Genetic variants in DDX53 contribute to autism spectrum disorder associated with the Xp22.11 locus.

Autism spectrum disorder (ASD) exhibits an ∼4:1 male-to-female sex bias and is characterized by early-onset impairment of social/communication skills, restricted interests, and stereotyped behaviors. Disruption of the Xp22.11 locus has been associated with ASD in males.

Alpha-1 Antitrypsin Deficiency in a Young Never Smoker With Novel Pi*Null Homozygous Mutation: a Case Report.

Alpha-1 antitrypsin (AAT) deficiency is an autosomal codominant disorder caused by gene mutations. PI*Z and PI*S mutations commonly underlie this deficiency, but rarer homozygous PI* (Q0) mutations may result in a complete loss of AAT. Such rare mutations lead to severe AAT deficiency and early onset of lung disease.

Loss-of-function in RBBP5 results in a syndromic neurodevelopmental disorder associated with microcephaly.

Purpose: Epigenetic dysregulation has been associated with many inherited disorders. RBBP5 (HGNC:9888) encodes a core member of the protein complex that methylates histone 3 lysine-4 and has not been implicated in human disease.

Methods: We identify 5 unrelated individuals with de novo heterozygous variants in RBBP5.

Reanalysis of RNA sequencing data ends diagnostic odyssey and expands the phenotypic spectrum of congenital titinopathy.

Although next-generation sequencing has enabled diagnoses for many patients with Mendelian disorders, the majority remain undiagnosed. Here, we present a sibling pair who were clinically diagnosed with Escobar syndrome, however targeted gene testing was negative. Exome sequencing (ES), and later genome sequencing (GS), revealed compound heterozygous TTN variants in both siblings, a maternally inherited frameshift variant [(NM_133378.

High-Throughput Genomics Identify Novel Variants in Severe Neonatal Marfan Syndrome and Congenital Heart Defects.

Fibrillin-1 and fibrillin-2, encoded by and , respectively, play significant roles in elastic fiber assembly, with pathogenic variants causing a diverse group of connective tissue disorders such as Marfan syndrome (MFS) and congenital contractural arachnodactyly (CCD). Different genomic variations may lead to heterogeneous phenotypic features and functional consequences. Recent high-throughput sequencing modalities have allowed detection of novel variants that may guide the care for patients and inform the genetic counseling for their families.

Biallelic CRELD1 variants cause a multisystem syndrome, including neurodevelopmental phenotypes, cardiac dysrhythmias, and frequent infections.

Purpose: We sought to delineate a multisystem disorder caused by recessive cysteine-rich with epidermal growth factor-like domains 1 (CRELD1) gene variants.

Methods: The impact of CRELD1 variants was characterized through an international collaboration utilizing next-generation DNA sequencing, gene knockdown, and protein overexpression in Xenopus tropicalis, and in vitro analysis of patient immune cells.

Results: Biallelic variants in CRELD1 were found in 18 participants from 14 families.

Elucidation of bioinformatic-guided high-prospect drug repositioning candidates for DMD via Swanson linking of target-focused latent knowledge from text-mined categorical metadata.

Duchenne Muscular Dystrophy (DMD)'s complex multi-system pathophysiology, coupled with the cost-prohibitive logistics of multi-year drug screening and follow-up, has hampered the pursuit of new therapeutic approaches. Here we conducted a systematic historical and text mining-based pilot feasibility study to explore the potential of established or previously tested drugs as prospective DMD therapeutic agents. Our approach utilized a Swanson linking-inspired method to uncover meaningful yet largely hidden deep semantic connections between pharmacologically significant DMD targets and drugs developed for unrelated diseases.

Transcriptomic analysis of paired healthy human skeletal muscles to identify modulators of disease severity in DMD.

Muscle damage and fibro-fatty replacement of skeletal muscles is a main pathologic feature of Duchenne muscular dystrophy (DMD) with more proximal muscles affected earlier and more distal affected later in the disease course, suggesting that different skeletal muscle groups possess distinctive characteristics that influence their susceptibility to disease. To explore transcriptomic factors driving differential gene expression and modulating DMD skeletal muscle severity, we characterized the transcriptome of vastus lateralis (VL), a more proximal and susceptible muscle, relative to tibialis anterior (TA), a more distal and protected muscle, in 15 healthy individuals using bulk RNA sequencing to identify gene expression differences that may mediate their relative susceptibility to damage with loss of dystrophin. Matching single nuclei RNA sequencing data was generated for 3 of the healthy individuals, to infer cell composition in the bulk RNA sequencing dataset and to improve mapping of differentially expressed genes to their cell source of expression.

Full-length Isoform Sequencing for Resolving the Molecular Basis of Charcot-Marie-Tooth 2A.

Objectives: Transcript sequencing of patient-derived samples has been shown to improve the diagnostic yield for solving cases of suspected Mendelian conditions, yet the added benefit of full-length long-read transcript sequencing is largely unexplored.

Methods: We applied short-read and full-length transcript sequencing and mitochondrial functional studies to a patient-derived fibroblast cell line from an individual with neuropathy that previously lacked a molecular diagnosis.

Results: We identified an intronic homozygous c.

RAF1 deficiency causes a lethal syndrome that underscores RTK signaling during embryogenesis.

Somatic and germline gain-of-function point mutations in RAF, one of the first oncogenes to be discovered in humans, delineate a group of tumor-prone syndromes known as the RASopathies. In this study, we document the first human phenotype resulting from the germline loss-of-function of the proto-oncogene RAF1 (a.k.

De novo variants in MRTFB have gain-of-function activity in Drosophila and are associated with a novel neurodevelopmental phenotype with dysmorphic features.

Purpose: Myocardin-related transcription factor B (MRTFB) is an important transcriptional regulator, which promotes the activity of an estimated 300 genes but is not known to underlie a Mendelian disorder.

Methods: Probands were identified through the efforts of the Undiagnosed Disease Network. Because the MRTFB protein is highly conserved between vertebrate and invertebrate model organisms, we generated a humanized Drosophila model expressing the human MRTFB protein in the same spatial and temporal pattern as the fly gene.

SATB1 Chromatin Loops Regulate Megakaryocyte/Erythroid Progenitor Expansion by Facilitating HSP70 and GATA1 Induction.

Diamond Blackfan anemia (DBA) is an inherited bone marrow failure syndrome associated with severe anemia, congenital malformations, and an increased risk of developing cancer. The chromatin-binding special AT-rich sequence-binding protein-1 (SATB1) is downregulated in megakaryocyte/erythroid progenitors (MEPs) in patients and cell models of DBA, leading to a reduction in MEP expansion. Here we demonstrate that SATB1 expression is required for the upregulation of the critical erythroid factors heat shock protein 70 (HSP70) and GATA1 which accompanies MEP differentiation.

Full-length isoform sequencing for resolving the molecular basis of Charcot-Marie-Tooth 2A.

Objectives: Transcript sequencing of patient derived samples has been shown to improve the diagnostic yield for solving cases of likely Mendelian disorders, yet the added benefit of full-length long-read transcript sequencing is largely unexplored.

Methods: We applied short-read and full-length isoform cDNA sequencing and mitochondrial functional studies to a patient-derived fibroblast cell line from an individual with neuropathy that previously lacked a molecular diagnosis.

Results: We identified an intronic homozygous c.

Evaluating Genetic Modifiers of Duchenne Muscular Dystrophy Disease Progression Using Modeling and MRI.

Background And Objectives: Duchenne muscular dystrophy (DMD) is a progressive muscle degenerative disorder with a well-characterized disease phenotype but considerable interindividual heterogeneity that is not well understood. The aim of this study was to evaluate the effects of dystrophin variations and genetic modifiers of DMD on rate and age of muscle replacement by fat.

Methods: One hundred seventy-five corticosteroid treated participants from the ImagingDMD natural history study underwent repeated magnetic resonance spectroscopy (MRS) of the vastus lateralis (VL) and soleus (SOL) to determine muscle fat fraction (FF).

INTS13 variants causing a recessive developmental ciliopathy disrupt assembly of the Integrator complex.

Oral-facial-digital (OFD) syndromes are a heterogeneous group of congenital disorders characterized by malformations of the face and oral cavity, and digit anomalies. Mutations within 12 cilia-related genes have been identified that cause several types of OFD, suggesting that OFDs constitute a subgroup of developmental ciliopathies. Through homozygosity mapping and exome sequencing of two families with variable OFD type 2, we identified distinct germline variants in INTS13, a subunit of the Integrator complex.

Single nuclei transcriptomics of muscle reveals intra-muscular cell dynamics linked to dystrophin loss and rescue.

In Duchenne muscular dystrophy, dystrophin loss leads to chronic muscle damage, dysregulation of repair, fibro-fatty replacement, and weakness. We develop methodology to efficiently isolate individual nuclei from minute quantities of frozen skeletal muscle, allowing single nuclei sequencing of irreplaceable archival samples and from very small samples. We apply this method to identify cell and gene expression dynamics within human DMD and mdx mouse muscle, characterizing effects of dystrophin rescue by exon skipping therapy at single nuclei resolution.

RABENOSYN separation-of-function mutations uncouple endosomal recycling from lysosomal degradation, causing a distinct Mendelian disorder.

Rabenosyn (RBSN) is a conserved endosomal protein necessary for regulating internalized cargo. Here, we present clinical, genetic, cellular and biochemical evidence that two distinct RBSN missense variants are responsible for a novel Mendelian disorder consisting of progressive muscle weakness, facial dysmorphisms, ophthalmoplegia and intellectual disability. Using exome sequencing, we identified recessively acting germline alleles p.

Modeling Patient-Specific Muscular Dystrophy Phenotypes and Therapeutic Responses in Reprogrammed Myotubes Engineered on Micromolded Gelatin Hydrogels.

models of patient-derived muscle allow for more efficient development of genetic medicines for the muscular dystrophies, which often present mutation-specific pathologies. One popular strategy to generate patient-specific myotubes involves reprogramming dermal fibroblasts to a muscle lineage through MyoD induction. However, creating physiologically relevant, reproducible tissues exhibiting multinucleated, aligned myotubes with organized striations is dependent on the introduction of physicochemical cues that mimic the native muscle microenvironment.

Downregulation of SATB1 by miRNAs reduces megakaryocyte/erythroid progenitor expansion in preclinical models of Diamond-Blackfan anemia.

Diamond-Blackfan Anemia (DBA) is an inherited bone marrow failure syndrome that is associated with anemia, congenital anomalies, and cancer predisposition. It is categorized as a ribosomopathy, because more than 80% or patients have haploinsufficiency of either a small or large subunit-associated ribosomal protein (RP). The erythroid pathology is due predominantly to a block and delay in early committed erythropoiesis with reduced megakaryocyte/erythroid progenitors (MEPs).

Case Report: Whole Exome Sequencing Identifies Compound Heterozygous Variants in Gene Causing Juvenile Hypertrophic Cardiomyopathy.

We report a case of hypertrophic cardiomyopathy and lactic acidosis in a 3-year-old female. Cardiac and skeletal muscles biopsies exhibited mitochondrial hyperplasia with decreased complex IV activity. Whole exome sequencing identified compound heterozygous variants, p.