Publications by authors named "David A Sweetser"

E3 ubiquitin ligases have been linked to developmental diseases including autism, Angelman syndrome (UBE3A), and Johanson-Blizzard syndrome (JBS) (UBR1). Here, we report variants in the E3 ligase UBR5 in 29 individuals presenting with a neurodevelopmental syndrome that includes developmental delay, autism, intellectual disability, epilepsy, movement disorders, and/or genital anomalies. Their phenotype is distinct from JBS due to the absence of exocrine pancreatic insufficiency and the presence of autism, epilepsy, and, in some probands, a movement disorder.

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Pitt-Hopkins syndrome (PTHS) is a neurodevelopmental disorder caused by pathogenic variants in TCF4, leading to intellectual disability, specific morphological features, and autonomic nervous system dysfunction. Epigenetic dysregulation has been implicated in PTHS, prompting the investigation of a DNA methylation (DNAm) "episignature" specific to PTHS for diagnostic purposes and variant reclassification and functional insights into the molecular pathophysiology of this disorder. A cohort of 67 individuals with genetically confirmed PTHS and three individuals with intellectual disability and a variant of uncertain significance (VUS) in TCF4 were studied.

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FRY-like transcription coactivator (FRYL) belongs to a Furry protein family that is evolutionarily conserved from yeast to humans. The functions of FRYL in mammals are largely unknown, and variants in FRYL have not previously been associated with a Mendelian disease. Here, we report fourteen individuals with heterozygous variants in FRYL who present with developmental delay, intellectual disability, dysmorphic features, and other congenital anomalies in multiple systems.

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Protein UFMylation downstream of the E1 enzyme UBA5 plays essential roles in development and endoplasmic reticulum stress. Variants in the gene are associated with developmental and epileptic encephalopathy 44 (DEE44), an autosomal recessive disorder characterized by early-onset encephalopathy, movement abnormalities, global developmental delay, intellectual disability, and seizures. DEE44 is caused by at least 12 different missense variants described as loss of function (LoF), but the relationships between genotypes and molecular or clinical phenotypes remain to be established.

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Identities of distinct neuron subtypes are specified during embryonic development, then maintained during post-natal maturation. In cerebral cortex, mechanisms controlling early acquisition of neuron-subtype identities have become increasingly understood. However, mechanisms controlling neuron-subtype identity stability during post-natal maturation are largely unexplored.

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Heterogeneous nuclear ribonucleoprotein C (HNRNPC) is an essential, ubiquitously abundant protein involved in mRNA processing. Genetic variants in other members of the HNRNP family have been associated with neurodevelopmental disorders. Here, we describe 13 individuals with global developmental delay, intellectual disability, behavioral abnormalities, and subtle facial dysmorphology with heterozygous HNRNPC germline variants.

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Protein UFMylation downstream of the E1 enzyme UBA5 plays essential roles in development and ER stress. Variants in the gene are associated with developmental and epileptic encephalopathy 44 (DEE44), an autosomal recessive disorder characterized by early-onset encephalopathy, movement abnormalities, global developmental delay, intellectual disability, and seizures. DEE44 is caused by at least twelve different missense variants described as loss of function (LoF), but the relationships between genotypes and molecular or clinical phenotypes remains to be established.

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Phosphoinositides (PIs) are membrane phospholipids produced through the local activity of PI kinases and phosphatases that selectively add or remove phosphate groups from the inositol head group. PIs control membrane composition and play key roles in many cellular processes including actin dynamics, endosomal trafficking, autophagy, and nuclear functions. Mutations in phosphatidylinositol 4,5 bisphosphate [PI(4,5)P2] phosphatases cause a broad spectrum of neurodevelopmental disorders such as Lowe and Joubert syndromes and congenital muscular dystrophy with cataracts and intellectual disability, which are thus associated with increased levels of PI(4,5)P2.

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EZH1, a polycomb repressive complex-2 component, is involved in a myriad of cellular processes. EZH1 represses transcription of downstream target genes through histone 3 lysine27 (H3K27) trimethylation (H3K27me3). Genetic variants in histone modifiers have been associated with developmental disorders, while EZH1 has not yet been linked to any human disease.

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Purpose: Given limited ambulatory access to genetics specialists, innovative service delivery solutions are needed. Electronic consultation (e-consult) programs are growing to connect clinicians to specialists. We explored the utilization and outcomes of a genetics and genomics e-consult program at Massachusetts General Hospital system in its first year.

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Article Synopsis
  • The MCM complex is crucial for DNA replication and plays a role in cell cycle regulation, as well as in the formation of cilia; mutations in MCM genes can lead to growth and developmental disorders like Meier-Gorlin and Seckel syndromes.
  • Two unrelated individuals with a specific mutation in the MCM6 gene showed overlapping health issues, including growth retardation and developmental delays, indicating a likely harmful effect on DNA replication.
  • Additional cases of MCM6 mutations suggest a connection to various neurodevelopmental disorders, urging healthcare professionals to consider these variants when diagnosing patients with such conditions.
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Article Synopsis
  • - Innovative service delivery models, like electronic consultations (e-Consults), are essential to improve access to genetics specialists for clinicians.
  • - Massachusetts General Hospital implemented an e-Consult service, which handled 153 requests in its first year, completing most within an average of 3.2 days.
  • - The service was primarily used by generalist providers, and 82% of clinicians who received actionable recommendations followed through, highlighting the potential of e-Consult models in genetics care access.
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( , a Polycomb Repressive Complex-2 (PRC2) component, is involved in a myriad of cellular processes through modifying histone 3 lysine27 (H3K27) residues. represses transcription of downstream target genes through H3K27 trimethylation (H3K27me3). Genetic mutations in histone modifiers have been associated with developmental disorders, while has not yet been linked to any human disease.

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MTSS2, also known as MTSS1L, binds to plasma membranes and modulates their bending. MTSS2 is highly expressed in the central nervous system (CNS) and appears to be involved in activity-dependent synaptic plasticity. Variants in MTSS2 have not yet been associated with a human phenotype in OMIM.

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Objectives: To test the hypothesis that ROSAH (retinal dystrophy, optic nerve oedema, splenomegaly, anhidrosis and headache) syndrome, caused by dominant mutation in , is an autoinflammatory disease.

Methods: This cohort study systematically evaluated 27 patients with ROSAH syndrome for inflammatory features and investigated the effect of mutations on immune signalling. Clinical, immunologic and radiographical examinations were performed, and 10 patients were empirically initiated on anticytokine therapy and monitored.

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Article Synopsis
  • - Mitochondrial complex V is crucial for ATP production, with most of its subunits encoded by nuclear genes; a specific splice variant (c.87+3A>G) in the ATP5PO gene was found in three individuals suspected of having a mitochondrial disorder.
  • - The affected individuals exhibited severe symptoms typical of Leigh syndrome, including developmental issues and cardiomyopathy, and biochemical studies revealed a significant reduction in ATP5PO protein levels and impaired complex V function.
  • - Experimental results indicated that the ATP5PO variant leads to a non-functional protein due to the skipping of an essential exon, confirming its pathogenic role and linking it to defects in mitochondrial energy production.
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The pre-mRNA-processing factor 8, encoded by PRPF8, is a scaffolding component of a spliceosome complex involved in the removal of introns from mRNA precursors. Previously, heterozygous pathogenic variants in PRPF8 have been associated with autosomal dominant retinitis pigmentosa. More recently, PRPF8 was suggested as a candidate gene for autism spectrum disorder due to the enrichment of sequence variants in this gene in individuals with neurodevelopmental disorders.

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Healthy bone homeostasis hinges upon a delicate balance and regulation of multiple processes that contribute to bone development and metabolism. While examining hematopoietic regulation by , we have uncovered a previously unappreciated role of on bone calcification using a novel null mouse model. Given the significance of osteoblasts in both hematopoiesis and bone development, this study investigated how loss of affects osteoblast function.

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Bi-allelic TECPR2 variants have been associated with a complex syndrome with features of both a neurodevelopmental and neurodegenerative disorder. Here, we provide a comprehensive clinical description and variant interpretation framework for this genetic locus. Through international collaboration, we identified 17 individuals from 15 families with bi-allelic TECPR2-variants.

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Early infantile epileptic encephalopathy-44 (EIEE44, MIM: 617132) is a previously described condition resulting from biallelic variants in , a gene involved in a ubiquitin-like post-translational modification system called UFMylation. Here we report five children from four families with biallelic pathogenic variants in All five children presented with global developmental delay, epilepsy, axial hypotonia, appendicular hypertonia, and a movement disorder, including dystonia in four. Affected individuals in all four families have compound heterozygous pathogenic variants in All have the recurrent mild c.

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Background: CTNNB1 (MIM 116806) encodes beta-catenin, an adherens junction protein that supports the integrity between layers of epithelial tissue and mediates intercellular signaling. Recently, various heterozygous germline variants in CTNNB1 have been associated with human disease, including neurodevelopmental disorder with spastic diplegia and visual defects (MIM 615075) as well as isolated familial exudative vitreoretinopathy without developmental delays or other organ system involvement (MIM 617572). From over 40 previously reported patients with CTNNB1-related neurodevelopmental disorder, many have had ocular anomalies including strabismus, hyperopia, and astigmatism.

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