scholarly journals De novo variants in H3-3A and H3-3B are associated with neurodevelopmental delay, dysmorphic features, and structural brain abnormalities

2021 ◽  
Vol 6 (1) ◽  
Author(s):  
Volkan Okur ◽  
Zefu Chen ◽  
Liesbeth Vossaert ◽  
Sandra Peacock ◽  
Jill Rosenfeld ◽  
...  
Keyword(s):  
De Novo ◽  
Failure To Thrive ◽  
Global Developmental Delay ◽  
Death Domain ◽  
Brain Abnormalities ◽  
Neurodevelopmental Delay ◽  
Histone H3 Variant ◽  
Loss Variant ◽  
Stop Loss ◽  
Structural Brain

AbstractThe histone H3 variant H3.3, encoded by two genes H3-3A and H3-3B, can replace canonical isoforms H3.1 and H3.2. H3.3 is important in chromatin compaction, early embryonic development, and lineage commitment. The role of H3.3 in somatic cancers has been studied extensively, but its association with a congenital disorder has emerged just recently. Here we report eleven de novo missense variants and one de novo stop-loss variant in H3-3A (n = 6) and H3-3B (n = 6) from Baylor Genetics exome cohort (n = 11) and Matchmaker Exchange (n = 1), of which detailed phenotyping was conducted for 10 individuals (H3-3A = 4 and H3-3B = 6) that showed major phenotypes including global developmental delay, short stature, failure to thrive, dysmorphic facial features, structural brain abnormalities, hypotonia, and visual impairment. Three variant constructs (p.R129H, p.M121I, and p.I52N) showed significant decrease in protein expression, while one variant (p.R41C) accumulated at greater levels than wild-type control. One H3.3 variant construct (p.R129H) was found to have stronger interaction with the chaperone death domain-associated protein 6.

scholarly journals An Adolescent with a Rare De Novo Distal Trisomy 6p and Distal Monosomy 6q Chromosomal Combination

2020 ◽  
Vol 2020 ◽  
pp. 1-8
Author(s):  
Leia A. Peterman ◽  
Gail H. Vance ◽  
Erin E. Conboy ◽  
Katelynn Anderson ◽  
David D. Weaver
Keyword(s):  
De Novo ◽  
Failure To Thrive ◽  
Global Developmental Delay ◽  
Chromosome 6 ◽  
Sequencing Analysis ◽  
Whole Exome ◽  
Duplicated Collecting System ◽  
Chiari Ii ◽  
Nonallelic Homologous Recombination ◽  
Feeding Dysfunction

We report on a 12-year-old female with both a partial duplication and deletion involving chromosome 6. The duplication involves 6p25.3p24.3 (7.585 Mb) while the deletion includes 6q27q27 (6.244 Mb). This chromosomal abnormality is also described as distal trisomy 6p and distal monosomy 6q. The patient has a Chiari II malformation, hydrocephalus, agenesis of the corpus callosum, microcephaly, bilateral renal duplicated collecting system, scoliosis, and myelomeningocele associated with a neurogenic bladder and bladder reflux. Additional features have included seizures, feeding dysfunction, failure to thrive, sleep apnea, global developmental delay, intellectual disability, and absent speech. To our knowledge, our report is just the sixth case in the literature with concomitant distal 6p duplication and distal 6q deletion. Although a majority of chromosomal duplication-deletion cases have resulted from a parental pericentric inversion, the parents of our case have normal chromosomes. This is the first reported de novo case of distal 6p duplication and distal 6q deletion. Alternate explanations for the origin of the patient’s chromosome abnormalities include parental gonadal mosaicism, nonallelic homologous recombination, or potentially intrachromosomal transposition of the telomeres of chromosome 6. Nonpaternity was considered but ruled out by whole exome sequencing analysis.

De Novo TUBB2A Variant Presenting With Anterior Temporal Pachygyria

2016 ◽  
Vol 32 (1) ◽  
pp. 127-131 ◽  
Author(s):  
Lance H. Rodan ◽  
Christelle Moufawad El Achkar ◽  
Gerard T. Berry ◽  
Annapurna Poduri ◽  
Sanjay P. Prabhu ◽  
...  
Keyword(s):  
Developmental Delay ◽  
De Novo ◽  
Spastic Diplegia ◽  
Brain Abnormalities ◽  
Fourth Patient ◽  
De Novo Variant ◽  
Structural Brain

TUBB2A is a gene that has recently been reported in association with structural brain abnormalities. Only 3 cases have been reported to date with disparate brain morphologic abnormalities, although all patients have presented with developmental delay and infantile-onset epilepsy. We report a fourth patient with a de novo variant in TUBB2A that is predicted to be pathogenic, presenting with developmental delay, spastic diplegia, exaggerated startle, and anterior temporal pachygyria in the absence of epilepsy. This report serves to further delineate the phenotype of the TUBB2A-related disorders. Focal anterior temporal pachygyria may facilitate recognition of additional cases of this tubulinopathy.

scholarly journals Identification of a De Novo Xq26.2 Microduplication Encompassing FIRRE Gene in a Child with Intellectual Disability

Diagnostics ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 1009
Author(s):  
Gianmaria Miolo ◽  
Laura Bernardini ◽  
Anna Capalbo ◽  
Anna Favia ◽  
Marina Goldoni ◽  
...  
Keyword(s):  
De Novo ◽  
Copy Number Gain ◽  
Neurological Impairment ◽  
Autism Spectrum ◽  
Global Developmental Delay ◽  
Neurodevelopmental Delay ◽  
Wide Range ◽  
Non Coding Rnas ◽  
Spectrum Disorders ◽  
Regulatory Functions

Long non-coding RNAs (lncRNAs), defined as transcripts of ≥200 nucleotides not translated into protein, have been involved in a wide range of regulatory functions. Their dysregulations have been associated with diverse pathological conditions such as cancer, schizophrenia, Parkinson’s, Huntington’s, Alzheimer’s diseases and Neurodevelopmental Disorders (NDDs), including autism spectrum disorders (ASDs). We report on the case of a five-year-old child with global developmental delay carrying a de novo microduplication on chromosome Xq26.2 region characterized by a DNA copy-number gain spanning about 147 Kb (chrX:130,813,232-130,960,617; GRCh37/hg19). This small microduplication encompassed the exons 2-12 of the functional intergenic repeating RNA element (FIRRE) gene (chrX:130,836,678-130,964,671; GRCh37/hg19) that encodes for a lncRNA involved in the maintenance of chromatin repression. The association of such a genetic alteration with a severe neurodevelopmental delay without clear dysmorphic features and congenital abnormalities indicative of syndromic condition further suggests that small Xq26.2 chromosomal region microduplications containing the FIRRE gene may be responsible for clinical phenotypes mainly characterized by structural or functioning neurological impairment.

scholarly journals Association between confirmed congenital Zika infection at birth and outcomes up to 3 years of life

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Najeh Hcini ◽  
Yaovi Kugbe ◽  
Zo Hasina Linah Rafalimanana ◽  
Véronique Lambert ◽  
Meredith Mathieu ◽  
...  
Keyword(s):  
Neurological Impairment ◽  
In Utero ◽  
In Utero Exposure ◽  
Zikv Infection ◽  
Neurodevelopmental Delay ◽  
Systematic Testing ◽  
Brain Anomalies ◽  
Increased Risk ◽  
Structural Brain

AbstractLittle is known about the long-term neurological development of children diagnosed with congenital Zika infection at birth. Here, we report the imaging and clinical outcomes up to three years of life of a cohort of 129 children exposed to Zika virus in utero. Eighteen of them (14%) had a laboratory confirmed congenital Zika infection at birth. Infected neonates have a higher risk of adverse neonatal and early infantile outcomes (death, structural brain anomalies or neurologic symptoms) than those who tested negative: 8/18 (44%) vs 4/111 (4%), aRR 10.1 [3.5–29.0]. Neurological impairment, neurosensory alterations or delays in motor acquisition are more common in infants with a congenital Zika infection at birth: 6/15 (40%) vs 5/96 (5%), aRR 6.7 [2.2–20.0]. Finally, infected children also have an increased risk of subspecialty referral for suspected neurodevelopmental delay by three years of life: 7/11 (64%) vs 7/51 (14%), aRR 4.4 [1.9–10.1]. Infected infants without structural brain anomalies also appear to have an increased risk, although to a lesser extent, of neurological abnormalities. It seems paramount to offer systematic testing for congenital ZIKV infection in cases of in utero exposure and adapt counseling based on these results.

scholarly journals Genotype–phenotype correlations and novel molecular insights into the DHX30-associated neurodevelopmental disorders

2021 ◽  
Vol 13 (1) ◽  
Author(s):  
Ilaria Mannucci ◽  
Nghi D. P. Dang ◽  
Hannes Huber ◽  
Jaclyn B. Murry ◽  
Jeff Abramson ◽  
...  
Keyword(s):  
De Novo ◽  
Clinical Course ◽  
Neurodevelopmental Disorder ◽  
Global Developmental Delay ◽  
Helicase Activity ◽  
Speech Impairment ◽  
Human Phenotype ◽  
Missense Variants ◽  
The Impact ◽  
Global Translation

Abstract Background We aimed to define the clinical and variant spectrum and to provide novel molecular insights into the DHX30-associated neurodevelopmental disorder. Methods Clinical and genetic data from affected individuals were collected through Facebook-based family support group, GeneMatcher, and our network of collaborators. We investigated the impact of novel missense variants with respect to ATPase and helicase activity, stress granule (SG) formation, global translation, and their effect on embryonic development in zebrafish. SG formation was additionally analyzed in CRISPR/Cas9-mediated DHX30-deficient HEK293T and zebrafish models, along with in vivo behavioral assays. Results We identified 25 previously unreported individuals, ten of whom carry novel variants, two of which are recurrent, and provide evidence of gonadal mosaicism in one family. All 19 individuals harboring heterozygous missense variants within helicase core motifs (HCMs) have global developmental delay, intellectual disability, severe speech impairment, and gait abnormalities. These variants impair the ATPase and helicase activity of DHX30, trigger SG formation, interfere with global translation, and cause developmental defects in a zebrafish model. Notably, 4 individuals harboring heterozygous variants resulting either in haploinsufficiency or truncated proteins presented with a milder clinical course, similar to an individual harboring a de novo mosaic HCM missense variant. Functionally, we established DHX30 as an ATP-dependent RNA helicase and as an evolutionary conserved factor in SG assembly. Based on the clinical course, the variant location, and type we establish two distinct clinical subtypes. DHX30 loss-of-function variants cause a milder phenotype whereas a severe phenotype is caused by HCM missense variants that, in addition to the loss of ATPase and helicase activity, lead to a detrimental gain-of-function with respect to SG formation. Behavioral characterization of dhx30-deficient zebrafish revealed altered sleep-wake activity and social interaction, partially resembling the human phenotype. Conclusions Our study highlights the usefulness of social media to define novel Mendelian disorders and exemplifies how functional analyses accompanied by clinical and genetic findings can define clinically distinct subtypes for ultra-rare disorders. Such approaches require close interdisciplinary collaboration between families/legal representatives of the affected individuals, clinicians, molecular genetics diagnostic laboratories, and research laboratories.

scholarly journals Novel Dominant KCNQ2 Exon 7 Partial In-Frame Duplication in a Complex Epileptic and Neurodevelopmental Delay Syndrome

2020 ◽  
Vol 21 (12) ◽  
pp. 4447
Author(s):  
Pedro A. Lazo ◽  
Juan L. García ◽  
Paulino Gómez-Puertas ◽  
Íñigo Marcos-Alcalde ◽  
Cesar Arjona ◽  
...  
Keyword(s):  
Protein Function ◽  
De Novo ◽  
3D Structure ◽  
Unknown Origin ◽  
Unknown Etiology ◽  
Neurodevelopmental Delay ◽  
Calmodulin Binding ◽  
Whole Exome ◽  
Dynamics Simulations ◽  
Frame Duplication

Complex neurodevelopmental syndromes frequently have an unknown etiology, in which genetic factors play a pathogenic role. This study utilizes whole-exome sequencing (WES) to examine four members of a family with a son presenting, since birth, with epileptic-like crises, combined with cerebral palsy, severe neuromotor and developmental delay, dystonic tetraparexia, axonal motor affectation, and hyper-excitability of unknown origin. The WES study detected within the patient a de novo heterozygous in-frame duplication of thirty-six nucleotides within exon 7 of the human KCNQ2 gene. This insertion duplicates the first twelve amino acids of the calmodulin binding site I. Molecular dynamics simulations of this KCNQ2 peptide duplication, modelled on the 3D structure of the KCNQ2 protein, suggest that the duplication may lead to the dysregulation of calcium inhibition of this protein function.

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