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Cells rely on a diverse repertoire of genes for maintaining homeostasis, but the transcriptional networks underlying their expression remain poorly understood. The MOF acetyltransferase-containing Non-Specific Lethal (NSL) complex is a broad transcription regulator. It is essential in Drosophila, and haploinsufficiency of the human KANSL1 subunit results in the Koolen-de Vries syndrome. Here, we perform a genome-wide RNAi screen and identify the BET protein BRD4 as an evolutionary conserved co-factor of the NSL complex. Using Drosophila and mouse embryonic stem cells, we characterise a recruitment hierarchy, where NSL-deposited histone acetylation enables BRD4 recruitment for transcription of constitutively active genes. Transcriptome analyses in Koolen-de Vries patient-derived fibroblasts reveals perturbations with a cellular homeostasis signature that are evoked by the NSL complex/BRD4 axis. We propose that BRD4 represents a conserved bridge between the NSL complex and transcription activation, and provide a new perspective in the understanding of their functions in healthy and diseased states. The MOF acetyltransferase-containing Non-Specific Lethal (NSL) complex is a broad transcription regulator and haploinsufficiency of its KANSL1 subunit results in the Koolen-de Vries syndrome in humans. Here, the authors identify the BET protein BRD4 as evolutionary conserved co-factor of the NSL complex and provide evidence that NSL-deposited histone acetylation induces BRD4 recruitment for transcription of constitutively active genes.

Although recurrent infections in Rubinstein–Taybi syndrome (RSTS) are common, and probably multifactorial, immunological abnormalities have not been extensively described with only isolated cases or small case series of immune deficiency and dysregulation having been reported. The objective of this study was to investigate primary immunodeficiency (PID) and immune dysregulation in an international cohort of patients with RSTS. All published cases of RSTS were identified. The corresponding authors and researchers involved in the diagnosis of inborn errors of immunity or genetic syndromes were contacted to obtain up-to-date clinical and immunological information. Ninety-seven RSTS patients were identified. For 45 patients, we retrieved data from the published reports while for 52 patients, a clinical update was provided. Recurrent or severe infections, autoimmune/autoinflammatory complications, and lymphoproliferation were observed in 72.1%, 12.3%, and 8.2% of patients. Syndromic immunodeficiency was diagnosed in 46.4% of individuals. Despite the broad heterogeneity of immunodeficiency disorders, antibody defects were observed in 11.3% of subjects. In particular, these patients presented hypogammaglobulinemia associated with low B cell counts and reduction of switched memory B cell numbers. Immunoglobulin replacement therapy, antibiotic prophylaxis, and immunosuppressive treatment were employed in 16.4%, 8.2%, and 9.8% of patients, respectively. Manifestations of immune dysfunctions, affecting mostly B cells, are more common than previously recognized in patients with RSTS. Full immunological assessment is warranted in these patients, who may require detailed investigation and specific supportive treatment.

SLITRK2 is a single-pass transmembrane protein expressed at postsynaptic neurons that regulates neurite outgrowth and excitatory synapse maintenance. In the present study, we report on rare variants (one nonsense and six missense variants) in SLITRK2 on the X chromosome identified by exome sequencing in individuals with neurodevelopmental disorders. Functional studies showed that some variants displayed impaired membrane transport and impaired excitatory synapse-promoting effects. Strikingly, these variations abolished the ability of SLITRK2 wild-type to reduce the levels of the receptor tyrosine kinase TrkB in neurons. Moreover, Slitrk2 conditional knockout mice exhibited impaired long-term memory and abnormal gait, recapitulating a subset of clinical features of patients with SLITRK2 variants. Furthermore, impaired excitatory synapse maintenance induced by hippocampal CA1-specific cKO of Slitrk2 caused abnormalities in spatial reference memory. Collectively, these data suggest that SLITRK2 is involved in X-linked neurodevelopmental disorders that are caused by perturbation of diverse facets of SLITRK2 function. The protein SLITRK2 plays an important role in synaptic communication. This study identifies X-linked SLITRK2 variants that underlie neurodevelopmental disorders by impairing excitatory synapses.

SETBP1 haploinsufficiency disorder (MIM#616078) is caused by haploinsufficiency of SETBP1 on chromosome 18q12.3, but there has not yet been any systematic evaluation of the major features of this monogenic syndrome, assessing penetrance and expressivity. We describe the first comprehensive study to delineate the associated clinical phenotype, with findings from 34 individuals, including 24 novel cases, all of whom have a SETBP1 loss-of-function variant or single (coding) gene deletion, confirmed by molecular diagnostics. The most commonly reported clinical features included mild motor developmental delay, speech impairment, intellectual disability, hypotonia, vision impairment, attention/concentration deficits, and hyperactivity. Although there is a mild overlap in certain facial features, the disorder does not lead to a distinctive recognizable facial gestalt. As well as providing insight into the clinical spectrum of SETBP1 haploinsufficiency disorder, this reports puts forward care recommendations for patient management.

Zhu–Tokita–Takenouchi–Kim (ZTTK) syndrome, an intellectual disability syndrome first described in 2016, is caused by heterozygous loss-of-function variants in SON. Its encoded protein promotes pre-mRNA splicing of many genes essential for development. Whereas individual phenotypic traits have previously been linked to erroneous splicing of SON target genes, the phenotypic spectrum and the pathogenicity of missense variants have not been further evaluated. We present the phenotypic abnormalities in 52 individuals, including 17 individuals who have not been reported before. In total, loss-of-function variants were detected in 49 individuals (de novo in 47, inheritance unknown in 2), and in 3, a missense variant was observed (2 de novo, 1 inheritance unknown). Phenotypic abnormalities, systematically collected and analyzed in Human Phenotype Ontology, were found in all organ systems. Significant inter-individual phenotypic variability was observed, even in individuals with the same recurrent variant (n = 13). SON haploinsufficiency was previously shown to lead to downregulation of downstream genes, contributing to specific phenotypic features. Similar functional analysis for one missense variant, however, suggests a different mechanism than for heterozygous loss-of-function. Although small in numbers and while pathogenicity of these variants is not certain, these data allow for speculation whether de novo missense variants cause ZTTK syndrome via another mechanism, or a separate overlapping syndrome. In conclusion, heterozygous loss-of-function variants in SON define a recognizable syndrome, ZTTK, associated with a broad, severe phenotypic spectrum, characterized by a large inter-individual variability. These observations provide essential information for affected individuals, parents, and healthcare professionals to ensure appropriate clinical management.

BackgroundSATB2-associated syndrome (SAS) results from various mutations of the SATB2 gene and associates a neurodevelopmental disorder including major speech delay, intellectual disability, and behavioral problems with dental anomalies, sometimes a cleft palate, risk of osteoporosis, and facial dysmorphism. The principal objective of this study was to describe the oral phenotype of young children with SATB2-associated syndrome, especially in terms of orofacial malformation of Robin Sequence (RS) spectrum (bifid uvula, cleft palate, or RS, dental malformation, feeding and communication, with data from a national cohort. The secondary objective was to determine whether feeding and communication disorders were more severe when associated with an orofacial malformation of RS spectrum.MethodsWe conducted a retrospective cross-sectional study among the largest possible cohort of patients with a mutation of the SATB2 gene in France. A questionnaire completed by the referring physicians and by telephone with parents enabled us to collect the following clinical information: (1) orofacial morphology, feeding difficulties, and pharyngeal functioning from birth to 3 years, (2) communication and language from 0 to 6 years, (3) speech development at the last examination.ResultsThe study included 40 patients. Early and persistent feeding difficulties were found in 55% of the children. Communication was abnormal from the first months of life, with poor babbling in 85% of them. A major language delay was described in all patients; 65% had a vocabulary of 10 words or less. An anomaly of RS spectrum was found in half the cases, and dental malformations were described in 90%. Feeding difficulties and language delay were greater in the group with one or more orofacial malformations than the group with none.ConclusionThis study confirmed the severity of oral involvement, affecting feeding and speech simultaneously, in individuals with SAS. It raises the question of why the oral phenotype involving feeding and speech is more severe in the presence of cleft palate or RS. We recommend close monitoring of prelanguage communication in infants with apparently isolated cleft palate or RS and the search for SATB2 impairment when a cleft palate or RS is found, especially in the prenatal period.

Background Until very recently, preconception genetic testing was only conducted in particular communities, ethnic groups or families for which an increased risk of genetic disease was identified. To detect in general population a risk for a couple to have a child affected by a rare, recessive or X-linked, genetic disease, carrier screening is proposed in several countries. We aimed to determine the current public opinion relative to this approach in France, using either a printed or web-based questionnaire. Results Among the 1568 participants, 91% are favorable to preconception genetic tests and 57% declare to be willing to have the screening if the latter is available. A medical prescription by a family doctor or a gynecologist would be the best way to propose the test for 73%, with a reimbursement from the social security insurance. However, 19% declare not to be willing to use the test because of their ethic or moral convictions, and the fear that the outcome would question the pregnancy. Otherwise, most participants consider that the test is a medical progress despite the risk of an increased medicalization of the pregnancy. Conclusion This first study in France highlights a global favorable opinion for the preconception genetic carrier testing under a medical prescription and a reimbursement by social security insurance. Our results emphasize as well the complex concerns underpinned by the use of this screening strategy. Therefore, the ethical issues related to these tests include the risk of eugenic drift mentioned by more than half of the participants.

Microtubules are essential components of the neuronal cytoskeleton. The - and -tubulins, variably expressed in the central nervous system, play key roles in neurogenesis and brain development. Pathogenic variants in have recently been identified as an ultra-rare cause of pediatric neurodevelopmental disorders (NDDs). However, the neurological and behavioral manifestations, genotype-phenotype correlations, and underlying disease mechanisms remain poorly understood due to the limited number of reported families. We describe a cohort of families presenting with microcephaly, global developmental delay, speech impairment, seizures and/or EEG abnormalities, movement disorders and severe behavioral disorders. Clinical assessments and brain imaging studies were conducted over a 10-year follow-up period. Genetic analysis was performed via whole-exome sequencing (WES), and structural modeling was used to investigate the functional impact of the identified variants. WES revealed a novel recurrent heterozygous pathogenic variant in (NM_001069.3:c.1172G > A; NP_001060.1:p.Arg391His), identified as the cause of disease in multiple affected individuals from unrelated families. Comparative analysis with previously reported variants confirmed that this novel recurrent mutation affects a highly conserved Arg391 residue within the longitudinal E-site heterodimer interface. Computational modeling demonstrated that the variant disrupts / -tubulin heterodimer formation, impairing binding stability at this critical interaction site. Our findings expand the phenotypic and genotypic spectrum of -related disorders and identify Arg391 as a mutational hotspot linked to severe brain developmental disorders due to aberrant tubulin dynamics, highlighting the disruption of the / -tubulin heterodimer formation as the disease mechanism associated to this novel hotspot variant. These results provide new insights into disease mechanisms and offer a foundation for potential future therapeutic approaches aimed at stabilizing / -tubulin interactions.

X-linked dominant chondrodysplasia punctata (CDPX2 or Conradi-Hünermann-Happle syndrome, MIM #302960) is caused by mutations in the EBP gene. Affected female patients present with Blaschkolinear ichthyosis, coarse hair or alopecia, short stature, and normal psychomotor development. The disease is usually lethal in boys. Nevertheless, few male patients have been reported; they carry a somatic mosaicism in EBP or present with Klinefelter syndrome. Here, we report CDPX2 patients belonging to a three-generation family, carrying the splice variant c.301 + 5 G > C in intron 2 of EBP. The grandfather carries the variant as mosaic state and presents with short stature and mild ichthyosis. The mother also presents with short stature and mild ichthyosis and the female fetus with severe limb and vertebrae abnormalities and no skin lesions, with random X inactivation in both. This further characterizes the phenotypical spectrum of CDPX2, as well as intrafamilial variability, and raises the question of differential EBP mRNA splicing between the different target tissues.