Gene Haploinsufficiency in Three Patients With Suspected KBG Syndrome.

Mendelian disorders of the epigenetic machinery (MDEMs), also named chromatin modifying disorders, are a broad group of neurodevelopmental disorders, caused by mutations in functionally related chromatin genes. Mental retardation autosomal dominant 23 (MRD23) syndrome, due to gene mutations, falls into this group of disorders. KBG syndrome, caused by gene haploinsufficiency, is a chromatin related syndrome not formally belonging to this category.

Based on a cohort of 52,879 microarrays, recurrent intragenic FBN2 deletion encompassing exons 1-8 does not cause Beals syndrome.

Introduction: Congenital contractural arachnodactyly (CCA) is a rare connective tissue disorder, associated with heterozygous mutations in the FBN2 gene. The objective of this study was to evaluate the prevalence of an intragenic deletion encompassing exons 1-8 of FBN2 gene in Israeli population.

Materials And Methods: A search for intragenic FBN2 microdeletions was performed in two databases of chromosomal microarray analysis (CMA) - genetic laboratory of a tertiary medical center (the primary cohort) and one of the largest Israeli health maintenance organizations (replication cohort).

De Novo Variants in CNOT1, a Central Component of the CCR4-NOT Complex Involved in Gene Expression and RNA and Protein Stability, Cause Neurodevelopmental Delay.

CNOT1 is a member of the CCR4-NOT complex, which is a master regulator, orchestrating gene expression, RNA deadenylation, and protein ubiquitination. We report on 39 individuals with heterozygous de novo CNOT1 variants, including missense, splice site, and nonsense variants, who present with a clinical spectrum of intellectual disability, motor delay, speech delay, seizures, hypotonia, and behavioral problems. To link CNOT1 dysfunction to the neurodevelopmental phenotype observed, we generated variant-specific Drosophila models, which showed learning and memory defects upon CNOT1 knockdown.

A second cohort of CHD3 patients expands the molecular mechanisms known to cause Snijders Blok-Campeau syndrome.

There has been one previous report of a cohort of patients with variants in Chromodomain Helicase DNA-binding 3 (CHD3), now recognized as Snijders Blok-Campeau syndrome. However, with only three previously-reported patients with variants outside the ATPase/helicase domain, it was unclear if variants outside of this domain caused a clinically similar phenotype. We have analyzed 24 new patients with CHD3 variants, including nine outside the ATPase/helicase domain.

Loss of MBNL1 induces RNA misprocessing in the thymus and peripheral blood.

The thymus is a primary lymphoid organ that plays an essential role in T lymphocyte maturation and selection during development of one arm of the mammalian adaptive immune response. Although transcriptional mechanisms have been well documented in thymocyte development, co-/post-transcriptional modifications are also important but have received less attention. Here we demonstrate that the RNA alternative splicing factor MBNL1, which is sequestered in nuclear RNA foci by C(C)UG microsatellite expansions in myotonic dystrophy (DM), is essential for normal thymus development and function.

Diagnostic yield of multigene panel testing in an Israeli cohort: enrichment of low-penetrance variants.

Background: Carriers of pathogenic variants (PVs) in moderate-high-penetrance cancer susceptibility genes are offered tailored surveillance schemes for early cancer diagnosis. The clinical implications of low-penetrance variant carriers are less clear.

Methods: Clinical and demographic data were retrieved for a cohort of Israeli individuals who underwent oncogenetic testing by the 30-gene cancer panel at Color Genomics laboratory, between 04/2013 and 12/2018.

Root Skewing-Associated Genes Impact the Spaceflight Response of .

The observation that plant roots skew in microgravity recently refuted the long-held conviction that skewing was a gravity-dependent phenomenon. Further, spaceflight root skewing suggests that specific root morphologies and cell wall remodeling systems may be important aspects of spaceflight physiological adaptation. However, connections between skewing, cell wall modification and spaceflight physiology are currently based on inferences rather than direct tests.

De Novo Truncating Variants in the Last Exon of SEMA6B Cause Progressive Myoclonic Epilepsy.

De novo variants (DNVs) cause many genetic diseases. When DNVs are examined in the whole coding regions of genes in next-generation sequencing analyses, pathogenic DNVs often cluster in a specific region. One such region is the last exon and the last 50 bp of the penultimate exon, where truncating DNVs cause escape from nonsense-mediated mRNA decay [NMD(-) region].

The C-Fern (Ceratopteris richardii) genome: insights into plant genome evolution with the first partial homosporous fern genome assembly.

Ferns are notorious for possessing large genomes and numerous chromosomes. Despite decades of speculation, the processes underlying the expansive genomes of ferns are unclear, largely due to the absence of a sequenced homosporous fern genome. The lack of this crucial resource has not only hindered investigations of evolutionary processes responsible for the unusual genome characteristics of homosporous ferns, but also impeded synthesis of genome evolution across land plants.

A novel heterozygous loss-of-function DCC Netrin 1 receptor variant in prenatal agenesis of corpus callosum and review of the literature.

Agenesis of the corpus callosum (ACC) is a common prenatally-detected brain anomaly. Recently, an association between mutations in the DCC Netrin 1 receptor (DCC) gene and ACC, with or without mirror movements, has been demonstrated. In this manuscript, we present a family with a novel heterozygous frameshift mutation in DCC, review the available literature, and discuss the challenges involved in the genetic counseling for recently discovered disorders with paucity of medical information.

Cell-type-specific dysregulation of RNA alternative splicing in short tandem repeat mouse knockin models of myotonic dystrophy.

Short tandem repeats (STRs) are prone to expansion mutations that cause multiple hereditary neurological and neuromuscular diseases. To study pathomechanisms using mouse models that recapitulate the tissue specificity and developmental timing of an STR expansion gene, we used rolling circle amplification and CRISPR/Cas9-mediated genome editing to generate CTG expansion (CTG) knockin models of myotonic dystrophy type 1 (DM1). We demonstrate that skeletal muscle myoblasts and brain choroid plexus epithelial cells are particularly susceptible to CTG mutations and RNA missplicing.

The CHD4-related syndrome: a comprehensive investigation of the clinical spectrum, genotype-phenotype correlations, and molecular basis.

Purpose: Sifrim-Hitz-Weiss syndrome (SIHIWES) is a recently described multisystemic neurodevelopmental disorder caused by de novo variants inCHD4. In this study, we investigated the clinical spectrum of the disorder, genotype-phenotype correlations, and the effect of different missense variants on CHD4 function.

Methods: We collected clinical and molecular data from 32 individuals with mostly de novo variants in CHD4, identified through next-generation sequencing.

The yield of full BRCA1/2 genotyping in Israeli Arab high-risk breast/ovarian cancer patients.

Purpose: While the spectrum of germline mutations in BRCA1/2 genes in the Israeli Jewish population has been extensively studied, there is a paucity of data pertaining to Israeli Arab high-risk cases.

Methods: Consecutive Israeli Arab breast and/or ovarian cancer patients were recruited using an ethically approved protocol from January 2012 to February 2019. All ovarian cancer cases were referred for BRCA genotyping.

Short Tandem Repeat Expansions and RNA-Mediated Pathogenesis in Myotonic Dystrophy.

Short tandem repeat (STR) or microsatellite, expansions underlie more than 50 hereditary neurological, neuromuscular and other diseases, including myotonic dystrophy types 1 (DM1) and 2 (DM2). Current disease models for DM1 and DM2 propose a common pathomechanism, whereby the transcription of mutant (DM1) and (DM2) genes results in the synthesis of CUG and CCUG repeat expansion (CUG, CCUG) RNAs, respectively. These CUG and CCUG RNAs are toxic since they promote the assembly of ribonucleoprotein (RNP) complexes or RNA foci, leading to sequestration of Muscleblind-like (MBNL) proteins in the nucleus and global dysregulation of the processing, localization and stability of MBNL target RNAs.

From phenotyping to genotyping - bioinformatics for the busy clinician.

Bioinformatics is a new scientific field. It applies computational and analysis tools to the capture, analyze and interpret large quantities of biological data. To understand genomic information, comparative analysis of data obtained is crucial.

Gaucher disease type 3c: New patients with unique presentations and review of the literature.

Gaucher disease (GD) is the most prevalent lysosomal disorder caused by GBA mutations and abnormal glucocerebrosidase function, leading to glucocerebrosideaccumulation mainly in the liver, spleen, bone marrow, lungs, and occasionally in the central nervous system. Gaucher disease type 3c (GD3c) is a rare subtype of the subacute/chronic neuronopathic GD3, caused by homozygosity for the GBA p.Asp448His (D409H) mutation.

Chromosomal microarray vs. NIPS: analysis of 5541 low-risk pregnancies.

Purpose: To evaluate the diagnostic yield of chromosomal microarray (CMA) in pregnancies with normal ultrasound.

Methods: This retrospective cohort analysis included all pregnancies with normal ultrasound undergoing CMA testing between the years 2010 and 2016. We calculated the rate of detection of clinically significant CMA findings in the whole cohort and according to various indications.

A Unique Presentation of Infantile-Onset Colitis and Eosinophilic Disease without Recurrent Infections Resulting from a Novel Homozygous CARMIL2 Variant.

Purpose: This study aimed to characterize the clinical phenotype, genetic basis, and consequent immunological phenotype of a boy with severe infantile-onset colitis and eosinophilic gastrointestinal disease, and no evidence of recurrent or severe infections.

Methods: Trio whole-exome sequencing (WES) was utilized for pathogenic variant discovery. Western blot (WB) and immunohistochemical (IHC) staining were used for protein expression analyses.

Mutations in PIK3C2A cause syndromic short stature, skeletal abnormalities, and cataracts associated with ciliary dysfunction.

PIK3C2A is a class II member of the phosphoinositide 3-kinase (PI3K) family that catalyzes the phosphorylation of phosphatidylinositol (PI) into PI(3)P and the phosphorylation of PI(4)P into PI(3,4)P2. At the cellular level, PIK3C2A is critical for the formation of cilia and for receptor mediated endocytosis, among other biological functions. We identified homozygous loss-of-function mutations in PIK3C2A in children from three independent consanguineous families with short stature, coarse facial features, cataracts with secondary glaucoma, multiple skeletal abnormalities, neurological manifestations, among other findings.

Identification of a novel PCNT founder pathogenic variant in the Israeli Druze population.

Majewski Osteodysplastic Primordial Dwarfism type II (MOPDII) is a form of dwarfism associated with severe microcephaly, characteristic skeletal findings, distinct dysmorphic features and increased risk for cerebral infarctions. The condition is caused by bi-allelic loss-of-function variants in the gene PCNT. Here we describe the identification of a novel founder pathogenic variant c.