The MYT1L-related neurodevelopmental disorder (MRND) is associated with global motor and language delay, intellectual disability, behavioural disturbances, epilepsy and frequent early-onset obesity. Eating disturbances have been reported but remain poorly characterized. A systematic characterization of the eating behaviour phenotype is essential to improve diagnosis and management. We conducted a multicentre study including 21 French-speaking individuals with a molecularly confirmed MRND and either overweight/obesity or eating behaviour disturbances. Eating behaviours were reported by relatives using validated questionnaires widely employed in rare obesity research: the Dykens Hyperphagia Questionnaire (HQ), the Trousseau Impulsivity Questionnaire, the Children’s Eating Behaviour Questionnaire (CEBQ), the Food Cravings Questionnaire-Trait-reduced (FCQ-T-r, adults only), and a Visual Analogue Scale (VAS) for hunger. When available, questionnaire results were compared with published studies using the same instruments. Persistent hyperphagic behaviours were identified in the majority of patients, with the HQ questionnaire highlighting sustained food-seeking behaviours and pervasive food preoccupation. The mean global score was 25.9, indicating a moderate yet sustained hyperphagic profile. CEBQ revealed a strong attraction to food combined with reduced satiety responsiveness and rapid eating. Hunger was reported as persistent throughout the day. In children food impulsivity was less frequent (5/14; 36

Gabriele-de Vries syndrome (GDVS) is a syndromic form of intellectual disability caused by pathogenic variants in the YY1 gene, which encodes a ubiquitously expressed transcription factor that plays a crucial role in the X-chromosome inactivation (XCI) process. Recent studies have implicated de novo YY1 pathogenic variants in skewed XCI in females with GDVS. Here, we report clinical and molecular features of 11 GDVS patients (ten females), including eight newly identified cases, two being a familial case. Patients exhibited the core phenotype of GDVS but with notable clinical heterogeneity, displaying additional features such as autism spectrum disorder, thyroid dysfunction, hearing impairment, and dysarthria. We also discuss thyroid and other endocrine alterations, autoimmune conditions, and movement disorders in GDVS. Eight YY1 variants were analyzed in silico , exhibiting high pathogenicity scores and predicted structural or functional impact, with most affecting DNA binding or zinc finger domain interactions. Finally, we investigated the XCI patterns of ten female patients, and XCI skewing (moderate or extreme) was detected in blood samples from all of them. Our findings expand the clinical and molecular spectrum of GDVS, in addition to reinforcing a potential involvement of YY1 mutations in modulating XCI patterns in females.

Abnormal expansion of nucleotide repeats was first identified 34 years ago as a unique mutational mechanism. It is now linked to numerous neurogenetic disorders, several of which discovered only recently. The identification of these expansions has led to various classifications based on clinical presentation, repeat nature and genomic location (coding or non-coding regions). Precise diagnosis of these conditions relies on molecular testing, currently performed on a gene-by-gene basis. Their analysis remains challenging, especially for long expansions. We evaluated CRISPR-Cas9-mediated target enrichment coupled to Oxford Nanopore Technologies (ONT) long read sequencing, to accelerate and improve the time-consuming molecular diagnosis of repeat expansion disorders. We simultaneously targeted nine loci involved in 10 repeat expansion disorders in a single capture panel, including FMR1, HTT, DMPK, CNBP/ZNF9, ATXN2, JPH3, FXN, C9ORF72 and RFC1, covering a broad range of repeat types, sizes and diagnostic needs. Results were compared with standard routine testing methods. ONT sequencing using Flongle flow cells yielded results consistent with standard techniques for most loci, particularly for non-complex repeats. However, limitations were observed for structurally complex regions such as RFC1, and inter-run variability required the aggregation of multiple Flongle runs per sample to achieve robust genotyping. These findings highlight both the potential and current limitations of CRISPR-Cas9-enriched ONT sequencing for multiplex diagnosis of repeat expansion disorders in a clinical setting. The approach deserves further development, particularly optimisation of protocols, inclusion of larger sample sizes, and comparison with alternative technologies.

Nuclear factor I (NFI) transcription factors regulate neural stem and progenitor differentiation during brain development. While NFIA, NFIB, and NFIX are linked to neurodevelopmental disorders, the role of NFIC (MIM: 600729) in human disease remains unclear. This study aimed to determine whether NFIC contributes to a neurodevelopmental syndrome, define its phenotype, and assess dosage-dependent effects. We established the first cohort of 11 individuals, including NFIC deletions and single nucleotide variants. Genotype-phenotype correlations, including critical region mapping, were performed. Murine data and bioinformatics were integrated to explore underlying pathomechanisms. We report 11 individuals with NFIC variants, including four with de novo SNVs and seven with deletions encompassing the gene, of whom nine have not been previously reported. A core phenotype of syndromic intellectual disability and macrocephaly was delineated. Opposing cranial phenotypes relative to proximal 19p13.3 duplication cases support a dosage-sensitive effect and a mirror-syndrome model. NFIC-related disorder represents a novel neurodevelopmental syndrome characterized by intellectual disability and macrocephaly, highlighting the importance of NFIC dosage supporting a mirror-syndrome model.

Variants in BRSK2, encoding brain specific kinase-2, have recently been associated with an autosomal dominant neurodevelopmental disorder (NDD). We have assembled 52 cases with heterozygous BRSK2 variants and variable neurodevelopmental phenotypes with frequent neuropsychiatric and behavioral symptoms. The variant spectrum included 15 different truncating variants, seven (potential) splice variants, three structural variants, and 12 different missense variants. Of the missense variants, seven were in the kinase domain, and the others in the UBA and the KA1 domain or outside domains. Variants occurred de novo in 19 cases and were inherited in 18. We utilized Drosophila melanogaster as a model and assessed viability and performed climbing and bang sensitivity assays upon knockdown of the fly orthologue sff or upon overexpression of wildtype or mutant human BRSK2. Pan-neuronal knockdown of sff resulted in impaired locomotor behavior and seizure susceptibility. Ubiquitous or pan-neuronal overexpression of human wildtype BRSK2 in Drosophila resulted in lethality or locomotor impairment, respectively, indicating toxicity. Overexpressing mutant BRSK2 did not or incompletely affect viability and locomotor behavior for six of seven tested kinase domain missense variants and one KA1 domain variant, indicating a (partial) loss-of-function effect. Interestingly, overexpressing BRSK2 with the remaining missense variant from the kinase domain and the two most C-terminal missense variants resulted in possible gain of function. Our findings further delineate the clinical and molecular spectrum of BRSK2-associated NDD and provide further insights into the role of BRSK2/sff in nervous system function and dysfunction.

Congenital heart defects (CHD) are among the most frequent congenital anomalies and represent a significant source of morbidity and mortality in infants. Both genetic and environmental factors are involved, and variants in the MYH6 are potential major genetic factors. The objective of the present study was to describe cardiac phenotypes in individuals with CHD and MYH6 variants. We included individuals with CHD and a MYH6 variant identified in four French genetics laboratories. Clinical and family data were collected. Of the 29 individuals included, 20 (68.9

Fetal pleural effusions can arise in various contexts with different prognosis. They have been reported in fetuses presenting with hereditary or acquired conditions. One particularly rare genetic disorder, known as Knobloch syndrome, seems to emerge as a potential new cause of fetal pleural effusions, associated with severe outcomes. Knobloch syndrome 1 can be caused by biallelic variants in COL18A1. It is primarily characterized by its ophthalmic features, including severe vitreoretinal degeneration with retinal detachment and macular abnormalities. Neurological defects such as encephalocele and developmental delay, along with skeletal and renal malformations, are also associated with the syndrome. The Knobloch syndrome 2 is caused by monoallelic variants in the kinase domain of PAK2. It is less described and seems to also be associated with cardiac and respiratory damage in addition to the Knobloch syndrome 1 phenotype. PAK2 is a ubiquitous protein with a major implication in regulation and remodeling of the cytoskeleton and numerous other cellular pathways. Knobloch-associated variants seem to cause a loss of the kinase function of the protein. Even if the ophthalmic defects are almost constant, PAK2-associated Knobloch syndrome has slightly different features from Knobloch syndrome 1 in which pulmonary and lymphatic damages are still unseen. In a prenatal trio exome sequencing, we identified a novel de novo PAK2 missense variant, NM_002577.4:c.836 A > C, p.(Gln279Pro), classified as likely pathogenic in a 24 weeks of gestation fetus whose only sign was severe bilateral pleural effusion. From a literature review of patients, we recognize this sign as an important antenatal indicator of Knobloch syndrome 2, as it was the first sign identifiable in 2 out of 5 patients. This adds new evidence for the implication of this gene in fetal pleural effusions, with potentially severe outcomes.

Over the past 15 years, molecular methods for human genome analysis have evolved significantly, becoming integral to routine genetic diagnostics. Among various genomic alterations, copy-number variations (CNVs) are particularly important as sources of both benign and pathogenic variants. Accurate assessment of these variants' clinical implications is critical, especially for rare, non-recurrent CNVs and for susceptibility loci linked to neurodevelopmental disorders (NDDs). To address these challenges, the French AchroPuce CNV Interpretation Working Group proposes a novel classification termed "PIEV," referring to CNVs associated with NDDs characterized by incomplete penetrance and variable expressivity. This category complements the existing five-tier ACMG classification system, supporting genetic professionals in harmonizing practice through standardized French national guidelines, thereby enhancing genetic counseling and clinical interpretation precision. Distinguishing clearly pathogenic variants from those with incomplete penetrance is crucial, and the consistent classification of these CNVs independently of the clinical context is essential. Clinical significance assessments should entail collaboration between biologists and multidisciplinary clinical teams, especially in prenatal diagnostics. The working group maintains an annually reviewed curated list of recurrent neurodevelopmental CNVs with reduced penetrance and provides consensus recommendations with a customized interpretation tool to enhance national consistency in CNVs reporting.

Molecular bases of the clinically heterogenous Oculo-Auriculo-Vertebral Spectrum or Craniofacial Microsomia remain largely unknown. Although genetic diagnosis is established in less than 10% of the patients, variants in the FOXI3 gene are the most recurrent genetic cause. We studied a large family with 6 affected individuals on 4 generations showing an autosomal dominant transmission of Oculo-Auriculo-Vertebral Spectrum with incomplete penetrance. The genome sequencing strategy allowed the identification of a new likely pathogenic missense variant located within the Nuclear Localization Signal of FOXI3 and affecting its subcellular localization. Moreover, we described 3 additional rare FOXI3 variants identified in 3 other patients from a cohort of 251 patients with Oculo-Auriculo-Vertebral Spectrum. These variants were classified as Variants of Unknown Significance. In conclusion, this study confirms FOXI3 implication in the Oculo-Auriculo-Vertebral Spectrum and the importance of Nuclear Localization Signal integrity. Genotype-phenotype correlations and putative modifier haplotype are discussed.

Tetralogy of Fallot (TOF) aetiologies remain largely unknown. Although syndromes with genetic cause have been involved, non-syndromic TOF are not completely elucidated, with a genetic diagnosis in less than 20% of the cases. HEY2 is a basic helix-loop-helix (bHLH) repressive transcription factor implicated in cardiac development. In this study, we identify a novel heterozygous missense variant in HEY2 gene segregating within a family presenting with non-syndromic TOF with autosomal dominant transmission. The identified variation c.171 G > C p.(Glu57Asp) was tested through gene reporter assay, revealing a complete disruption of HEY2 repressive activity. These results suggest that HEY2 is a novel gene implicated in the pathogenesis of Tetralogy of Fallot, expanding the genetic spectrum of this congenital heart defect and reinforcing the role of monogenic contributions in non-syndromic TOF.

INTRODUCTION:Decisions concerning nuchal translucency (NT) between 3.0 and 3.4 mm remain controversial, particularly regarding whether to first calculate the combined first trimester screening test or to proceed directly with invasive testing. The literature suggests an increased risk of chromosomal aberration, as well as pathogenic copy number variations (CNVs) on chromosomal microarray, for fetuses with NT between 3.0 and 3.4 mm. The aim of this study was to describe genetic findings of fetuses with NT between 3.0 and 3.4 mm in the first trimester. The secondary objective was to describe ultrasound findings and adverse outcomes for these fetuses. The third objective was to compare genetic, ultrasound findings and adverse outcomes of fetuses with NT between 3.0 and 3.4 mm to those with NT ≥3.5 mm. MATERIAL AND METHODS:We conducted an observational, retrospective study in a referral center between 2017 and 2022. Genetic and ultrasound findings were compared between fetuses with NT between 3.0 and 3.4 mm and those with NT≥3.5 mm. An adverse outcome was defined as one of the following: miscarriage, perinatal death (stillbirth or neonatal death) or termination of pregnancy at parental request, and all major abnormalities or genetic disorders diagnosed before or after delivery. RESULTS:We included 404 fetuses with NT≥3.0 mm who had invasive testing with available karyotype and chromosomal microarray, among whom 20.8% (84/404) had NT between 3.0 and 3.4 mm. The rate of adverse outcomes among fetuses with NT between 3.0 and 3.4 mm was 32.1% (27/84). The rates of chromosomal aberration, pathogenic CNVs, and major ultrasound abnormalities were 16.7% (14/84), 6.0%(5/84), and 9.2% (6/65), respectively, for fetuses with NT between 3.0 and 3.4 mm. In comparison, fetuses with NT greater than 3.5 mm had higher rates of chromosomal aberration and major ultrasound abnormalities, with rates of 47.5% (152/320) and 30.2% (49/162) respectively compared to 16.7% (14/84) and 9.2% (6/65) for fetuses with NT between 3.0 and 3.4 mm (p < 0.001 for both comparisons). However, the rate of pathogenic CNVs was not significantly different between the two groups, with rates of 1.9% (6/320) for NT≥3.5 mm and 6.0% (5/84) for NT between 3.0 and 3.4 mm (p = 0.06). CONCLUSIONS:The rate of chromosomal aberration and pathogenic CNVs on chromosomal microarray is high among fetuses with NT between 3.0 and 3.4 mm, although these rates remain lower than those observed among fetuses with NT≥3.5 mm.

Titin truncating variants (TTNtv) are the main genetic cause of dilated cardiomyopathies (DCMs). The phenotype and prognosis of probands have been evaluated in several large cohorts. However, few data are available on intrafamilial expressivity. To evaluate the phenotypical variability, we selected probands and family members carrying a unique TTN variant and recorded cardiac and genetic information. The cohort included 332 probands (314 TTNtv probands and 18 probands with in silico predicted in-frame exon skipping probands) and 191 relatives of TTNtv probands including 98 affected family members. Within TTNtv families, 96% of the affected relatives presented the same cardiomyopathy subtype as the proband, and 60% shared severity criteria (heart transplantation, implantable cardioverter-defibrillator, personal sudden death). Furthermore, we reported 18 probands that carry predicted in-frame exon skipping variants; they presented DCM (84%) as TTNtv patients but lower rate of rhythm disorders (0% vs. 29% respectively). In this work, we extend the genetic spectrum of TTNtv associated with DCM and show that within a family, and the cardiomyopathy phenotype is homogenous but the expressivity could vary. Such results are helpful for appropriate genetic counseling to better predict and manage the phenotype of mutation carriers.

To date, only one study describes three unrelated cases of neurodevelopmental disorders associated with duplications in 22q13.2, which include the TCF20 gene. In contrast, TCF20 variants and deletions are well characterized. Here, we report six new cases of 22q13.2 gain, including TCF20, identified through array-comparative genomic hybridization (array-CGH). Probands exhibited neurodevelopmental delay, and several presented with facial dysmorphism, abnormal growth parameters, and abnormalities affecting the skeletal, respiratory, genitourinary, and/or cardiovascular systems. We documented one 440 Kb triplication and five cases of duplication ranging from 82.5 Kb to 3.03 Mb in size. Co-segregation analysis of the CNV and clinical symptoms supports variable expressivity. However, the complete penetrance of these gains remains questionable compared to the known pathogenic variants and structural variations associated with loss of function. We discuss the genotype-phenotype correlations and hypotheses surrounding the impairment of TCF20 protein function.

BACKGROUND AND AIMS:Truncating variants in the TTN gene (TTNtv) are the most common genetic cause of dilated cardiomyopathy (DCM) but also occur as incidental findings in the general population. This study investigated factors associated with the clinical manifestation of TTNtv. METHODS:An international multicentre retrospective observational study was performed in families with TTNtv-related DCM. Shared frailty models were used to estimate associations of variant characteristics with lifetime risk of DCM, and logistic regression to estimate odds ratios (ORs) for individual-level clinical risk factor profiles (cardiac conditions, cardiovascular comorbidities, lifestyle) and DCM. RESULTS:A total of 3158 subjects in 1043 families with TTNtv-related DCM were studied. TTNtv-positive subjects were 21-fold more likely to develop DCM [OR, 21.21; 95% confidence interval (CI), 14.80-30.39]. Disease onset was earlier in males, but was similar for TTNtv of different types and locations. The presence of clinical risk factors was associated with earlier DCM onset (OR, 3.41; 95% CI, 2.06-5.64), with a prior history of atrial fibrillation having a two-fold increased odds of DCM (OR, 2.05; 95% CI, 1.27-3.32). The prevalence of clinical risk factors increased with age; however, the strength of the DCM association was greatest for young-onset (<30 years) disease (OR, 4.75; 95% CI, 2.35-9.60). Administration of beta-adrenergic receptor or renin-angiotensin system-blocking drugs prior to overt DCM was associated with 87% reduced odds of DCM (OR, .13; 95% CI, .08-.23). CONCLUSIONS:Disease onset in TTNtv-associated familial DCM is dependent on individual patient context and is potentially modifiable by risk factor management and prophylactic therapeutic intervention.

In 30-40% of fetuses with structural defects, the causal variant remains undiagnosed after karyotype, chromosomal microarray, and exome sequencing. This study presents the results of a reanalysis of unsolved prenatal ES (pES) cases and investigates how postnatal/postmortem phenotyping contributes to identifying relevant variants. pES data was prospectively reanalyzed for unsolved cases enrolled in the AnDDI-Prénatome cohort study. Postnatal/postmortem data were included with prenatal features using Human Phenotype Ontology terms up to 3 years after pES. The reanalysis involved updating bioinformatic processing and querying raw data using a GREP query. We reanalyzed 58/94 (62%) unsolved pES cases, including 8 variants of unknown significance. Data for clinical examination at birth was available for all live newborns, and postmortem examination was available in 12 terminated fetuses. Additional features were identified at birth in 27/58 cases (44%): 9 terminated fetuses, 2 stillbirths, and 16 live newborns. One diagnosis (SNAPC4) was obtained through a periodic query following recent associations with human disease, and without additional clinical data. Three additional VUS were identified through reanalysis with the addition of new clinical features, illustrating the limited contribution of updated postnatal/postmortem phenotyping in identifying relevant variants after negative pES. In conclusion, the benefit of prospective reanalysis of unsolved pES is limited, even over time. Postnatal genome sequencing may be a more appropriate option than reanalysis with postnatal/postmortem phenotyping to establish a causal diagnosis.

Background FLNA loss of function manifests across a broad spectrum of phenotypes, ranging from severe prenatal onset to asymptomatic cases. Bilateral periventricular nodular heterotopia (BPNH) consistently occurs in affected individuals. This retrospective study involving French patients with BPNH evaluates the prevalence of FLNA gene dosage anomalies and investigates genotype-phenotype correlations in a large cohort of French patients with BPNH.Methods A retrospective observational study was conducted on 391 individuals diagnosed with BPNH confirmed by brain MRI. Sequencing analysis using Sanger or next-generation sequencing was complemented by targeted array-comparative genomic hybridisation to identify copy number variants (CNVs).Results FLNA variants were identified in 40% of females and 12% of males. Among these, 87% were single nucleotide variants (SNVs), while CNVs accounted for 13%, all of which were deletions. Half of the CNVs involved a recurrent deletion spanning exons 31-48, often accompanied by a duplication of the neighbouring EMD gene. This del-dup was associated with a milder phenotype, whereas smaller de novo deletions correlated with severe outcomes. Mosaicism was also detected in three cases.Conclusion FLNA CNV analysis, particularly for recurrent deletions and mosaicism, is essential in the genetic evaluation of BPNH. Integrating CNV detection with SNV analysis improves diagnostic accuracy and enhances understanding of genotype-phenotype correlations.

BACKGROUND SCN5A variants are associated with a spectrum of cardiac electrical disorders with clear phenotypes. However, they may also be associated with complex phenotypic traits like overlap syndromes or pleiotropy, which have not been systematically described. In addition, the involvement of SCN5A in dilated cardiomyopathies (DCMs) remains controversial. OBJECTIVE We aimed to evaluate the different phenotypes associated with pathogenic (P)/likely pathogenic (LP) SCN5A variants and to determine the prevalence of pleiotropy in a large multicentric cohort of P/LP SCN5A variant carriers. METHODS The DNA of 13,510 consecutive probands (9960 with cardiomyopathies) was sequenced with a custom panel of genes. Individuals carrying a heterozygous single P/LP SCN5A variant were selected and phenotyped. RESULTS The study included 170 P/LP variants found in 495 patients. Of them, 119 (70%) were exclusively associated with a single well-established phenotype: 91 with Brugada syndrome, 15 with type 3 long QT syndrome, 6 with progressive cardiac conduction disease, 4 with multifocal ectopic Purkinje-related premature contractions, and 3 with sick sinus syndrome. Thirtytwo variants (19%) were associated with overlap syndromes or pleiotropy. The 19 remaining variants (11%) were associated with atypical or unclear phenotypes. Of those, 8 were carried by 8 patients presenting with DCM with a debatable causative genotype/phenotype link. CONCLUSION Most P/LP SCN5A variants were found in patients with primary electrical disorders, mainly Brugada syndrome. Nearly 20% were associated with overlap syndromes or pleiotropy, underscoring the need for comprehensive phenotypic evaluation. The concept of SCN5A variants causing DCM is extremely rare (8/9960) if not questionable.