First Case Report of Developmental Bilateral Cataract with a Novel Mutation in the ZEB2 Gene Observed in Mowat-Wilson Syndrome

Peter C, Lovell S, Rafi SK, Butler MG. ZEB2 Gene Pathogenic Variants Across Protein-Coding Regions and Impact on Clinical Manifestations: A Review

Mowat-Wilson syndrome (MWS) is a rare multi-system genetic disorder caused by variants in the Zinc Finger E-Box-Binding Homeobox 2 (ZEB2) gene. ZEB2 is an autosomal dominant gene containing ten exons within the canonical version transcript (Isoform: O60315-1). The ZEB2 gene encodes six functional domains and seven non-domain regions. This review provides a comprehensive summary of pathogenic variants and their associated MWS clinical characteristics, focusing on ZEB2 pathogenic variants, functional protein domains and non-domain regions with clinical features. A systematic literature search from 2001 to 2023 and of unpublished datasets found 191 individuals with reported clinical features and genotypic data. Genetic defects and clinical manifestations were examined that presumably impact on the structure and function of the ZEB2 gene, thereby causing multiple developmental defects with corresponding clinical presentation. This study found more nonsense ZEB2 variants observed within exon 8, which encodes four of the six protein domains: the CtBP-interacting domain (CID), homeodomain (HD), SMAD-binding domain (SMD or SBD) and part of the N-terminal zinc finger cluster (N-ZF), suggesting exon 8 plays a crucial role in this protein structure and function with multi-organ involvement. Exon 8 defects were found to be statistically more represented for gastrointestinal findings when compared to other exons, while frameshift defects were more often seen for the typical MWS face in non-domain protein regions. In contrast, nonsense or other types of variants in exons 3, 4 and 5 which encode only flanking non-domain regions were observed more often, compared with other exons excluding exon 8, to be specifically involved in the MWS facial gestalt, brain malformations, developmental delay and intellectual disability. Deleterious ZEB2 frameshift (45%) and nonsense (38%) gene variants were most often observed with deletions at 6% and missense at 5%. The genotype and clinical relationships in MWS can provide insights into prognosis, morbidity, clinical surveillance strategies and counseling of family members.

Clinical and Genetic Correlation in Neurocristopathies: Bridging a Precision Medicine Gap

Neurocristopathies (NCPs) encompass a spectrum of disorders arising from issues during the formation and migration of neural crest cells (NCCs). NCCs undergo epithelial-mesenchymal transition (EMT) and upon key developmental gene deregulation, fetuses and neonates are prone to exhibit diverse manifestations depending on the affected area. These conditions are generally rare and often have a genetic basis, with many following Mendelian inheritance patterns, thus making them perfect candidates for precision medicine. Examples include cranial NCPs, like Goldenhar syndrome and Axenfeld-Rieger syndrome; cardiac-vagal NCPs, such as DiGeorge syndrome; truncal NCPs, like congenital central hypoventilation syndrome and Waardenburg syndrome; and enteric NCPs, such as Hirschsprung disease. Additionally, NCCs' migratory and differentiating nature makes their derivatives prone to tumors, with various cancer types categorized based on their NCC origin. Representative examples include schwannomas and pheochromocytomas. This review summarizes current knowledge of diseases arising from defects in NCCs' specification and highlights the potential of precision medicine to remedy a clinical phenotype by targeting the genotype, particularly important given that those affected are primarily infants and young children.

Mowat-Wilson syndrome: unraveling the complexities of diagnosis, treatment, and symptom management

Mowat-Wilson syndrome can be mentioned as one of the most severe and, at the same time, rare genetic abnormalities. The inheritance pattern of this disorder is an autosomal dominant pattern. In this disease, the ZEB2 gene becomes abnormal. The severity of the disease and associated signs and symptoms can vary widely but may include distinct facial features, developmental delay, intellectual disability, and Hirschsprung. MWS treatment may vary based on the specific symptoms that appear in each individual. This review will examine the gene involved in this disease, phenotype, clinical manifestations, ways of diagnosis, and treatment of this disease.

Mowat-Wilson Syndrome: Case Report and Review of ZEB2 Gene Variant Types, Protein Defects and Molecular Interactions

Mowat-Wilson syndrome (MWS) is a rare genetic neurodevelopmental congenital disorder associated with various defects of the zinc finger E-box binding homeobox 2 (ZEB2) gene. The ZEB2 gene is autosomal dominant and encodes six protein domains including the SMAD-binding protein, which functions as a transcriptional corepressor involved in the conversion of neuroepithelial cells in early brain development and as a mediator of trophoblast differentiation. This review summarizes reported ZEB2 gene variants, their types, and frequencies among the 10 exons of ZEB2. Additionally, we summarized their corresponding encoded protein defects including the most common variant, c.2083 C>T in exon 8, which directly impacts the homeodomain (HD) protein domain. This single defect was found in 11% of the 298 reported patients with MWS. This review demonstrates that exon 8 encodes at least three of the six protein domains and accounts for 66% (198/298) of the variants identified. More than 90% of the defects were due to nonsense or frameshift changes. We show examples of protein modeling changes that occurred as a result of ZEB2 gene defects. We also report a novel pathogenic variant in exon 8 in a 5-year-old female proband with MWS. This review further explores other genes predicted to be interacting with the ZEB2 gene and their predicted gene-gene molecular interactions with protein binding effects on embryonic multi-system development such as craniofacial, spine, brain, kidney, cardiovascular, and hematopoiesis.

Unilateral progressive anterior iris adhesions in Mowat-Wilson syndrome: a new ocular finding

Ocular associations in Mowat-Wilson syndrome (MWS) are rare. Those involving the anterior segment are scarce in the literature. We describe a child with genetic confirmation of MWS that presented with acquired onset of unilateral anterior iris adhesions with no known trauma.