Search Results (32)

Chromosome 6q deletion syndrome is a rare entity that has a highly variable clinical presentation and size of deletions. The most frequent manifestations of 6q terminal deletion are intellectual disability, facial dysmorphism, brain structural anomalies, and congenital heart defects. The phenotype is not clinically recognizable, except in those who harbor a terminal 6q deletion that includes the ARID1B gene, in whom features similar to Coffin–Siris syndrome (CSS) can be observed. We report the case of a female newborn with a prenatal diagnosis of a terminal deletion on 6q25.1q27, which encompasses the ARID1B gene, and who was diagnosed with CSS during the neonatal period. From our review, we found that facial gestalt, hypertrichosis, and fifth fingernail aplasia/hypoplasia, along with other features, such as vertebral defects and cystic hygroma (or webbed neck), correlated with the presence of a CSS causally related to 6q25.3 small deletions that include the ARID1B gene. Full article

Weaver syndrome is a rare congenital overgrowth disorder caused by pathogenic EZH2 variants. This study reports a novel EZH2 variant associated with atypical manifestations, including severe bilateral camptodactyly and complex brain malformations. A 4-year-old Taiwanese female exhibited classical Weaver syndrome features including macrosomia, macrocephaly, hypertelorism, and developmental delay, plus atypical findings of severe bilateral camptodactyly and complex brain malformations. Neuroimaging revealed corpus callosum dysgenesis with rostral agenesis and genu hypoplasia, bilateral frontal lobe hypoplasia, and an arachnoid cyst. The patient demonstrated global developmental delay with marked motor impairment but less severely affected speech and cognition, consistent with mild intellectual disability. Whole-exome sequencing identified a novel de novo pathogenic variant in EZH2: c.449T>C (p.Ile150Thr), affecting a highly conserved amino acid within the SANT domain. This case broadens the clinical spectrum of Weaver syndrome by highlighting severe camptodactyly and complex brain malformations as possible EZH2-related manifestations. The corpus callosum dysgenesis suggests a wider role of EZH2 in neurodevelopment than previously recognized. The novel SANT domain variant may explain the severe phenotypic presentation. The novel EZH2 variant c.449T>C (p.Ile150Thr) expands the molecular and phenotypic spectrum of Weaver syndrome. These findings underscore the importance of comprehensive neuroimaging and molecular genetic testing in suspected cases, particularly atypical presentations. Full article

RAC3 encodes a small Rho-family GTPase essential for cytoskeletal regulation and neurodevelopment, and de novo RAC3 variants typically act as gain-of-function alleles that cause severe neurodevelopmental disorders. In this study, we analyzed a fetus with multisystem congenital anomalies and identified a de novo RAC3 p.(T17R) variant by genome sequencing. To elucidate the pathogenicity of this variant, we combined in silico variant prioritization, structural and energetic modeling, and pathogenicity prediction with in vitro biochemical assays, including GDP/GTP exchange, GTP hydrolysis, effector pull-down, and luciferase reporter analyses in COS7 cells, as well as morphological analysis of primary hippocampal neurons. Furthermore, we performed in vivo analyses using a mouse in utero electroporation to assess cortical neuron migration, axon extension, and dendritic development. Our biochemical results suggest that RAC3-T17R exhibits markedly increased GDP/GTP exchange, with a preference for GDP binding, and undetectable GTP hydrolysis. The mutant displayed minimal binding to canonical RAC effectors (PAK1, MLK2, and N-WASP) and failed to activate SRF-, NFκB-, or AP1-dependent transcription. Neuronal overexpression of RAC3-T17R impaired axon formation in vitro, while in vivo expression delayed cortical neuron migration and axon extension and reduced dendritic arborization. Clinically, the fetus exhibited corpus callosum agenesis, microcephaly, organomegaly, and limb contractures. Collectively, these findings indicate that the RAC3 p.(T17R) variant may represent a signaling-deficient allele with pleiotropic, variant-specific mechanisms that disrupt corticogenesis and broader organogenesis. Our multi-tiered in silico–in vitro–in vivo approach demonstrates that noncanonical RAC3 variants can produce complex, multisystem developmental phenotypes beyond previously recognized RAC3-related neurodevelopmental disorders. Full article

Background/Objectives: Joubert syndrome (JS, MIM 213300) is a rare genetic condition characterized by respiratory control disturbances, abnormal eye movements, ataxia, cognitive impairment, and the notable agenesis of the cerebellar vermis. The molar tooth sign visible in magnetic resonance imaging of the brain serves as a diagnostic tool for JS. Variants in the TCTN3 gene can lead to the development of several diseases, including JS type 18, Orofaciodigital syndrome IV, and Meckel–Gruber syndrome. Methods: We performed whole-exome sequencing (WES) in a 49-year-old woman with JS characterized by severe intellectual disability, ataxic gait, agenesis of the cerebellar vermis leading to the molar tooth sign, dystonic movements, strabismus, and nystagmus. Moreover, the patient also showed a thickened corpus callosum. Results: Molecular analysis through WES revealed the heterozygous variants c.182dup (p.G62Wfs*18) and c.1452+4del in the TCTN3 gene, expanding our understanding of the genetic diversity and potential phenotypic implications associated with TCTN3 variations. Conclusions: To our knowledge, this is the first patient with JS and a thickened corpus callosum. Moreover, a thickened corpus callosum has never been identified in patients with pathogenic variants of the TCTN3 gene. Full article

SCY1 Like Pseudokinase 2 (SCYL2) is a protein that regulates secretory protein trafficking and plays a pivotal role in neurodevelopment by attenuating excitotoxicity. Neurogenic arthrogryposis due to SCYL2 mutations, also known as arthrogryposis multiplex congenita 4 (AMC4), is a rare condition that presents with microcephaly, agenesis of the corpus callosum, optic atrophy, global developmental delay, and early lethality. We used whole-exome sequencing to identify pathogenic variants, DynaMut2 to determine the predicted effect on protein stability, and Western blot to investigate the effect on protein expression. We present two novel missense mutations in SCYL2 resulting in loss of function at the protein level in a pediatric case of AMC4, further highlighting the key role of SCYL2 in neuronal cell survival and healthy brain development. There is diversity in the pathological features among previously published cases of AMC4, most likely due to the nature of each mutation. This report summarizes the clinical data of all known patients with SCYL2 mutations. Full article

Oropouche virus (OROV) is an orthobunyavirus endemic in the Brazilian Amazon that has caused numerous outbreaks of febrile disease since its discovery in 1955. During 2024, Oropouche fever spread from the endemic regions of Brazil into non-endemic areas and other Latin American and Caribbean countries, resulting in 13,014 confirmed infections. Similarly to other orthobunyaviruses, OROV can undergo genetic reassortment events with itself as well as other viruses. This occurred during this current outbreak, resulting in novel strains with increased pathogenicity and levels of transmission. For the first time, pregnant women with Oropouche fever have sustained poor perinatal outcomes, including miscarriage, fetal demise, stillbirths and malformation syndromes including microcephaly. In July 2024, PAHO issued an Epidemiological Alert warning of the association of OROV with vertical transmission. OROV has now been identified in the fetal blood, cerebrospinal fluid, placenta and umbilical cords, and fetal somatic organs including the liver, kidneys, brain, spleen, heart, and lungs using nucleic acid and antigen testing. Perinatal autopsy pathology has confirmed central nervous system infection from OROV in infants with congenital infection including microcephaly, ventriculomegaly, agenesis of corpus callosum, and neuronal necrosis. The latest data from Brazil show 3 confirmed cases of OROV vertical transmission; 2 cases of fetal death; 1 case of congenital malformation; and ongoing investigations into the role of OROV in 15 cases of fetal death, 3 cases of congenital malformations and 5 spontaneous miscarriages. This Commentary discusses the mechanisms and significance of development of novel reassortant strains of OROV during the current outbreak and their recent recognition as causing vertical infection and adverse perinatal outcomes among pregnant women with Oropouche fever. Full article

RAC3 encodes a small GTPase of the Rho family that plays a critical role in actin cytoskeleton remodeling and intracellular signaling regulation. Pathogenic variants in RAC3, all of which reported thus far affect conserved residues within its functional domains, have been linked to neurodevelopmental disorders characterized by diverse phenotypic features, including structural brain anomalies and facial dysmorphism (NEDBAF). Recently, a novel de novo RAC3 variant (NM_005052.3): c.196C>T, p.R66W was identified in a prenatal case with fetal akinesia deformation sequence (a spectrum of conditions that interfere with the fetus’s ability to move), and complex brain malformations featuring corpus callosum agenesis, diencephalosynapsis, kinked brainstem, and vermian hypoplasia. To investigate the mechanisms underlying the association between RAC3 deficiency and this unique, distinct clinical phenotype, we explored the pathophysiological significance of the p.R66W variant in brain development. Biochemical assays revealed a modest enhancement in intrinsic GDP/GTP exchange activity and an inhibitory effect on GTP hydrolysis. Transient expression studies in COS7 cells demonstrated that RAC3-R66W interacts with the downstream effectors PAK1, MLK2, and N-WASP but fails to activate SRF-, AP1-, and NFkB-mediated transcription. Additionally, overexpression of RAC3-R66W significantly impaired differentiation in primary cultured hippocampal neurons. Acute expression of RAC3-R66W in vivo by in utero electroporation resulted in impairments in cortical neuron migration and axonal elongation during corticogenesis. Collectively, these findings suggest that the p.R66W variant may function as an activated version in specific signaling pathways, leading to a distinctive and severe prenatal phenotype through variant-specific mechanisms. Full article

The ARX mutations encompass a nearly continuous spectrum of neurodevelopmental disorders (NDDs), ranging from lissencephaly to Proud syndrome, as well as infantile spasms without brain malformations, and including both syndromic and non-syndromic intellectual disabilities (IDs). We describe worsening neuropsychiatric symptoms in the offspring of a Korean family with ID/developmental delay (DD) caused by a novel ARX p.Lys385Ter variant. Sequential genetic testing was performed to investigate the ID, DD, agenesis of the corpus callosum (ACC), and developmental epileptic encephalopathy (DEE) observed in the proband. A comprehensive trio clinical exome sequencing approach using a Celemics G-Mendeliome Clinical Exome Sequencing Panel was employed. Given the clinical manifestations observed in the proband, gene panel sequencing identified a heterozygous ARX variant, c.1153A>T/p.Lys385Ter (Reference transcript ID: NM_139058.3), as the most likely cause of ID, DD, ACC, and DEE in the proband. Sanger sequencing confirmed the segregation of the ARX variant, c.1153A>T/p.Lys385Ter, with the phenotype and established the maternally inherited dominant status of the heterozygous variant in the patient, as well as in her grandmother, mother, and aunt. Our case report adds to the understanding of the female phenotype in ARX-related disorders caused by loss-of-function variants in the ARX gene. Genetic counseling for ARX families should proceed with caution, as female carriers can exhibit a wide range of phenotypes, from normal cognitive development to ID/DD, ACC, and DEE. Full article

Introduction: The corpus callosum is one of the five main cerebral commissures. It is key to combining sensory and motor functions. Its structure can be pathological (dysgenesis) or completely absent (agenesis). The corpus callosum dys- or agenesis is a rare disease (1:4000 live births), but it can have serious mental effects. Methods: In our study, we processed the data of 64 pregnant women. They attended a prenatal diagnostic center and genetic counseling from 2005 to 2019 at the Department of Obstetrics and Gynecology at Semmelweis University. Results: The pregnancies had the following outcomes: 52 ended in delivery, 1 in spontaneous abortion, and 11 in termination of pregnancy (TOP) cases (n = 64). The average time of detection with imaging tests was 25.24 gestational weeks. In 16 cases, prenatal magnetic resonance imaging (MRI) was performed. If the abnormality was detected before the 20th week, a genetic test was performed on an amniotic fluid sample obtained from a genetic amniocentesis. Karyotyping and cytogenetic tests were performed in 15 of the investigated cases. Karyotyping gave normal results in three cases (46,XX or XY). In one of these cases, postnatally chromosomal microarray (CMA) was later performed, which confirmed Aicardi syndrome (3q21.3–21.1 microdeletion). In one case, postnatally, the test found Wiedemann–Rautenstrauch syndrome. In other cases, it found X ring, Di George syndrome, 46,XY,del(13q)(q13q22) and 46,XX,del(5p)(p13) (Cri-du-chat syndrome). Edwards syndrome was diagnosed in six cases, and Patau syndrome in one case. Conclusions: We found that corpus callosum abnormalities are often linked to chromosomal problems. We recommend that a cytogenetic test be performed in all cases to rule out inherited diseases. Also, the long-term outcome does not just depend on the disease’s severity and the associated other conditions, and hence proper follow-up and early development are also key. For this reason, close teamwork between neonatology, developmental neurology, and pediatric surgery is vital. Full article

Fryns syndrome (FS) is a multiple congenital anomaly syndrome with different multisystemic malformations. These include congenital diaphragmatic hernia, pulmonary hypoplasia, and craniofacial dysmorphic features in combination with malformations of the central nervous system such as agenesis of the corpus callosum, cerebellar hypoplasia, and enlarged ventricles. We present a non-consanguineous northern European family with two recurrent cases of FS: a boy with multiple congenital malformations who died at the age of 2.5 months and a female fetus with a complex developmental disorder with similar features in a following pregnancy. Quad whole exome analysis revealed two likely splicing-affecting disease-causing mutations in the PIGN gene: a synonymous mutation c.2619G>A, p.(Leu873=) in the last nucleotide of exon 29 and a 30 bp-deletion c.996_1023+2del (NM_176787.5) protruding into intron 12, with both mutations in trans configuration in the affected patients. Exon skipping resulting from these two variants was confirmed via RNA sequencing. Our molecular and clinical findings identified compound heterozygosity for two novel splice-affecting variants as the underlying pathomechanism for the development of FS in two patients. Full article

The L1 cell adhesion molecule (L1) has demonstrated a range of beneficial effects in animal models of spinal cord injury, neurodegenerative disease, and ischemia; however, the role of L1 in TBI has not been fully examined. Mutations in the L1 gene affecting the extracellular domain of this type 1 transmembrane glycoprotein have been identified in patients with L1 syndrome. These patients suffer from hydrocephalus, MASA (mental retardation, adducted thumbs, shuffling gait, aphasia) symptoms, and corpus callosum agenesis. Clinicians have observed that recovery post-traumatic brain injury (TBI) varies among the population. This variability may be explained by the genetic differences present in the general population. In this study, we utilized a novel mouse model of L1 syndrome with a mutation at aspartic acid position 201 in the extracellular domain of L1 (L1-201). We assessed the impact of this specific single nucleotide polymorphism (SNP) localized to the X-chromosome L1 gene on recovery outcomes following TBI by comparing the L1-201 mouse mutants with their wild-type littermates. We demonstrate that male L1-201 mice exhibit significantly worse learning and memory outcomes in the Morris water maze after lateral fluid percussion (LFP) injury compared to male wild-type mice and a trend to worse motor function on the rotarod. However, no significant changes were observed in markers for inflammatory responses or apoptosis after TBI. Full article

Background/Objectives: Pathogenic variants in the deleted in colorectal cancer gene (DCC), encoding the Netrin-1 receptor, may lead to mirror movements (MMs) associated with agenesis/dysgenesis of the corpus callosum (ACC) and cognitive and/or neuropsychiatric issues. The clinical phenotype is related to the biological function of DCC in the corpus callosum and corticospinal tract development as Netrin-1 is implicated in the guidance of developing axons toward the midline. We report on a child with a novel inherited, monoallelic, pathogenic variant in the DCC gene. Methods: Standardized measures and clinical scales were used to assess psychomotor development, communication and social skills, emotional and behavioural difficulties. MMs were measured via the Woods and Teuber classification. Exome sequencing was performed on affected and healthy family members. Results: The patient’s clinical presentation during infancy consisted of paroxysmal dystonic posturing when asleep, mimicking nocturnal leg cramps. A brain magnetic resonance imaging (MRI) showed complete ACC. He developed typical upper limb MMs during childhood and a progressively evolving neuro-phenotype with global development delay and behavioural problems. We found an intrafamilial clinical variability associated with DCC mutations: the proband’s father and uncle shared the same DCC variant, with a milder clinical phenotype. The atypical early clinical presentation of the present patient expands the clinical spectrum associated with DCC variants, especially those in the paediatric age. Conclusions: This study underlines the importance of in-depth genetic investigations in young children with ACC and highlights the need for further detailed analyses of early motor symptoms in infants with DCC mutations. Full article

Background. Corpus callosal abnormalities (CCA) are midline developmental brain malformations and are usually associated with a wide spectrum of other neurological and non-neurological abnormalities. The study aims to highlight the diagnostic role of fetal MRI to characterize heterogeneous corpus callosal abnormalities using the latest classification system. It also helps to identify associated anomalies, which have prognostic implications for the postnatal outcome. Methods. In this study, retrospective data from antenatal women who underwent fetal MRI between January 2014 and July 2023 at Rush University Medical Center were evaluated for CCA and classified based on structural morphology. Patients were further assessed for associated neurological and non-neurological anomalies. Results. The most frequent class of CCA was complete agenesis (79.1%), followed by hypoplasia (12.5%), dysplasia (4.2%), and hypoplasia with dysplasia (4.2%). Among them, 17% had isolated CCA, while the majority (83%) had complex forms of CCA associated with other CNS and non-CNS anomalies. Out of the complex CCA cases, 58% were associated with other CNS anomalies, while 8% were associated with non-CNS anomalies. 17% of cases had both. Conclusion. The use of fetal MRI is valuable in the classification of abnormalities of the corpus callosum after the confirmation of a suspected diagnosis on prenatal ultrasound. This technique is an invaluable method for distinguishing between isolated and complex forms of CCA, especially in cases of apparent isolated CCA. The use of diffusion-weighted imaging or diffusion tensor imaging in fetal neuroimaging is expected to provide further insights into white matter abnormalities in fetuses diagnosed with CCA in the future. Full article

Aicardi Syndrome (AIC) is a rare neurodevelopmental disorder recognized by the classical triad of agenesis of the corpus callosum, chorioretinal lacunae and infantile epileptic spasms syndrome. The diagnostic criteria of AIC were revised in 2005 to include additional phenotypes that are frequently observed in this patient group. AIC has been traditionally considered as X-linked and male lethal because it almost exclusively affects females. Despite numerous genetic and genomic investigations on AIC, a unifying X-linked cause has not been identified. Here, we performed exome and genome sequencing of 10 females with AIC or suspected AIC based on current criteria. We identified a unique de novo variant, each in different genes: KMT2B, SLF1, SMARCB1, SZT2 and WNT8B, in five of these females. Notably, genomic analyses of coding and non-coding single nucleotide variants, short tandem repeats and structural variation highlighted a distinct lack of X-linked candidate genes. We assessed the likely pathogenicity of our candidate autosomal variants using the TOPflash assay for WNT8B and morpholino knockdown in zebrafish (Danio rerio) embryos for other candidates. We show expression of Wnt8b and Slf1 are restricted to clinically relevant cortical tissues during mouse development. Our findings suggest that AIC is genetically heterogeneous with implicated genes converging on molecular pathways central to cortical development. Full article

Interstitial deletions in the long arm of chromosome 3, although relatively rare, have previously been reported to be associated with several congenital anomalies and developmental delays. Around 11 individuals with interstitial deletion spanning the region 3q21 were reported to have overlapping phenotypes, including craniofacial dysmorphism, global developmental delay, skeletal manifestations, hypotonia, ophthalmological abnormalities, brain anomalies (mainly agenesis of corpus callosum), genitourinary tract anomalies, failure to thrive and microcephaly. We present a male individual from Kuwait with a 5.438 Mb interstitial deletion of the long arm of chromosome 3 (3q21.1q21.3) detected on the chromosomal microarray with previously unreported features, including feeding difficulties, gastroesophageal reflux, hypospadias, abdomino-scrotal hydrocele, chronic kidney disease, transaminitis, hypercalcemia, hypoglycemia, recurrent infections, inguinal hernia and cutis marmorata. Our report expands the phenotype associated with 3q21.1q21.3 while summarizing the cytogenetics and clinical data of the previously reported individuals with interstitial deletions involving 3q21, thus providing a comprehensive phenotypic summary. Full article