Search results for "Muscle Hypotonia"

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

2021

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 …

Cohen Syndrome-Associated Cataract Is Explained by VPS13B Functions in Lens Homeostasis and Is Modified by Additional Genetic Factors

2020

International audience; Purpose: Cohen syndrome (CS) is a rare genetic disorder caused by variants of the VPS13B gene. CS patients are affected with a severe form of retinal dystrophy, and in several cases cataracts also develop. The purpose of this study was to investigate the mechanisms and risk factors for cataract in CS, as well as to report on cataract surgeries in CS patients.Methods: To understand how VPS13B is associated with visual impairments in CS, we generated the Vps13b∆Ex3/∆Ex3 mouse model. Mice from 1 to 3 months of age were followed by ophthalmoscopy and slit-lamp examinations. Phenotypes were investigated by histology, immunohistochemistry, and western blot. Literature anal…

The clinical and molecular spectrum of QRICH1 associated neurodevelopmental disorder

2022

De novo variants in QRICH1 (Glutamine-rich protein 1) has recently been reported in 11 individuals with intellectual disability. The function of QRICH1 is largely unknown but it is likely to play a key role in the unfolded response of endoplasmic reticulum (ER) stress through transcriptional control of proteostasis. In this study, we present 27 additional individuals and delineate the clinical and molecular spectrum of the individuals (n=38) with QRICH1 variants. The main clinical features were mild to moderate developmental delay/intellectual disability (71%), non-specific facial dysmorphism (92%) and hypotonia (39%). Additional findings included poor weight gain (29%), short stature (29%)…

Chest Radiograph as Diagnostic Clue in a Floppy Infant

2016

Cohen syndrome is associated with major glycosylation defects

2014

International audience; Cohen syndrome (CS) is a rare autosomal recessive disorder with multisytemic clinical features due to mutations in the VPS13B gene, which has recently been described encoding a mandatory membrane protein involved in Golgi integrity. As the Golgi complex is the place where glycosylation of newly synthesized proteins occurs, we hypothesized that VPS13B deficiency, responsible of Golgi apparatus disturbance, could lead to glycosylation defects and/or mysfunction of this organelle, and thus be a cause of the main clinical manifestations of CS. The glycosylation status of CS serum proteins showed a very unusual pattern of glycosylation characterized by a significant accum…

Early-infantile onset epilepsy and developmental delay caused by bi-allelic GAD1 variants

2020

Mice lacking GAD1 show neonatal mortality, but the human phenotype associated with GAD1 disruption is poorly characterized. Neuray et al. describe six patients with biallelic GAD1 mutations, presenting with early-infantile onset epilepsy, neurodevelopmental delay, muscle weakness and non-CNS manifestations.

Inhibition of histone deacetylation rescues phenotype in a mouse model of Birk-Barel intellectual disability syndrome

2020

Mutations in the actively expressed, maternal allele of the imprinted KCNK9 gene cause Birk-Barel intellectual disability syndrome (BBIDS). Using a BBIDS mouse model, we identify here a partial rescue of the BBIDS-like behavioral and neuronal phenotypes mediated via residual expression from the paternal Kcnk9 (Kcnk9pat) allele. We further demonstrate that the second-generation HDAC inhibitor CI-994 induces enhanced expression from the paternally silenced Kcnk9 allele and leads to a full rescue of the behavioral phenotype suggesting CI-994 as a promising molecule for BBIDS therapy. Thus, these findings suggest a potential approach to improve cognitive dysfunction in a mouse model of an impri…

Redefining the MED13L syndrome

2015

Congenital cardiac and neurodevelopmental deficits have been recently linked to the mediator complex subunit 13-like protein MED13L, a subunit of the CDK8-associated mediator complex that functions in transcriptional regulation through DNA-binding transcription factors and RNA polymerase II. Heterozygous MED13L variants cause transposition of the great arteries and intellectual disability (ID). Here, we report eight patients with predominantly novel MED13L variants who lack such complex congenital heart malformations. Rather, they depict a syndromic form of ID characterized by facial dysmorphism, ID, speech impairment, motor developmental delay with muscular hypotonia and behavioral difficu…

Mutations in the Neuronal Vesicular SNARE VAMP2 Affect Synaptic Membrane Fusion and Impair Human Neurodevelopment

2019

VAMP2 encodes the vesicular SNARE protein VAMP2 (also called synaptobrevin-2). Together with its partners syntaxin-1A and synaptosomal-associated protein 25 (SNAP25), VAMP2 mediates fusion of synaptic vesicles to release neurotransmitters. VAMP2 is essential for vesicular exocytosis and activity-dependent neurotransmitter release. Here, we report five heterozygous de novo mutations in VAMP2 in unrelated individuals presenting with a neurodevelopmental disorder characterized by axial hypotonia (which had been present since birth), intellectual disability, and autistic features. In total, we identified two single-amino-acid deletions and three non-synonymous variants affecting conserved resid…

Infantile neuroaxonal dystrophy: Diagnosis by skin biopsy

1991

A child who shows progressive motor and mental deterioration after the first year of life, who has pyramidal signs, marked muscle hypotonia, but no seizures, suggests to have infantile neuroaxonal dystrophy (INAD). Beyond the age of two years, the EEG also entails characteristic findings. Diagnosis may be obtained by an ultrastructural examination of biopsied skin. The respective clinical and morphological findings are recorded and illustrated from four patients in this report.