Publications by authors named "Kuechler A"

While mostly de novo truncating variants in SCAF4 were recently identified in 18 individuals with variable neurodevelopmental phenotypes, knowledge on the molecular and clinical spectrum is still limited. We assembled data on 50 novel individuals with SCAF4 variants ascertained via GeneMatcher and personal communication. With detailed evaluation of clinical data, in silico predictions and structural modeling, we further characterized the molecular and clinical spectrum of the autosomal dominant SCAF4-associated neurodevelopmental disorder.

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Introduction: Congenital anomalies of the kidney and urinary tract (CAKUT) represent the most common cause of chronic kidney disease in children. Although only 20% of cases can be genetically explained, the majority remain without an identified underlying etiology. The neurodevelopmental disorder Chung-Jansen syndrome (CHUJANS) is caused by haploinsufficiency of Pleckstrin homology domain-interacting protein (PHIP) and was previously associated with genital malformations.

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  • * A 3-year study, TRANSLATE NAMSE, analyzed data from 1,577 patients, revealing that 32% received molecular diagnoses involving 370 distinct causes, primarily uncommon.
  • * The research showed that combining next-generation sequencing with advanced phenotyping methods improved diagnostic efficiency and helped identify new genotype-phenotype associations, particularly in neurodevelopmental disorders.
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The shift to a genotype-first approach in genetic diagnostics has revolutionized our understanding of neurodevelopmental disorders, expanding both their molecular and phenotypic spectra. Kleefstra syndrome (KLEFS1) is caused by EHMT1 haploinsufficiency and exhibits broad clinical manifestations. EHMT1 encodes euchromatic histone methyltransferase-1-a pivotal component of the epigenetic machinery.

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  • * The study identifies RNU4-2, a non-coding RNA gene, as a significant contributor to syndromic NDD, revealing a specific 18-base pair region with low variation that includes variants found in 115 individuals with NDD.
  • * RNU4-2 is highly expressed in the developing brain, and its variants disrupt splicing processes, indicating that non-coding genes play a crucial role in rare disorders, potentially aiding in the diagnosis of thousands with NDD worldwide.
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Utilizing trio whole-exome sequencing and a gene matching approach, we identified a cohort of 18 male individuals from 17 families with hemizygous variants in KCND1, including two de novo missense variants, three maternally inherited protein-truncating variants, and 12 maternally inherited missense variants. Affected subjects present with a neurodevelopmental disorder characterized by diverse neurological abnormalities, mostly delays in different developmental domains, but also distinct neuropsychiatric signs and epilepsy. Heterozygous carrier mothers are clinically unaffected.

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Around 60% of individuals with neurodevelopmental disorders (NDD) remain undiagnosed after comprehensive genetic testing, primarily of protein-coding genes. Increasingly, large genome-sequenced cohorts are improving our ability to discover new diagnoses in the non-coding genome. Here, we identify the non-coding RNA as a novel syndromic NDD gene.

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Background/purpose: MEGDHEL syndrome is a rare autosomal recessive metabolic disorder, which is characterized by 3-methylglutaconic aciduria with deafness-dystonia, hepatopathy, encephalopathy and Leigh-like syndrome. It is caused by biallelic pathogenic variants in the gene. Due to the unspecific symptoms and the diverse manifestations of the clinical phenotype, the diagnosis is challenging.

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SARS-CoV-2 mRNA vaccination can entail chronic fatigue/dysautonomia tentatively termed post-acute COVID-19 vaccination syndrome (PACVS). We explored receptor autoantibodies and interleukin-6 (IL-6) as somatic correlates of PACVS. Blood markers determined before and six months after first-time SARS-CoV-2 vaccination of healthy controls ( = 89; 71 females; mean/median age: 39/49 years) were compared with corresponding values of PACVS-affected persons ( = 191; 159 females; mean/median age: 40/39 years) exhibiting chronic fatigue/dysautonomia (≥three symptoms for ≥five months after the last SARS-CoV-2 mRNA vaccination) not due to SARS-CoV-2 infection and/or confounding diseases/medications.

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  • Variants of uncertain significance (VUS) present challenges in diagnosing rare diseases, and episignatures have emerged as potential biomarkers to help classify these variants.
  • A study analyzed DNA methylation data from different groups, including carriers of pathogenic variants and healthy controls, using a k-nearest-neighbour classifier to assess the predictive abilities of various episignatures.
  • Results revealed that while some signatures (ATRX, DNMT3A, KMT2D, NSD1) achieved 100% sensitivity, others (CREBBP-RSTS, CHD8) showed lower performance, indicating that not all episignatures are equally reliable for diagnostic use and highlighting the need for further validation with larger sample sizes.
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Heterozygous, pathogenic CUX1 variants are associated with global developmental delay or intellectual disability. This study delineates the clinical presentation in an extended cohort and investigates the molecular mechanism underlying the disorder in a Cux1 mouse model. Through international collaboration, we assembled the phenotypic and molecular information for 34 individuals (23 unpublished individuals).

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Pathogenic variants in cause Troyer syndrome, characterized by lower extremity spasticity and weakness, short stature and cognitive impairment, and a severe mitochondrial impairment. Herein, we report the identification of a role of Spartin in nuclear-encoded mitochondrial proteins. biallelic missense variants were detected in a 5-year-old boy with short stature, developmental delay and muscle weakness with impaired walking distance.

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Purpose: Missense variants clustering in the BTB domain region of RHOBTB2 cause a developmental and epileptic encephalopathy with early-onset seizures and severe intellectual disability.

Methods: By international collaboration, we assembled individuals with pathogenic RHOBTB2 variants and a variable spectrum of neurodevelopmental disorders. By western blotting, we investigated the consequences of missense variants in vitro.

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  • FILIP1 is a structural protein that plays a role in the function and integrity of neurons and muscles, and mutations in this protein lead to serious health issues, particularly neurological and muscular disorders.
  • Researchers studied five patients from unrelated families who had harmful FILIP1 mutations and found they exhibited a range of symptoms, such as brain malformations and muscle weakness.
  • The findings indicate that defective FILIP1 causes a recessive disorder with both neurological and muscular effects, highlighting issues like protein dysregulation and muscle damage typical of a new condition known as FILIP1opathy.
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(1) Background: The high incidence of SARS-CoV-2 infection in vaccinated persons underscores the importance of individualized re-vaccination. PanIg antibodies that act against the S1/-receptor binding domain quantified in serum by a routine diagnostic test (ECLIA, Roche) can be used to gauge the individual ex vivo capacity of SARS-CoV-2 neutralization. However, that test is not adapted to mutations in the S1/-receptor binding domain, having accumulated in SARS-CoV-2 variants.

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  • Pathogenic variants in KMT5B, a lysine methyltransferase, are linked to global developmental issues, macrocephaly, autism, and other congenital anomalies, but the disorder is still not fully understood.
  • A study examining 43 patients revealed new significant features like hypotonia and congenital heart defects not previously associated with this condition.
  • Research using patient cell lines and KMT5B knockout mice showed that these variants lead to slow growth and highlighted alterations in pathways related to nervous system development, enhancing our understanding of the disorder's molecular mechanisms.
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SOX4 is a transcription factor with pleiotropic functions required for different developmental processes, such as corticogenesis. As with all SOX proteins, it contains a conserved high mobility group (HMG) and exerts its function via interaction with other transcription factors, such as POU3F2. Recently, pathogenic variants have been identified in several patients who had clinical features overlapping with Coffin-Siris syndrome.

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In 2016 and 2018, Chung, Jansen and others described a new syndrome caused by haploinsufficiency of (pleckstrin homology domain interacting protein, OMIM *612,870) and mainly characterized by developmental delay (DD), learning difficulties/intellectual disability (ID), behavioral abnormalities, facial dysmorphism and obesity (CHUJANS, OMIM #617991). So far, alterations appear to be a rare cause of DD/ID. "Omics" technologies such as exome sequencing or array analyses have led to the identification of distinct types of alterations of , including, truncating variants, missense substitutions, splice variants and large deletions encompassing portions of the gene or the entire gene as well as adjacent genomic regions.

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  • This study introduces 31 new individuals with 22 unique genetic variants related to SYN1 disorders, detailing the prevalence of symptoms like autism, epilepsy, and intellectual disability across these cases.
  • The research also identifies specific triggers for seizures, such as water contact and routine activities, and suggests that the type of genetic mutation can influence the severity of symptoms, particularly the relationship between early seizure onset and greater intellectual challenges.
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  • - The study focuses on identifying disease-associated genes on chromosome X, which is difficult due to its unique inheritance patterns.
  • - Researchers found a notable prevalence of genes related to cognitive functions and seizures on chromosome X and identified 127 genes that may be associated with known disorders.
  • - Utilizing machine learning, the team classified 247 genes as likely disease-associated and highlighted specific damaging variants in CDK16 and TRPC5 linked to intellectual disabilities and autism spectrum disorders.
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Purpose: We describe a diagnostic procedure suitable for scheduling (re-)vaccination against severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2) according to individual state of humoral immunization. Methods: To clarify the relation between quantitative antibody measurements and humoral ex vivo immune responsiveness, we monitored 124 individuals before, during and six months after vaccination with Spikevax (Moderna, Cambridge, MA, USA). Antibodies against SARS-CoV-2 spike (S1) protein receptor-binding domain (S1-AB) and against nucleocapsid antigens were measured by chemiluminescent immunoassay (Roche).

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  • The study identifies 15 new genetic alterations linked to KCNK9 imprinting syndrome (KIS) by analyzing 47 affected individuals, revealing a diverse genetic and phenotypic spectrum.
  • It highlights common symptoms of KIS, such as motor and speech delays, intellectual disabilities, and behavioral issues, while also discovering an additional mutational hotspot in the gene involved.
  • The research emphasizes that KIS is characterized by complex channel function alterations, which can aid in molecular diagnosis since clinical features alone are insufficient for identification.
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  • Mazzanti syndrome is a RASopathy linked to Noonan syndrome caused mainly by a specific mutation (c.4A > G, p.Ser2Gly) in the SHOC2 gene, leading to increased MAPK signaling and altered SHOC2 behavior in cells.
  • New research identifies additional pathogenic variants in SHOC2 from six unrelated individuals, showing diverse clinical presentations while still enhancing RAS-MAPK pathway activation.
  • The study broadens the range of recognized SHOC2 mutations, clarifying the disorder’s clinical features and confirming that the disease mechanism involves a gain-of-function effect in SHOC2 activity.
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  • MeCP2 is linked to Rett syndrome and other conditions like autism and intellectual disabilities, but how it causes these diseases is still unclear.
  • Researchers discovered that a protein complex involving TCF20 interacts with MeCP2, and mutations in MeCP2 disrupt this interaction, which can lead to disease.
  • The study also shows that disruptions in the interactions between MeCP2 and the TCF20 complex can result in neurological issues, highlighting their importance for proper brain function.
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Background: Fetal akinesia (FA) results in variable clinical presentations and has been associated with more than 166 different disease loci. However, the underlying molecular cause remains unclear in many individuals. We aimed to further define the set of genes involved.

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