Publications by authors named "Willems Marjolaine"

Pigmentation is orchestrated by hundreds of genes involved in cellular functions going from early developmental fate of pigment cells to melanin synthesis. The Two Pore Channel 2 (TPC2) a Ca2+ and Na+ channel acidifies melanosomal pH and thus inhibits pigmentation. A young patient was recently reported with generalized hypopigmentation but uneventful ocular examination, caused by the de novo heterozygous TPCN2 variant c.

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Background: Aarskog-Scott syndrome (AAS) is a rare condition with multiple congenital anomalies, caused by hemizygote variants in the gene. Its description was based mostly on old case reports, in whom a molecular diagnosis was not always available, or on small series. The aim of this study was to better delineate the phenotype and the natural history of AAS and to provide clues for the diagnosis and the management of the patients.

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  • - Microtubule affinity-regulating kinase 2 (MARK2) is crucial for neurons to develop properly, and variants in MARK2 have been linked to autism spectrum disorder (ASD) and other neurodevelopmental issues, with most being loss-of-function mutations.
  • - A study analyzed 31 individuals with MARK2 variants showing ASD along with unique facial features, finding that the loss of MARK2 disrupts early neuron development and leads to abnormal growth patterns in neural cells.
  • - Research using iPSC models and MARK2-deficient mice highlighted the link between MARK2 loss and issues in neuronal function, connecting it to the reduction of the WNT/β-catenin signaling pathway, while suggesting lithium as a potential treatment
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Alazami syndrome is an autosomal recessive disease characterized by global developmental delay, growth restriction, and distinctive facial features. Fewer than 50 individuals are currently reported with biallelic loss of function variants in LARP7. We report the case of a 3.

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DDX17 is an RNA helicase shown to be involved in critical processes during the early phases of neuronal differentiation. Globally, we compiled a case-series of 11 patients with neurodevelopmental phenotypes harbouring de novo monoallelic variants in DDX17. All 11 patients in our case series had a neurodevelopmental phenotype, whereby intellectual disability, delayed speech and language, and motor delay predominated.

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Objective: To analyze the lymphocyte subsets in individuals with Kabuki syndrome for better characterizing the immunological phenotype of this rare congenital disorder.

Methods: We characterized the immunological profile including B-, T- and natural killer-cell subsets in a series (N = 18) of individuals with Kabuki syndrome.

Results: All 18 individuals underwent genetic analysis: 15 had a variant in KMT2D and 3 a variant in KDM6A.

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Article Synopsis
  • Pathogenic variants in a specific gene lead to an autosomal dominant syndrome characterized by developmental delays and heart issues.
  • The study focused on two variants near the splice site of exon 7, which were predicted to either skip exon 7 or activate an alternative splice site, affecting protein function.
  • RNA analysis confirmed these variants led to intron retention, causing a frameshift and early termination of protein translation, emphasizing the need for both predictive and experimental methods to understand genetic variants' impacts.
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Purpose: Valproic acid or valproate is an effective antiepileptic drug; however, embryonic exposure to valproate can result in a teratogenic disorder referred to as fetal valproate syndrome (OMIM #609442). Currently there are no diagnostic biomarkers for the condition. This study aims to define an episignature biomarker for teratogenic antenatal exposure to valproate.

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  • Tatton-Brown-Rahman syndrome (TBRS) is a genetic disorder characterized by overgrowth, intellectual disability, and distinct facial features, resulting from mutations in a gene that regulates DNA methylation.* -
  • A study of 24 French patients identified 17 new genetic variants, confirming that 100% showed intellectual disability, 96% had distinctive facial traits, and 87% exhibited overgrowth, alongside novel symptoms like hypertrichosis.* -
  • The findings enhance the understanding of TBRS's clinical presentation, aiding in diagnosis and patient care by clarifying its genetic and phenotypic diversity.*
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Chung-Jansen syndrome is a neurodevelopmental disorder characterized by intellectual disability, behavioral problems, obesity and dysmorphic features. It is caused by pathogenic variants in the PHIP gene that encodes for the Pleckstrin homology domain-interacting protein, which is part of an epigenetic modifier protein complex. Therefore, we hypothesized that PHIP haploinsufficiency may impact genome-wide DNA methylation (DNAm).

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  • * A study analyzed immune cells from 41 male Fabry patients and 20 controls, revealing that FD patients show higher expression of specific markers (CD27 and CD28) in certain T cells, which correlates with the levels of harmful lipids (lysoGb3 and Gb3) in the blood.
  • * Treatment with agalsidase beta was found to increase Natural Killer cell proportions, suggesting potential new biomarker correlations that could enhance understanding and management of Fabry disease.
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  • The study aimed to clarify the dermatological features of Costello syndrome (CS) and distinguish them from other similar syndromes like cardiofaciocutaneous syndrome (CFCS) and types of Noonan syndrome (NS).
  • A ten-year multi-center study involving 31 patients found common skin and hair anomalies in CS, such as excessive eyebrows and various types of skin growths, which can help differentiate CS from CFCS and NS.
  • The findings propose multiple melanocytic naevi as a potential marker for a milder form of CS and suggest that acitretin could be beneficial for treating certain skin conditions, although no clear genotype-phenotype link was identified.
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  • The translation elongation factor eEF1A2 is crucial for binding aminoacyl-tRNA to the ribosome, and since 2012, 21 harmful variants have been linked to severe neurodevelopmental disorders, including epilepsy and intellectual disabilities.
  • A recent study gathered 26 patients with EEF1A2 variants, revealing a milder clinical profile than previously reported, with higher walking and language skills and lower rates of intellectual disability and epilepsy.
  • The research identified 8 new EEF1A2 variants and suggests that severe and moderate phenotypes are linked to specific protein regions affecting GTP exchange, while milder variants may affect secondary functions, contributing to a broader understanding
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  • The study analyzes data from two groups of individuals with DDX3X variations, one from physicians (48 individuals) and the other from caregivers (44 individuals).
  • The results reveal shared symptoms between the two groups, including previously unreported early childhood issues like feeding difficulties and delayed developmental milestones.
  • The discussion emphasizes that both datasets complement each other, highlighting the importance of addressing symptoms such as ADHD, anxiety, and sleep disturbances in affected individuals.
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  • The study aims to create a new AI-based model for identifying Kabuki Syndrome (KS) from 2D facial photos, differentiating between its two types: KS1 (KMT2D-related) and KS2 (KDM6A-related).
  • Utilizing over 1,400 facial images from 634 patients and controls, researchers incorporated machine learning techniques, specifically XGboost, for improved predictive accuracy.
  • The proposed model achieved an impressive accuracy of 95.8% in identifying KS and showed better performance than existing AI solutions and expert evaluations.
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Objective: To evaluate the postnatal outcome of children with antenatal colonic hyperechogenicity, currently considered as a sign of lysinuria-cystinuria, but which may also be a sign of other disorders with a more severe prognosis.

Method: We carried out a French multi-centric retrospective study via 15 Multidisciplinary Center for Prenatal Diagnosis from January 2011 to January 2021. We included pregnancies for which fetal colonic hyperechogenicity had been demonstrated.

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  • - Cat Eye Syndrome (CES) is a rare genetic disorder linked to a marker chromosome from chromosome 22, leading to diverse symptoms including iris coloboma, anal atresia, and preauricular tags, but these are present in less than half of the cases.
  • - An international study of 43 CES patients found that only 16% displayed all three classic symptoms, while 9% showed none; additional issues such as cardiac anomalies (51%) and intellectual disabilities (47%) were also common.
  • - The study highlights the significance of supernumerary marker chromosomes (sSMC), found in 91% of cases, with many parents showing mild traits, emphasizing the need for genetic counseling regarding recurrence risks.
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Background: The mechanisms determining the laterality and the rotation direction of hair whorls are unknown. Here we report observations on twins investigating the genetic bases of whorl pattern formation. Knowing that vortex phenomena may depend on geographic effects, we also provide comparative data on whorls from children born in the Northern hemisphere (France) versus children born in the Southern hemisphere (Chile).

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Purpose: BCL11B-related disorder (BCL11B-RD) arises from rare genetic variants within the BCL11B gene, resulting in a distinctive clinical spectrum encompassing syndromic neurodevelopmental disorder, with or without intellectual disability, associated with facial features and impaired immune function. This study presents an in-depth clinico-biological analysis of 20 newly reported individuals with BCL11B-RD, coupled with a characterization of genome-wide DNA methylation patterns of this genetic condition.

Methods: Through an international collaboration, clinical and molecular data from 20 individuals were systematically gathered, and a comparative analysis was conducted between this series and existing literature.

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  • DYRK1A Syndrome is caused by mutations in the DYRK1A gene, leading to global developmental delays, intellectual disability, and common physical issues like low birth weight and microcephaly.
  • The study compiled growth data from 92 individuals with the syndrome, utilizing various sources including pediatric records and scientific literature.
  • New growth charts were created for key measurements (height, weight, BMI, occipitofrontal circumference) for children aged 0-5 years, providing a useful tool for managing patients with DYRK1A Syndrome.
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Introduction: Mandibulo-Facial Dysostosis with Microcephaly (MFDM) is a rare disease with a broad spectrum of symptoms, characterized by zygomatic and mandibular hypoplasia, microcephaly, and ear abnormalities. Here, we aimed at describing the external ear phenotype of MFDM patients, and train an Artificial Intelligence (AI)-based model to differentiate MFDM ears from non-syndromic control ears (binary classification), and from ears of the main differential diagnoses of this condition (multi-class classification): Treacher Collins (TC), Nager (NAFD) and CHARGE syndromes.

Methods: The training set contained 1,592 ear photographs, corresponding to 550 patients.

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  • - The study investigates the increasing frequency of multiple molecular diagnoses (MMDs) in individuals with congenital anomalies/intellectual disability (CA/ID) through clinical exome/genome sequencing, highlighting rates between 1.8% to 7.1% previously documented.
  • - Out of 880 positive exome sequencing diagnoses analyzed from 2014 to 2021, MMDs were found in 3.5% of cases, with additional potential MMDs identified in 4.4% of individuals, indicating their significance in disease comprehension.
  • - Emphasizing the necessity for reanalysis of sequencing data and collaboration among clinicians and biologists, the study underlines the importance of updated clinical information and enhanced bio
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