Neurodevelopmental phenotypes associated with pathogenic variants in SLC6A1

2021 ◽  
pp. jmedgenet-2021-107694
Author(s):  
Ashley Kahen ◽  
Haluk Kavus ◽  
Alexa Geltzeiler ◽  
Catherine Kentros ◽  
Cora Taylor ◽  
...  
Keyword(s):  
Developmental Delay ◽  
De Novo ◽  
Language Disorder ◽  
Synaptic Cleft ◽  
Binding Pocket ◽  
Autism Spectrum ◽  
Gamma Aminobutyric Acid ◽  
Vineland Adaptive Behavior Scales ◽  
Care Givers ◽  
Pathogenic Variants

BackgroundSLC6A1 encodes GAT-1, a major gamma-aminobutyric acid (GABA) transporter in the brain. GAT-1 maintains neurotransmitter homeostasis by removing excess GABA from the synaptic cleft. Pathogenic variants in SLC6A1 disrupt the reuptake of GABA and are associated with a neurobehavioural phenotype.MethodsMedical history interviews, seizure surveys, Vineland Adaptive Behavior Scales Second Edition and other behavioural surveys were completed by primary care givers of 28 participants in Simons Searchlight. All participants underwent clinical whole exome sequencing or gene panel sequencing. Additional cases from the medical literature with comparable data were included.ResultsWe identified 28 individuals with largely de novo pathogenic/likely pathogenic variants including missense (15/21 or 71%) and truncating variants (6/21 or 29%). Missense variants were largely clustered around the sixth and seventh transmembrane domains, which functions as a GABA binding pocket. The phenotype of individuals with pathogenic variants in SLC6A1 includes hypotonia, intellectual disability/developmental delay, language disorder/speech delay, autism spectrum disorder, sleep issues and seizures.ConclusionPathogenic variants in SLC6A1 are associated with a clinical phenotype of developmental delay, behaviour problems and seizures. Understanding of the genotype–phenotype correlation within SLC6A1 may provide opportunities to develop new treatments for GABA-related conditions.

scholarly journals CNKSR2-related neurodevelopmental and epilepsy disorder: a cohort of 13 new families and literature review indicating a predominance of loss of function pathogenic variants

2021 ◽  
Vol 14 (1) ◽  
Author(s):  
Leigh Ann Higa ◽  
Jennifer Wardley ◽  
Christopher Wardley ◽  
Susan Singh ◽  
Timothy Foster ◽  
...  
Keyword(s):  
Developmental Delay ◽  
Sleep Disturbances ◽  
Right Hemisphere ◽  
De Novo ◽  
Autism Spectrum ◽  
Loss Of Function ◽  
Seizure Onset ◽  
Genomic Deletions ◽  
Functional Studies ◽  
Pathogenic Variants

Abstract Background Pathogenic variants in connector enhancer of kinase suppressor of Ras-2 (CNKSR2) located on the X chromosome (Xp22.12) lead to a disorder characterized by developmental delay and a characteristic seizure phenotype. To date, 20 affected males representing 13 different pathogenic variants have been published. Case presentation We identified an 8-year-old male with seizures, abnormal electroencephalogram (EEG) with epileptiform abnormalities in the right hemisphere, and developmental delay with notable loss of speech following seizure onset. Additional concerns include multiple nighttime awakenings, hyperactivity, and autism spectrum disorder. Genetic testing identified a de novo pathogenic nonsense variant in CNKSR2. Through an active family support group, an additional 12 males are described, each harboring a different CNKSR2 variant. The clinical presentation and natural history consistently show early developmental delay, sleep disturbances, and seizure onset in childhood that is initially intractable but later becomes better controlled. Virtually all of the pathogenic variants are predicted to be loss of function, including genomic deletions, nonsense variants, splice site mutations, and small insertions or deletions. Conclusions This expanded knowledge, combined with functional studies and work with animal models currently underway, will enable a better understanding and improved ability to care for individuals with CNKSR2-related neurodevelopmental and epilepsy disorder.

IL1RAPL1 Gene Deletion in a Female Patient with Developmental Delay and Continuous Spike-Wave during Sleep

2021 ◽  
Author(s):  
Evan Jiang ◽  
Mark P. Fitzgerald ◽  
Katherine L. Helbig ◽  
Ethan M. Goldberg
Keyword(s):  
Intellectual Disability ◽  
Developmental Delay ◽  
Synapse Formation ◽  
De Novo ◽  
Interleukin 1 ◽  
Autism Spectrum ◽  
Neurological Dysfunction ◽  
Behavioral Disorder ◽  
Clinical Genetic ◽  
Severe Intellectual Disability

AbstractInterleukin-1 receptor accessory protein-like 1 (IL1RAPL1) encodes a protein that is highly expressed in neurons and has been shown to regulate neurite outgrowth as well as synapse formation and synaptic transmission. Clinically, mutations in or deletions of IL1RAPL1 have been associated with a spectrum of neurological dysfunction including autism spectrum disorder and nonsyndromic X-linked developmental delay/intellectual disability of varying severity. Nearly all reported cases are in males; in the few reported cases involving females, the clinical presentation was mild or the deletion was identified in phenotypically normal carriers in accordance with X-linked inheritance. Using genome-wide microarray analysis, we identified a novel de novo 373 kb interstitial deletion of the X chromosome (Xp21.1-p21.2) that includes exons 4 to 6 of the IL1RAPL1 gene in an 8-year-old girl with severe intellectual disability and behavioral disorder with a history of developmental regression. Overnight continuous video electroencephalography revealed electrical status epilepticus in sleep (ESES). This case expands the clinical genetic spectrum of IL1RAPL1-related neurodevelopmental disorders and highlights a new genetic association of ESES.

scholarly journals Pitt Hopkins-Like Syndrome 1 with Novel CNTNAP2 Mutation in Siblings

2021 ◽  
Vol 8 ◽  
pp. 2329048X2110553
Author(s):  
Rea Mittal ◽  
Ashutosh Kumar ◽  
Roger Ladda ◽  
Gayatra Mainali ◽  
Ermal Aliu
Keyword(s):  
Developmental Delay ◽  
Focal Epilepsy ◽  
Autism Spectrum ◽  
Compound Heterozygous ◽  
Sequencing Analysis ◽  
Gait Abnormality ◽  
Pathogenic Variants ◽  
Obstructive Sleep ◽  
Management Guidance ◽  
Intragenic Deletions

Pitt Hopkins-like syndrome 1 (PTHLS1, OMIM # 610042) is an ultra-rare autosomal recessive condition with a prevalence of <1/1,000,000. Intragenic deletions of CNTNAP2 has been implicated in PTHLS1, however to our knowledge a compound heterozygous deletion of exon 4 and a c.1977_1989del13; p.V660Ffsx9 frameshift variant have not been published previously. In this case report, the proband is a seven year old female with PTHLS1, developmental delay, autism spectrum disorder, focal epilepsy, hypotonia, refractory errors, strabismus, and obstructive sleep apnea. Whole exome sequencing analysis revealed biallelic pathogenic variants of the CNTNAP2 gene. Proband has a three year old sister who has who has a similar phenotype including, developmental delay, epilepsy, gait abnormality, refractory errors, strabismus. Family variants were tested and she shared the same CNTNAP2 variants as her sister. The sisters described highlight two novel variants leading to PTHLS1. Genetic workup is essential in identification and management guidance in these populations.

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 Detailed Clinical and Psychological Phenotype of the X-linked HNRNPH2-Related Neurodevelopmental Disorder

2021 ◽  
Vol 7 (1) ◽  
pp. e551
Author(s):  
Jennifer M. Bain ◽  
Olivia Thornburg ◽  
Cheryl Pan ◽  
Donnielle Rome-Martin ◽  
Lia Boyle ◽  
...  
Keyword(s):  
Language Impairment ◽  
De Novo ◽  
Neurodevelopmental Disorder ◽  
Retrospective Chart Review ◽  
Premature Death ◽  
Parent Report ◽  
Autism Spectrum ◽  
Pathogenic Variants ◽  
Motor Problems ◽  
Cortical Visual Impairment

ObjectiveTo expand the clinical phenotype of the X-linked HNRNPH2-related neurodevelopmental disorder in 33 individuals.MethodsParticipants were diagnosed with pathogenic or likely pathogenic variants in HNRNPH2 using American College of Medical Genetics and Genomics/Association of Molecular Pathology criteria, largely identified via clinical exome sequencing. Genetic reports were reviewed. Clinical data were collected by retrospective chart review and caregiver report including standardized parent report measures.ResultsWe expand our clinical characterization of HNRNPH2-related disorders to include 33 individuals, aged 2–38 years, both females and males, with 11 different de novo missense variants, most within the nuclear localization signal. The major features of the phenotype include developmental delay/intellectual disability, severe language impairment, motor problems, growth, and musculoskeletal disturbances. Minor features include dysmorphic features, epilepsy, neuropsychiatric diagnoses such as autism spectrum disorder, and cortical visual impairment. Although rare, we report early stroke and premature death with this condition.ConclusionsThe spectrum of X-linked HNRNPH2-related disorders continues to expand as the allelic spectrum and identification of affected males increases.

scholarly journals A de novo TOP2B variant associated with global developmental delay and autism spectrum disorder

2020 ◽  
Vol 8 (3) ◽  
Author(s):  
Takuya Hiraide ◽  
Seiji Watanabe ◽  
Tomoko Matsubayashi ◽  
Kumiko Yanagi ◽  
Mitsuko Nakashima ◽  
...  
Keyword(s):  
Autism Spectrum Disorder ◽  
Developmental Delay ◽  
De Novo ◽  
Autism Spectrum ◽  
Spectrum Disorder ◽  
Global Developmental Delay

Genomics of Speech and Language Disorders

2018 ◽  
Author(s):  
Joaquin Guerra ◽  
Ramon Cacabelos
Keyword(s):  
Molecular Mechanisms ◽  
De Novo ◽  
Language Disorder ◽  
Speech Sound ◽  
Language Disorders ◽  
Communication Disorders ◽  
Autism Spectrum ◽  
Speech Disorders ◽  
Speech And Language ◽  
Co Morbidity

There are multiple factors involved in speech and language. Investigating animal models, mainly through songbirds, have allowed a better understanding of the language process. Verbal dyspraxia, dysarthria, speech sound disorder, and stuttering are some examples of speech disorders, and specific language disorder, aphasia and, dyslexia of language disorders. More complex syndromes such as Autism-spectrum disorders, Down&rsquo;s or Fragile X have more variable features. Genetic factors, such as hereditary or de novo mutations may be responsible for their development. In addition, most of them are involved in neurodevelopment with a huge range of molecular mechanisms and pathways that interact with each other, and there may be co-morbidity with other communication disorders or develop phenotypes unrelated to communication. Genes with heterogeneous functions in speech and language such as FOXP1, FOXP2, KIAA0319, ROBO1, APOE or CNTNAP2 are some examples. Epigenetic factors, especially miRNAs, influence their expressiveness. The genomics of these disorders allows us to understand language acquisition, carry out early detection strategies, genetic counseling and optimize future treatments, not only in communication disorders but also those neurological alterations that incorporate these mutations.

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