Project description:Some genetic disorders caused by mutations in genes encoding components of the transcriptional machinery as well as proteins involved in epigenetic modification of the genome share many overlapping features, such as facial dysmorphisms, growth problems and developmental delay/intellectual disability. As a basis for some shared phenotypic characteristics in these syndromes, a similar transcriptome disturbance, characterized by global transcriptional dysregulation, is believed to play a major role. In this review article, a general overview of gene transcription is provided, and the current knowledge of the mechanisms underlying some disorders of transcriptional regulation, such as Rubinstein- Taybi, Coffin-Siris, Cornelia de Lange, and CHOPS syndromes, are discussed.
Project description:The cohesin protein complex is essential for the formation of topologically associating domains (TADs) and chromatin loops on interphase chromosomes. For the loading onto chromosomes, cohesin requires the cohesin loader complex formed by NIPBL and MAU2. Cohesin localizes at enhancers and gene promoters with NIPBL in mammalian cells and forms enhancer-promoter loops. Cornelia de Lange syndrome (CdLS) is a rare, genetically heterogeneous disorder affecting multiple organs and systems during development, caused by mutations in the cohesin loader NIPBL gene (> 60% of patients), as well as in genes encoding cohesin, a chromatin regulator, BRD4, and cohesin-related factors. We also reported CHOPS syndrome that phenotypically overlaps with CdLS and is caused by gene mutations of a super elongation complex (SEC) core component, AFF4. Although these syndromes are associated with transcriptional dysregulation, the underlying mechanism remains unclear. In this study, we provide the first comprehensive analysis of chromosome architectural changes caused by these mutations using cell lines derived from CdLS and CHOPS syndrome patients. In both patient cells, we found a decrease in cohesin, NIPBL, BRD4, and acetylation of lysine 27 on histone H3 (H3K27ac) in most enhancers with enhancer-promoter loop attenuation. In contrast, TADs were maintained in both patient cells. These findings reveal a shared molecular mechanism in these syndromes and highlight unexpected roles for cohesin, cohesin loaders, and the SEC in maintaining the enhancer complexes. These complexes are crucial for recruiting transcriptional regulators, sustaining active histone modifications, and facilitating enhancer-promoter looping.
Project description:The cohesin protein complex is essential for the formation of topologically associating domains (TADs) and chromatin loops on interphase chromosomes. For the loading onto chromosomes, cohesin requires the cohesin loader complex formed by NIPBL and MAU2. Cohesin localizes at enhancers and gene promoters with NIPBL in mammalian cells and forms enhancer-promoter loops. Cornelia de Lange syndrome (CdLS) is a rare, genetically heterogeneous disorder affecting multiple organs and systems during development, caused by mutations in the cohesin loader NIPBL gene (> 60% of patients), as well as in genes encoding cohesin, a chromatin regulator, BRD4, and cohesin-related factors. We also reported CHOPS syndrome that phenotypically overlaps with CdLS and is caused by gene mutations of a super elongation complex (SEC) core component, AFF4. Although these syndromes are associated with transcriptional dysregulation, the underlying mechanism remains unclear. In this study, we provide the first comprehensive analysis of chromosome architectural changes caused by these mutations using cell lines derived from CdLS and CHOPS syndrome patients. In both patient cells, we found a decrease in cohesin, NIPBL, BRD4, and acetylation of lysine 27 on histone H3 (H3K27ac) in most enhancers with enhancer-promoter loop attenuation. In contrast, TADs were maintained in both patient cells. These findings reveal a shared molecular mechanism in these syndromes and highlight unexpected roles for cohesin, cohesin loaders, and the SEC in maintaining the enhancer complexes. These complexes are crucial for recruiting transcriptional regulators, sustaining active histone modifications, and facilitating enhancer-promoter looping.
Project description:During recent decades, the autoimmune disease neuromyelitis optica spectrum disorder (NMOSD), once broadly classified under the umbrella of multiple sclerosis (MS), has been extended to include autoimmune inflammatory conditions of the central nervous system (CNS), which are now diagnosable with serum serological tests. These antibody-mediated inflammatory diseases of the CNS share a clinical presentation to MS. A number of practical learning points emerge in this review, which is geared toward the pattern recognition of optic neuritis, transverse myelitis, brainstem/cerebellar and hemispheric tumefactive demyelinating lesion (TDL)-associated MS, aquaporin-4-antibody and myelin oligodendrocyte glycoprotein (MOG)-antibody NMOSD, overlap syndrome, and some yet-to-be-defined/classified demyelinating disease, all unspecifically labeled under MSsyndrome. The goal of this review is to increase clinicians' awareness of the clinical nuances of the autoimmune conditions for MS and NMSOD, and to highlight highly suggestive patterns of clinical, paraclinical or imaging presentations in order to improve differentiation. With overlay in clinical manifestations between MS and NMOSD, magnetic resonance imaging (MRI) of the brain, orbits and spinal cord, serology, and most importantly, high index of suspicion based on pattern recognition, will help lead to the final diagnosis.
Project description:PRKACA and PRKACB code for two catalytic subunits (Cα and Cβ) of cAMP-dependent protein kinase (PKA), a pleiotropic holoenzyme that regulates numerous fundamental biological processes such as metabolism, development, memory, and immune response. We report seven unrelated individuals presenting with a multiple congenital malformation syndrome in whom we identified heterozygous germline or mosaic missense variants in PRKACA or PRKACB. Three affected individuals were found with the same PRKACA variant, and the other four had different PRKACB mutations. In most cases, the mutations arose de novo, and two individuals had offspring with the same condition. Nearly all affected individuals and their affected offspring shared an atrioventricular septal defect or a common atrium along with postaxial polydactyly. Additional features included skeletal abnormalities and ectodermal defects of variable severity in five individuals, cognitive deficit in two individuals, and various unusual tumors in one individual. We investigated the structural and functional consequences of the variants identified in PRKACA and PRKACB through the use of several computational and experimental approaches, and we found that they lead to PKA holoenzymes which are more sensitive to activation by cAMP than are the wild-type proteins. Furthermore, expression of PRKACA or PRKACB variants detected in the affected individuals inhibited hedgehog signaling in NIH 3T3 fibroblasts, thereby providing an underlying mechanism for the developmental defects observed in these cases. Our findings highlight the importance of both Cα and Cβ subunits of PKA during human development.
Project description:Identification of the inner ear malformation types from radiographs is a complex process. We hypothesize that each inner ear anatomical type has a uniqueness in its appearance in radiographs. The outer contour of the inner ear was captured from the mid-modiolar section, perpendicular to the oblique-coronal plane, from which the A-value was determined from CT scans with different inner ear anatomical types. The mean A-value of normal anatomy (NA) and enlarged vestibular aqueduct syndrome (EVAS) anatomical types was greater than for Incomplete Partition (IP) type I, II, III and cochlear hypoplasia. The outer contour of the cochlear portion within the mid-modiolar section of NA and EVAS resembles the side view of Aladdin's lamp; IP type I resembles the side-view of the Sphinx pyramid and type II a Pomeranian dog's face. The steep spiraling cochlear turns of IP type III resemble an Auger screw tip. Drawing a line parallel to the posterior margin of internal auditory canal (IAC) in axial-view, bisecting the cavity into cochlear and vestibular portions, identifies common-cavity; whereas a cavity that falls under the straight-line leaving no cochlear portion identifies cochlear aplasia. An atlas of the outer contour of seventy-eight inner ears was created for the identification of the inner malformation types precisely.
Project description:Cholesterol homeostasis is critical for normal growth and development. In addition to being a major membrane lipid, cholesterol has multiple biological functions. These roles include being a precursor molecule for the synthesis of steroid hormones, neuroactive steroids, oxysterols, and bile acids. Cholesterol is also essential for the proper maturation and signaling of hedgehog proteins, and thus cholesterol is critical for embryonic development. After birth, most tissues can obtain cholesterol from either endogenous synthesis or exogenous dietary sources, but prior to birth, the human fetal tissues are dependent on endogenous synthesis. Due to the blood-brain barrier, brain tissue cannot utilize dietary or peripherally produced cholesterol. Generally, inborn errors of cholesterol synthesis lead to both a deficiency of cholesterol and increased levels of potentially bioactive or toxic precursor sterols. Over the past couple of decades, a number of human malformation syndromes have been shown to be due to inborn errors of cholesterol synthesis. Herein, we will review clinical and basic science aspects of Smith-Lemli-Opitz syndrome, desmosterolosis, lathosterolosis, HEM dysplasia, X-linked dominant chondrodysplasia punctata, Congenital Hemidysplasia with Ichthyosiform erythroderma and Limb Defects Syndrome, sterol-C-4 methyloxidase-like deficiency, and Antley-Bixler syndrome.
Project description:Multiple malformation syndromes (MMS) belong to a group of genetic disorders characterised by neurodevelopmental anomalies and congenital malformations. Here we explore for the first time the genetic aetiology of MMS using whole-exome sequencing (WES) in undiagnosed patients from the Greek-Cypriot population after prior extensive diagnostics workup including karyotype and array-CGH. A total of 100 individuals (37 affected), from 32 families were recruited and family-based WES was applied to detect causative single-nucleotide variants (SNVs) and indels. A genetic diagnosis was reported for 16 MMS patients (43.2%), with 10/17 (58.8%) of the findings being novel. All autosomal dominant findings occurred de novo. Functional studies were also performed to elucidate the molecular mechanism relevant to the abnormal phenotypes, in cases where the clinical significance of the findings was unclear. The 17 variants identified in our cohort were located in 14 genes (PCNT, UBE3A, KAT6A, SPR, POMGNT1, PIEZO2, PXDN, KDM6A, PHIP, HECW2, TFAP2A, CNOT3, AGTPBP1 and GAMT). This study has highlighted the efficacy of WES through the high detection rate (43.2%) achieved for a challenging category of undiagnosed patients with MMS compared to other conventional diagnostic testing methods (10-20% for array-CGH and ~3% for G-banding karyotype analysis). As a result, family-based WES could potentially be considered as a first-tier cost effective diagnostic test for patients with MMS that facilitates better patient management, prognosis and offer accurate recurrence risks to the families.
Project description:OBJECTIVE: Here, we use pattern-classification to investigate diagnostic information for multiple sclerosis (MS; relapsing-remitting type) in lesioned areas, areas of normal-appearing grey matter (NAGM), and normal-appearing white matter (NAWM) as measured by standard MR techniques. METHODS: A lesion mapping was carried out by an experienced neurologist for Turbo Inversion Recovery Magnitude (TIRM) images of individual subjects. Combining this mapping with templates from a neuroanatomic atlas, the TIRM images were segmented into three areas of homogenous tissue types (Lesions, NAGM, and NAWM) after spatial standardization. For each area, a linear Support Vector Machine algorithm was used in multiple local classification analyses to determine the diagnostic accuracy in separating MS patients from healthy controls based on voxel tissue intensity patterns extracted from small spherical subregions of these larger areas. To control for covariates, we also excluded group-specific biases in deformation fields as a potential source of information. RESULTS: Among regions containing lesions a posterior parietal WM area was maximally informative about the clinical status (96% accuracy, p<10(-13)). Cerebellar regions were maximally informative among NAGM areas (84% accuracy, p<10(-7)). A posterior brain region was maximally informative among NAWM areas (91% accuracy, p<10(-10)). INTERPRETATION: We identified regions indicating MS in lesioned, but also NAGM, and NAWM areas. This complements the current perception that standard MR techniques mainly capture macroscopic tissue variations due to focal lesion processes. Compared to current diagnostic guidelines for MS that define areas of diagnostic information with moderate spatial specificity, we identified hotspots of MS associated tissue alterations with high specificity defined on a millimeter scale.