novel de novo Mutation in DNM1L Presenting With Developmental Delay, Ataxia, and Peripheral Neuropathy

2021 ◽  
Vol 9 ◽  
Author(s):  
Yanping Wei ◽  
Min Qian
Keyword(s):  
Peripheral Neuropathy ◽  
Developmental Delay ◽  
De Novo ◽  
Refractory Epilepsy ◽  
De Novo Mutation ◽  
Global Developmental Delay ◽  
Missense Mutations ◽  
Related Protein ◽  
Resonance Imaging ◽  
Genetic Results

DNM1L encodes dynamin-related protein 1 (Drp1), which is a member of the dynamin superfamily of GTPases and mediates mitochondrial and peroxisomal fission. In humans, several de novo heterozygous missense mutations in DNM1L have been reported, which were characterized by devastating courses with refractory epilepsy, myoclonus, and brain atrophy on MRI. We describe a 4.5-year-old male child harboring a novel de novo mutation in DNM1L presenting a phenotype of developmental delay, ataxia, and peripheral neuropathy. The clinical features, magnetic resonance imaging findings, and genetic results were summarized. Meanwhile, all the cases of DNM1L mutations reported were reviewed. DNM1L variants may need to be considered in phenotypes that include global developmental delay, peripheral neuropathy, and ataxia.

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