Publications by authors named "Alyssa Ritter"

Modulation of neurotransmission is key for organismal responses to varying physiological contexts such as during infection, injury, or other stresses, as well as in learning and memory and for sensory adaptation. Roles for cell autonomous neuromodulatory mechanisms in these processes have been well described. The importance of cell non-autonomous pathways for inter-tissue signaling, such as gut-to-brain or glia-to-neuron, has emerged more recently, but the cellular mechanisms mediating such regulation remain comparatively unexplored.

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Modulation of neurotransmission is key for organismal responses to varying physiological contexts such as during infection, injury, or other stresses, as well as in learning and memory and for sensory adaptation. Roles for cell autonomous neuromodulatory mechanisms in these processes have been well described. The importance of cell non-autonomous pathways for inter-tissue signaling, such as gut-to-brain or glia-to-neuron, has emerged more recently, but the cellular mechanisms mediating such regulation remain comparatively unexplored.

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In children with hypertrophic cardiomyopathy (HCM), the genotype-phenotype association of abnormal electrocardiographic (ECG) features in the backdrop of gene positivity has not been well described. This study aimed to describe the abnormal ECG findings in children with HCM harboring who have genetic variants and determine the association with major adverse cardiac events (MACE). We retrospectively analyzed 81 variants-positive, phenotype-positive (V+P+), 66 variant-positive, phenotype-negative (V+P-), and 85 non-sarcomeric subjects.

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We report 21 families displaying neurodevelopmental differences and multiple congenital anomalies while bearing a series of rare variants in (). MAP4K4 has been implicated in many signaling pathways including c-Jun N-terminal and RAS kinases and is currently under investigation as a druggable target for multiple disorders. Using several zebrafish models, we demonstrate that these human variants are either loss-of-function or dominant-negative alleles and show that decreasing Map4k4 activity causes developmental defects.

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Background: Congenital heart disease (CHD) is the most common major congenital anomaly and causes significant morbidity and mortality. Epidemiologic evidence supports a role of genetics in the development of CHD. Genetic diagnoses can inform prognosis and clinical management.

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Eukaryotic initiation factor-4A2 (EIF4A2) is an ATP-dependent RNA helicase and a member of the DEAD-box protein family that recognizes the 5' cap structure of mRNAs, allows mRNA to bind to the ribosome, and plays an important role in microRNA-regulated gene repression. Here, we report on 15 individuals from 14 families presenting with global developmental delay, intellectual disability, hypotonia, epilepsy, and structural brain anomalies, all of whom have extremely rare de novo mono-allelic or inherited bi-allelic variants in EIF4A2. Neurodegeneration was predominantly reported in individuals with bi-allelic variants.

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MYH7, encoding the myosin heavy chain sarcomeric β-myosin heavy chain, is a common cause of both hypertrophic and dilated cardiomyopathy. Additionally, families with left ventricular noncompaction cardiomyopathy (LVNC) and congenital heart disease (CHD), typically septal defects or Ebstein anomaly, have been identified to have heterozygous pathogenic variants in MHY7. One previous case of single ventricle CHD with heart failure due to a MYH7 variant has been identified.

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Purpose: This study aimed to describe the phenotypic and molecular characteristics of ARCN1-related syndrome.

Methods: Patients with ARCN1 variants were identified, and clinician researchers were connected using GeneMatcher and physician referrals. Clinical histories were collected from each patient.

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Background: A neurodevelopmental syndrome was recently reported in four patients with heterozygous missense variants in the high-mobility-group (HMG) DNA-binding domain. The present study aimed to consolidate clinical and genetic knowledge of this syndrome.

Methods: We newly identified 17 patients with variants, predicted variant pathogenicity using in silico tests and in vitro functional assays and analysed the patients' phenotypes.

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De novo variants in QRICH1 (Glutamine-rich protein 1) has recently been reported in 11 individuals with intellectual disability (ID). The function of QRICH1 is largely unknown but it is likely to play a key role in the unfolded response of endoplasmic reticulum stress through transcriptional control of proteostasis. In this study, we present 27 additional individuals and delineate the clinical and molecular spectrum of the individuals (n = 38) with QRICH1 variants.

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Article Synopsis
  • Truncating variants in exons 33 and 34 of the SRCAP gene are linked to Floating-Harbor syndrome, a neurodevelopmental disorder with symptoms like short stature and speech delay.
  • In a study of 33 individuals with different clinical features than FLHS, most had de novo SRCAP variants, revealing shared issues like developmental delays and behavioral problems.
  • The research found distinct DNA methylation signatures for these individuals compared to FLHS, leading to the classification of their condition as "non-FLHS SRCAP-related NDD," emphasizing the relationship between variant location, DNA methylation, and clinical symptoms.
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Wiedemann-Steiner syndrome (WSS) is an autosomal dominant disorder caused by monoallelic variants in KMT2A and characterized by intellectual disability and hypertrichosis. We performed a retrospective, multicenter, observational study of 104 individuals with WSS from five continents to characterize the clinical and molecular spectrum of WSS in diverse populations, to identify physical features that may be more prevalent in White versus Black Indigenous People of Color individuals, to delineate genotype-phenotype correlations, to define developmental milestones, to describe the syndrome through adulthood, and to examine clinicians' differential diagnoses. Sixty-nine of the 82 variants (84%) observed in the study were not previously reported in the literature.

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Background: Noonan Syndrome with Multiple Lentigines (NSML) and Noonan Syndrome (NS) can be difficult to differentiate clinically in early childhood. This study aims to describe characteristics of the ventricular septum that may differentiate NSML from NS. We hypothesize that the shape of the ventricular septum determined by echocardiography correlates with genotype and may distinguish patients with NSML from those with NS.

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The NatA N-acetyltransferase complex is important for cotranslational protein modification and regulation of multiple cellular processes. The NatA complex includes the core components of NAA10, the catalytic subunit, and NAA15, the auxiliary component. Both NAA10 and NAA15 have been associated with neurodevelopmental disorders with overlapping clinical features, including variable intellectual disability, dysmorphic facial features, and, less commonly, congenital anomalies such as cleft lip or palate.

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Pathogenic variants in the homologous and highly conserved genes-CREBBP and EP300-are causal for Rubinstein-Taybi syndrome (RSTS). CREBBP and EP300 encode histone acetyltransferases (HAT) that act as transcriptional co-activators, and their haploinsufficiency causes the pathology characteristic of RSTS by interfering with global transcriptional regulation. Though generally a well-characterized syndrome, there is a clear phenotypic spectrum; rare associations have emerged with increasing diagnosis that is critical for comprehensive understanding of this rare syndrome.

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Background: Previous genetic research in pediatric cardiomyopathy (CM) has focused on pathogenic variants for diagnostic purposes, with limited data evaluating genotype-outcome correlations. We explored whether greater genetic variant burden (pathogenic or variants of unknown significance, VUS) correlates with worse outcomes.

Methods: Children with dilated CM (DCM) and hypertrophic CM (HCM) who underwent multigene testing between 2010 and 2018 were included.

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SMARCA4 encodes a central ATPase subunit in the BRG1-/BRM-associated factors (BAF) or polybromo-associated BAF (PBAF) complex in humans, which is responsible in part for chromatin remodeling and transcriptional regulation. Variants in this and other genes encoding BAF/PBAF complexes have been implicated in Coffin-Siris Syndrome, a multiple congenital anomaly syndrome classically characterized by learning and developmental differences, coarse facial features, hypertrichosis, and underdevelopment of the fifth digits/nails of the hands and feet. Individuals with SMARCA4 variants have been previously reported and appear to display a variable phenotype.

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Article Synopsis
  • * Researchers reported on 32 new individuals with confirmed KAT6B disorders, identified 24 new pathogenic variants, and suggested a classification for clinical subtypes based on phenotypic features.
  • * Key findings include increased prevalence of cerebral anomalies, optic nerve issues, and limb abnormalities, along with serious conditions like intestinal malrotation, underscoring the importance of thorough assessment in affected individuals.
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Congenital heart defects (CHD) are the most common birth defect and are both clinically and genetically heterogeneous. Truncus arteriosus (TA), characterized by a single arterial vessel arising from both ventricles giving rise to the coronary, pulmonary and systemic arteries, is rare and only responsible for 1% of all CHD. Two consanguineous families with TA were previously identified to have homozygous nonsense variants within the gene NKX2-6.

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Interstitial and terminal deletions of chromosome 4q have been described for many years and have variable phenotypes depending on the size of the deletion present. Clinical features can include developmental delay, growth difficulty, digital differences, dysmorphic features, and cardiac anomalies. Here, we present an infant with pseudohypoaldosteronism found to have a deletion of 4q31.

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NKAP is a ubiquitously expressed nucleoplasmic protein that is currently known as a transcriptional regulatory molecule via its interaction with HDAC3 and spliceosomal proteins. Here, we report a disorder of transcriptional regulation due to missense mutations in the X chromosome gene, NKAP. These mutations are clustered in the C-terminal region of NKAP where NKAP interacts with HDAC3 and post-catalytic spliceosomal complex proteins.

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