Mowat-Wilson Syndrome

Mowat-Wilson syndrome (MOWS) is a rare congenital disease caused by haploinsufficiency of ZEB2, encoding a transcription factor required for neurodevelopment. MOWS is characterized by intellectual disability, epilepsy, typical facial phenotype and other anomalies, such as short stature, Hirschsprung disease, brain and heart defects. Despite some recognizable features, MOWS rarity and phenotypic variability may complicate its diagnosis, particularly in the neonatal period. In order to define a novel diagnostic biomarker for MOWS, we determined the genome-wide DNA methylation profile of DNA samples from 29 individuals with confirmed clinical and molecular diagnosis. Through multidimensional scaling and hierarchical clustering analysis, we identified and validated a DNA methylation signature involving 296 differentially methylated probes as part of the broader MOWS DNA methylation profile. The prevalence of hypomethylated CpG sites agrees with the main role of ZEB2 as a transcriptional repressor, while differential methylation within the ZEB2 locus supports the previously proposed autoregulation ability. Correlation studies compared the MOWS cohort with 56 previously described DNA methylation profiles of other neurodevelopmental disorders, further validating the specificity of this biomarker. In conclusion, MOWS DNA methylation signature is highly sensitive and reproducible, providing a useful tool to facilitate diagnosis.

ZEB2 is a protein-coding gene belonging to a very restricted family of transcription factors. ZEB2 acts mainly as a transcription repressor, is expressed in various tissues and its role is fundamental for the correct development of the nervous system. The best-known clinical picture associated with ZEB2 mutations is Mowat-Wilson syndrome, caused mostly by haploinsufficiency and characterized by possible multi-organ malformations, dysmorphic features, intellectual disability, and epilepsy. In this study we report the generation of IGGi004-A and IGGi005-A, iPSC clones from two patients carrying different heterozygous mutations in ZEB2, which can be used for disease modelling, pathophysiological studies and therapeutics testing.

CD11c⁺ atypical B cells (ABCs) are an alternative memory B cell lineage associated with immunization, infection, and autoimmunity. However, the factors that drive the transcriptional program of ABCs have not been identified, and the function of this population remains incompletely understood. Here we identified candidate transcription factors associated with the ABC population based on a human tonsillar B cell single cell dataset. We identified CD11c⁺ B cells in mice with a similar transcriptomic signature to human ABCs, and using an optimized CRISPR-Cas9 knockdown screen, we observed that loss of zinc finger E-box binding homeobox 2 (Zeb2) impaired ABC formation. Furthermore, ZEB2 haplo-insufficient Mowat Wilson syndrome (MWS) patients have decreased circulating ABCs in the blood. In Cd23^Cre/+Zeb2^fl/fl mice with impaired ABC formation, ABCs were dispensable for efficient humoral responses after Plasmodium sporozoite immunization but were required to control recrudescent blood-stage malaria. Immune phenotyping revealed that ABCs drive optimal T follicular helper (Tfh) cell formation and germinal center (GC) responses and they reside at the red/white pulp border likely permitting better access to pathogen antigens for presentation. Collectively, our study shows that ABC formation is dependent upon Zeb2, and these cells can limit recrudescent infection by sustaining GC reactions.