ARID1A-BAF coordinates ZIC2 genomic occupancy for epithelial-to-mesenchymal transition in cranial neural crest specification.

The BAF chromatin remodeler regulates lineage commitment including cranial neural crest cell (CNCC) specification. Variants in BAF subunits cause Coffin-Siris syndrome (CSS), a congenital disorder characterized by coarse craniofacial features and intellectual disability. Approximately 50% of individuals with CSS harbor variants in one of the mutually exclusive BAF subunits, ARID1A/ARID1B. While Arid1a deletion in mouse neural crest causes severe craniofacial phenotypes, little is known about the role of ARID1A in CNCC specification. Using CSS-patient-derived ARID1A+/- induced pluripotent stem cells to model CNCC specification, we discovered that ARID1A-haploinsufficiency impairs epithelial-to-mesenchymal transition (EMT), a process necessary for CNCC delamination and migration from the neural tube. Furthermore, wild-type ARID1A-BAF regulates enhancers associated with EMT genes. ARID1A-BAF binding at these enhancers is impaired in heterozygotes while binding at promoters is unaffected. At the sequence level, these EMT enhancers contain binding motifs for ZIC2, and ZIC2 binding at these sites is ARID1A-dependent. When excluded from EMT enhancers, ZIC2 relocates to neuronal enhancers, triggering aberrant neuronal gene activation. In mice, deletion of Zic2 impairs NCC delamination, while ZIC2 overexpression in chick embryos at post-migratory neural crest stages elicits ectopic delamination from the neural tube. These findings reveal an essential ARID1A-ZIC2 axis essential for EMT and CNCC delamination.

The missing link: ARID1B non-truncating variants causing Coffin-Siris syndrome due to protein aggregation.

ARID1B is the most frequently mutated gene in Coffin-Siris syndrome (CSS). To date, the vast majority of causative variants reported in ARID1B are truncating, leading to nonsense-mediated mRNA decay. In the absence of experimental data, only few ARID1B amino acid substitutions have been classified as pathogenic, mainly based on clinical data and their de novo occurrence, while most others are currently interpreted as variants of unknown significance. The present study substantiates the pathogenesis of ARID1B non-truncating/NMD-escaping variants located in the SMARCA4-interacting EHD2 and DNA-binding ARID domains. Overexpression assays in cell lines revealed that the majority of EHD2 variants lead to protein misfolding and formation of cytoplasmic aggresomes surrounded by vimentin cage-like structures and co-localizing with the microtubule organisation center. ARID domain variants exhibited not only aggresomes, but also nuclear aggregates, demonstrating robust pathological effects. Protein levels were not compromised, as shown by quantitative western blot analysis. In silico structural analysis predicted the exposure of amylogenic segments in both domains due to the nearby variants, likely causing this aggregation. Genome-wide transcriptome and methylation analysis in affected individuals revealed expression and methylome patterns consistent with those of the pathogenic haploinsufficiency ARID1B alterations in CSS cases. These results further support pathogenicity and indicate two approaches for disambiguation of such variants in everyday practice. The few affected individuals harbouring EHD2 non-truncating variants described to date exhibit mild CSS clinical traits. In summary, this study paves the way for the re-evaluation of previously unclear ARID1B non-truncating variants and opens a new era in CSS genetic diagnosis.

Delineation of the adult phenotype of Coffin-Siris syndrome in 35 individuals.

Coffin-Siris syndrome (CSS) is a rare multisystemic autosomal dominant disorder. Since 2012, alterations in genes of the SWI/SNF complex were identified as the molecular basis of CSS, studying largely pediatric cohorts. Therefore, there is a lack of information on the phenotype in adulthood, particularly on the clinical outcome in adulthood and associated risks. In an international collaborative effort, data from 35 individuals ≥ 18 years with a molecularly ascertained CSS diagnosis (variants in ARID1B, ARID2, SMARCA4, SMARCB1, SMARCC2, SMARCE1, SOX11, BICRA) using a comprehensive questionnaire was collected. Our results indicate that overweight and obesity are frequent in adults with CSS. Visual impairment, scoliosis, and behavioral anomalies are more prevalent than in published pediatric or mixed cohorts. Cognitive outcomes range from profound intellectual disability (ID) to low normal IQ, with most individuals having moderate ID. The present study describes the first exclusively adult cohort of CSS individuals. We were able to delineate some features of CSS that develop over time and have therefore been underrepresented in previously reported largely pediatric cohorts, and provide recommendations for follow-up.

Biallelic OTUD6B variants associated with a Kabuki syndrome-like disorder in three siblings: A clinical report and literature review.

Biallelic variants in the OTUD6B gene have been reported in the literature in association with an intellectual developmental disorder featuring dysmorphic facies, seizures, and distal limb abnormalities. Physical differences described for affected individuals suggest that the disorder may be clinically recognizable, but previous publications have reported an initial clinical suspicion for Kabuki syndrome (KS) in some affected individuals. Here, we report on three siblings with biallelic variants in OTUD6B co-segregating with neurodevelopmental delay, shared physical differences, and other clinical findings similar to those of previously reported individuals. However, clinical manifestations such as long palpebral fissures, prominent and cupped ears, developmental delay, growth deficiency, persistent fetal fingertip pads, vertebral anomaly, and seizures in the proband were initially suggestive of KS. In addition, previously unreported clinical manifestations such as delayed eruption of primary dentition, soft doughy skin with reduced sweating, and mirror movements present in our patients suggest an expansion of the phenotype, and we perform a literature review to update on current information related to OTUD6B and human gene-disease association.

ARID2, a milder cause of Coffin-Siris Syndrome? Broadening the phenotype with 17 additional individuals.

Coffin-Siris Syndrome (CSS, MIM 135900) is now a well-described genetic condition caused by pathogenic variants in the Bromocriptine activating factor (BAF) complex, including ARID1B, ARID1A, ARID2, SMARCA4, SMARCE1, SMARCB1, SOX11, SMARCC2, DPF2, and more recently, BICRA. Individuals with CSS have a spectrum of various medical challenges, most often evident at birth, including feeding difficulties, hypotonia, organ-system anomalies, and learning and developmental differences. The classic finding of fifth digit hypo- or aplasia is seen variably. ARID2, previously described, is one of the less frequently observed gene changes in CSS. Although individuals with ARID2 have been reported to have classic features of CSS including hypertrichosis, coarse facial features, short stature, and fifth digit anomalies, as with many of the other CSS genes, there appears to be a spectrum of phenotypes. We report here a cohort of 17 individuals with ARID2 variants from the Coffin-Siris/BAF clinical registry and detail their medical challenges as well as developmental progress. Feeding difficulties, hypotonia, and short stature occur often, and hip dysplasia appears to occur more often than with other genes, however more severe medical challenges such as significant brain and cardiac malformations are rarer. Individuals appear to have mild to moderate intellectual impairment and may carry additional diagnoses such as ADHD. Further phenotypic description of this gene will aid clinicians caring for individuals with this rarer form of CSS.

Identification of a novel phenotype of external ear deformity related to Coffin-Siris syndrome-9 and literature review.

De novo germline variants of the SRY-related HMG-box 11 gene (SOX11) have been reported to cause Coffin-Siris syndrome-9 (CSS-9), a rare congenital disorder associated with multiple organ malformations, including ear anomalies. Previous clinical and animal studies have found that intragenic pathogenic variant or haploinsufficiency in the SOX11 gene could cause inner ear malformation, but no studies to date have documented the external ear malformation caused by SOX11 deficiency. Here, we reported a Chinese male with unilateral microtia and bilateral sensorineural deafness who showed CSS-like manifestations, including dysmorphic facial features, impaired neurodevelopment, and fingers/toes malformations. Using trio-based whole-exome sequencing, a de novo missense variant in SOX11 (NM_003108.4: c.347A>G, p.Y116C) was identified and classified as pathogenic variant as per American College of Medical Genetics guidelines. Moreover, a systematic search of the literature yielded 12 publications that provided data of 55 SOX11 intragenic variants affecting various protein-coding regions of SOX11 protein. By quantitatively analyzing phenotypic spectrum information related to these 56 SOX11 variants (including our case), we found variants affecting different regions of SOX11 protein (high-mobility group [HMG] domain and non-HMG regions) appear to influence the phenotypic spectrum of organ malformations in CSS-9; variants altering the HMG domain were more likely to cause the widest range of organ anomalies. In summary, this is the first report of CSS with external ear malformation caused by pathogenic variant in SOX11, indicating that the SOX11 gene may be not only essential for the development of the inner ear but also critical for the morphogenesis of the external ear. In addition, thorough clinical examination is recommended for patients who carry pathogenic SOX11 variants that affect the HMG domain, as these variants may cause the widest range of organ anomalies underlying this condition.

Prenatal Coffin-Siris Syndrome: Expanding the Phenotypic and Genotypic Spectrum of the Disease.

Coffin-Siris syndrome is an autosomal dominant disorder with neurological, cardiovascular, and gastrointestinal symptoms. Patients with Coffin-Siris syndrome typically have variable degree of developmental delay or intellectual disability, muscular hypotonia, dysmorphic facial features, sparse scalp hair, but otherwise hirsutism and fifth digit nail or distal phalanx hypoplasia or aplasia. Coffin-Siris syndrome is caused by pathogenic variants in 12 different genes including SMARCB1 and ARID1A. Pathogenic SMARCB1 gene variants cause Coffin-Siris syndrome 3 whereas pathogenic ARID1A gene variants cause Coffin-Siris syndrome 2. Here, we present two prenatal Coffin-Siris syndrome cases with autosomal dominant pathogenic variants: SMARCB1 gene c.1066_1067del, p.(Leu356AspfsTer4) variant, and a novel ARID1A gene c.1920+3_1920+6del variant. The prenatal phenotype in Coffin-Siris syndrome has been rarely described. This article widens the phenotypic spectrum of prenatal Coffin-Siris syndrome with severely hypoplastic right ventricle with VSD and truncus arteriosus type III, persisting left superior and inferior caval vein, bilateral olfactory nerve aplasia, and hypoplastic thymus. A detailed clinical description of the patients with ultrasound, MRI, and post mortem pictures of the affected fetuses showing the wide phenotypic spectrum of the disease is presented.

Chromatin remodeler Arid1a regulates subplate neuron identity and wiring of cortical connectivity.

Loss-of-function mutations in chromatin remodeler gene ARID1A are a cause of Coffin-Siris syndrome, a developmental disorder characterized by dysgenesis of corpus callosum. Here, we characterize Arid1a function during cortical development and find unexpectedly selective roles for Arid1a in subplate neurons (SPNs). SPNs, strategically positioned at the interface of cortical gray and white matter, orchestrate multiple developmental processes indispensable for neural circuit wiring. We find that pancortical deletion of Arid1a leads to extensive mistargeting of intracortical axons and agenesis of corpus callosum. Sparse Arid1a deletion, however, does not autonomously misroute callosal axons, implicating noncell-autonomous Arid1a functions in axon guidance. Supporting this possibility, the ascending axons of thalamocortical neurons, which are not autonomously affected by cortical Arid1a deletion, are also disrupted in their pathfinding into cortex and innervation of whisker barrels. Coincident with these miswiring phenotypes, which are reminiscent of subplate ablation, we unbiasedly find a selective loss of SPN gene expression following Arid1a deletion. In addition, multiple characteristics of SPNs crucial to their wiring functions, including subplate organization, subplate axon-thalamocortical axon cofasciculation ("handshake"), and extracellular matrix, are severely disrupted. To empirically test Arid1a sufficiency in subplate, we generate a cortical plate deletion of Arid1a that spares SPNs. In this model, subplate Arid1a expression is sufficient for subplate organization, subplate axon-thalamocortical axon cofasciculation, and subplate extracellular matrix. Consistent with these wiring functions, subplate Arid1a sufficiently enables normal callosum formation, thalamocortical axon targeting, and whisker barrel development. Thus, Arid1a is a multifunctional regulator of subplate-dependent guidance mechanisms essential to cortical circuit wiring.

Identification of a novel de novo mutation in SOX4 for syndromic tooth agenesis.

OBJECTIVES: Coffin-Siris Syndrome (CSS) is a congenital disorder characterized by delayed growth, dysmorphic facial features, hypoplastic nails and phalanges of the fifth digit, and dental abnormalities. Tooth agenesis has been reported in CSS patients, but the mechanisms regulating this syndromic tooth agenesis remain largely unknown. This study aims to identify the pathogenic mutation of CSS presenting tooth genesis and explore potential regulatory mechanisms. MATERIALS AND METHODS: We utilized whole-exome sequencing to identify variants in a CSS patient, followed by Sanger validation. In silico analysis including conservation analysis, pathogenicity predictions, and 3D structural assessments were carried out. Additionally, single-cell RNA sequencing and fluorescence in situ hybridization (FISH) were applied to explore the spatio-temporal expression of Sox4 expression during murine tooth development. Weighted Gene Co-expression Network Analysis (WGCNA) was employed to examine the functional role of SOX4. RESULTS: A novel de novo SOX4 missense mutation (c.1255C > G, p.Leu419Val) was identified in a Chinese CSS patient exhibiting tooth agenesis. Single-cell RNA sequencing and FISH further verified high expression of Sox4 during murine tooth development, and WGCNA confirmed its central role in tooth development pathways. Enriched functions included cell-substrate junctions, focal adhesion, and RNA splicing. CONCLUSIONS: Our findings link a novel SOX4 mutation to syndromic tooth agenesis in CSS. This is the first report of SOX4 missense mutation causing syndromic tooth agenesis. CLINICAL RELEVANCE: This study not only enhances our understanding of the pathogenic mutation for syndromic tooth agenesis but also provides genetic diagnosis and potential therapeutic insights for syndromic tooth agenesis.

[Genetic analysis of a fetus with Coffin-Siris syndrome 2 due to a novel variant of ARID1A gene].

OBJECTIVE: To explore the genetic etiology of a fetus with Coffin-Siris syndrome (CSS). METHODS: A fetus with abnormal ultrasound findings detected at Luoyang Maternal and Child Health Care Hospital in July 2023 was selected as the study subject. Clinical data were analyzed retrospectively. Whole exome sequencing was carried out on fetal tissue and parental peripheral blood samples, and candidate variant was verified by Sanger sequencing and pathogenicity analysis. This study was approved by the Luoyang Maternal and Child Health Care Hospital (Ethics No. LYFY-YCCZ-2023011). RESULTS: Color Doppler ultrasound at 16+ gestational weeks revealed bilateral ventriculomegaly and cerebellar hypoplasia in the fetus. Trio-WES found that the fetus has harbored a heterozygous c.553C>T (p.Gln185Ter) variant of the ARID1A gene, which was verified by Sanger sequencing to have a de novo origin. Based on the guidelines from the American College of Medical Genetics and Genomics (ACMG), the c.553C>T (p.Gln185Ter) variant of the ARID1A gene was classified as pathogenic (PVS1+PS2_Supporting+PM2_Supporting). CONCLUSION: The fetus was diagnosed with CSS type 2, and the heterozygous c.553C>T (p.Gln185Ter) variant of the ARID1A gene probably underlay its brain malformations.

[The Duplicity of Incidents: Cervical Lymphatic Malformation in two Newborns]. / Die Duplizität der Ereignisse: Zervikale lymphatische Malformation bei zwei Neugeborenen.

We report on two neonates born the same day, both with an isolated cervical lymphatic malformation. Cervical masses were detected by ultrasound late in the third trimester. Following interdisciplinary case conferences, a caesarean section in the presence of a neonatal team was the chosen delivery mode in both cases. Delivery and transition of the newborns were uneventful. The suspected diagnosis was confirmed by postnatal MRIs, which demonstrated neither associated malformations nor compression of vital structures. Therefore, an expectant approach was chosen for the newborn with the smaller lesion. The other newborn featured a sizeable lymphatic malformation, and due to consecutive head tilt, sclerotherapy was initiated in its second week of life. Our case report outlines the challenges of a rare connatal malformation. Guidelines are often missing. Individual decisions regarding delivery mode, diagnostics and therapy have to be made on an interdisciplinary basis and patients as well as parents need counseling and support over a long period. All the more significant is good, interdisciplinary collaboration between the involved disciplines.

Two SOX11 variants cause Coffin-Siris syndrome with a new feature of sensorineural hearing loss.

Coffin-Siris syndrome (CSS, OMIM#135900) is a rare congenital disorder associated with neurodevelopmental and dysmorphic features. The primary cause of CSS is pathogenic variants in any of 9 BAF chromatin-remodeling complex encoding genes or the genes SOX11 and PHF6. Herein, we performed whole-exome sequencing (WES) and a series of analyses of growth-related, auditory, and radiological findings in two probands with syndromic sensorineural hearing loss and inner ear malformations who exhibited distinctive facial features, intellectual disability, growth retardation, and fifth finger malformation. Two de novo variants in the SOX11 gene (c.148A>C:p.Lys50Asn; c.811_814del:p.Asn271Serfs*10) were detected in these probands and were identified as pathogenic variants as per ACMG guidelines. These probands were diagnosed as having CSS based upon clinical and genetic findings. This is the first report of CSS caused by variants in SOX11 gene in Chinese individuals. Deleterious SOX11 variants can result in sensorineural hearing loss with inner ear malformation, potentially extending the array of phenotypes associated with these pathogenic variants. We suggest that both genetic and clinical findings be considered when diagnosing syndromic hearing loss.

Congenital diaphragmatic hernia in Coffin Siris syndrome: Further evidence from two cases.

Coffin-Siris Syndrome (CSS) is a rare multi-system dominant condition with a variable clinical presentation mainly characterized by hypoplasia/aplasia of the nail and/or distal phalanx of the fifth digit, coarse facies, hirsutism/hypertrichosis, developmental delay and intellectual disability of variable degree and growth impairment. Congenital anomalies may include cardiac, genitourinary and central nervous system malformations whereas congenital diaphragmatic hernia (CDH) is rarely reported. The genes usually involved in CSS pathogenesis are ARID1B (most frequently), SMARCA4, SMARCB1, ARID1A, SMARCE1, DPF2, and PHF6. Here, we present two cases of CSS presenting with CDH, for whom Whole Exome Sequencing (WES) identified two distinct de novo heterozygous causative variants, one in ARID1B (case 1) and one in SMARCA4 (case 2). Due to the rarity of CDH in CSS, in both cases the occurrence of CDH did not represent a predictive sign of CSS but, on the other hand, prompted genetic testing before (case 1) or independently (case 2) from the clinical hypothesis of CSS. We provide further evidence of the association between CSS and CDH, reviewed previous cases from literature and discuss possible functional links to related conditions.

Epilepsy in Coffin-Siris syndrome: A report from the international CSS registry and review of the literature.

Coffin-Siris syndrome (CSS, MIM135900) is a rare multiple congenital anomaly syndrome caused by pathogenic variants in the BAF complex; up to 28% of patients have previously been reported to have seizures, however, a comprehensive review of epilepsy has not been undertaken in this population. The International CSS Patient Report Database was queried for patients with self-reported seizures, epilepsy, and EEG results. Data gathered included demographic data, pathogenic gene variants, seizure characteristics and treatments, and EEG findings. In addition, a PubMed search was performed using keywords "Coffin-Siris syndrome" and "epilepsy," "seizures," or "EEG." Results from relevant papers are reported. Twenty-four (7.2%) of 334 patients in the database reported having seizures, EEG abnormalities, and/or epilepsy. Median age of seizure onset was 2. 7 years. Fifteen of the 23 patients with seizures or epilepsy had an ARID1B causative variant. Seventeen patients (5.1%) reported EEG abnormalities, the majority of which were described as focal or multifocal (87.5%). In all but one patient, seizures were controlled on antiseizure medications (ASMs). The literature review yielded 311 unique CSS patients, 82 of which (26.4%) carried diagnoses of seizures or epilepsy. Details on seizure type(s), EEG findings, and response to treatment were limited.

Congenital Midline Cervical Cleft (CMCC): Z-Plasty Versus Linear Cutaneous Repair.

Congenital midline cervical cleft (CMCC) is a rare congenital difference. Accurate diagnosis is important to ensure appropriate treatment. CMCC results in both functional and esthetic concerns addressed by surgical management. While the majority of reported CMCC cases have been treated with a z-plasty, the best method of repair has been debated in the literature. The authors present a case of CMCC and review of the literature.

Expanding the Spectrum of BAF-Related Disorders: De Novo Variants in SMARCC2 Cause a Syndrome with Intellectual Disability and Developmental Delay.

SMARCC2 (BAF170) is one of the invariable core subunits of the ATP-dependent chromatin remodeling BAF (BRG1-associated factor) complex and plays a crucial role in embryogenesis and corticogenesis. Pathogenic variants in genes encoding other components of the BAF complex have been associated with intellectual disability syndromes. Despite its significant biological role, variants in SMARCC2 have not been directly associated with human disease previously. Using whole-exome sequencing and a web-based gene-matching program, we identified 15 individuals with variable degrees of neurodevelopmental delay and growth retardation harboring one of 13 heterozygous variants in SMARCC2, most of them novel and proven de novo. The clinical presentation overlaps with intellectual disability syndromes associated with other BAF subunits, such as Coffin-Siris and Nicolaides-Baraitser syndromes and includes prominent speech impairment, hypotonia, feeding difficulties, behavioral abnormalities, and dysmorphic features such as hypertrichosis, thick eyebrows, thin upper lip vermilion, and upturned nose. Nine out of the fifteen individuals harbor variants in the highly conserved SMARCC2 DNA-interacting domains (SANT and SWIRM) and present with a more severe phenotype. Two of these individuals present cardiac abnormalities. Transcriptomic analysis of fibroblasts from affected individuals highlights a group of differentially expressed genes with possible roles in regulation of neuronal development and function, namely H19, SCRG1, RELN, and CACNB4. Our findings suggest a novel SMARCC2-related syndrome that overlaps with neurodevelopmental disorders associated with variants in BAF-complex subunits.

Discovering a new part of the phenotypic spectrum of Coffin-Siris syndrome in a fetal cohort.

PURPOSE: Genome-wide sequencing is increasingly being performed during pregnancy to identify the genetic cause of congenital anomalies. The interpretation of prenatally identified variants can be challenging and is hampered by our often limited knowledge of prenatal phenotypes. To better delineate the prenatal phenotype of Coffin-Siris syndrome (CSS), we collected clinical data from patients with a prenatal phenotype and a pathogenic variant in one of the CSS-associated genes. METHODS: Clinical data was collected through an extensive web-based survey. RESULTS: We included 44 patients with a variant in a CSS-associated gene and a prenatal phenotype; 9 of these patients have been reported before. Prenatal anomalies that were frequently observed in our cohort include hydrocephalus, agenesis of the corpus callosum, hypoplastic left heart syndrome, persistent left vena cava, diaphragmatic hernia, renal agenesis, and intrauterine growth restriction. Anal anomalies were frequently identified after birth in patients with ARID1A variants (6/14, 43%). Interestingly, pathogenic ARID1A variants were much more frequently identified in the current prenatal cohort (16/44, 36%) than in postnatal CSS cohorts (5%-9%). CONCLUSION: Our data shed new light on the prenatal phenotype of patients with pathogenic variants in CSS genes.

Cochlear nerve deficiency in SOX11-related Coffin-Siris syndrome.

The phenotypic spectrum of SOX11-related Coffin-Siris syndrome (CSS) is expanding with reports of new associations. SOX11 is implicated in neurogenesis and inner ear development. Cochlear nerve deficiency, absence or hypoplasia, is commonly associated with cochlear canal stenosis or with CHARGE syndrome, a monogenic condition that affects inner ear development. SOX11 is a transcription factor essential for neuronal identity, highly correlated with the expression of CHD7, which regulates SOX11. We present two unrelated probands, each with novel de novo SOX11 likely pathogenic variants and phenotypic manifestations of CSS including global developmental delay, growth deficiency, and hypoplastic nails. They have unilateral sensorineural hearing loss due to cochlear nerve deficiency confirmed on MRI. SOX11 is implicated in sensory neuron survival and maturation. It is highly expressed in the developing inner ear. Homozygous ablation of SOX11 in a mouse model resulted in a reduction in sensory neuron survival and decreased axonal growth. A heterozygous knockout mice model had hearing impairment with grossly normal inner ear structures like the two probands reported. We propose cochlear nerve deficiency as a new phenotypic feature of SOX11-related CSS. Magnetic resonance imaging is useful in delineating the cochlear nerve deficiency and other CSS-related brain malformations.

Evidence for an association between Coffin-Siris syndrome and congenital diaphragmatic hernia.

Coffin-Siris syndrome (CSS) is an autosomal dominant neurodevelopmental syndrome that can present with a variety of structural birth defects. Pathogenic variants in 12 genes have been shown to cause CSS. Most of these genes encode proteins that are a part of the mammalian switch/sucrose non-fermentable (mSWI/SNF; BAF) complex. An association between genes that cause CSS and congenital diaphragmatic hernia (CDH) has been suggested based on case reports and the analysis of CSS and CDH cohorts. Here, we describe an unpublished individual with CSS and CDH, and we report additional clinical information on four published cases. Data from these individuals, and a review of the literature, provide evidence that deleterious variants in ARID1B, ARID1A, SMARCB1, SMARCA4, SMARCE1, ARID2, DPF2, and SMARCC2, which are associated with CSS types 1-8, respectively, are associated with the development of CDH. This suggests that additional genetic testing to identify a separate cause of CDH in an individual with CSS may be unwarranted, and that comprehensive genetic testing for individuals with non-isolated CDH should include an evaluation of CSS-related genes. These data also suggest that the mSWI/SNF (BAF) complex may play an important role in diaphragm development.

Association between ARID2 and RAS-MAPK pathway in intellectual disability and short stature.

BACKGROUND: ARID2 belongs to the Switch/sucrose non-fermenting complex, in which the genetic defects have been found in patients with dysmorphism, short stature and intellectual disability (ID). As the phenotypes of patients with ARID2 mutations partially overlap with those of RASopathy, this study evaluated the biochemical association between ARID2 and RAS-MAPK pathway. METHODS: The phenotypes of 22 patients with either an ARID2 heterozygous mutation or haploinsufficiency were reviewed. Comprehensive molecular analyses were performed using somatic and induced pluripotent stem cells (iPSCs) of a patient with ARID2 haploinsufficiency as well as using the mouse model of Arid2 haploinsufficiency by CRISPR/Cas9 gene editing. RESULTS: The phenotypic characteristics of ARID2 deficiency include RASopathy, Coffin-Lowy syndrome or Coffin-Siris syndrome or undefined syndromic ID. Transient ARID2 knockout HeLa cells using an shRNA increased ERK1 and ERK2 phosphorylation. Impaired neuronal differentiation with enhanced RAS-MAPK activity was observed in patient-iPSCs. In addition, Arid2 haploinsufficient mice exhibited reduced body size and learning/memory deficit. ARID2 haploinsufficiency was associated with reduced IFITM1 expression, which interacts with caveolin-1 (CAV-1) and inhibits ERK activation. DISCUSSION: ARID2 haploinsufficiency is associated with enhanced RAS-MAPK activity, leading to reduced IFITM1 and CAV-1 expression, thereby increasing ERK activity. This altered interaction might lead to abnormal neuronal development and a short stature.