ORIGINAL RESEARCH ARTICLEPurpose: Mowat-Wilson syndrome (MWS) is a rare intellectual disability/multiple congenital anomalies syndrome caused by heterozygous mutation of the ZEB2 gene. It is generally underestimated because its rarity and phenotypic variability sometimes make it difficult to recognize. Here, we aimed to better delineate the phenotype, natural history, and genotype-phenotype correlations of MWS. Methods:In a collaborative study, we analyzed clinical data for 87 patients with molecularly confirmed diagnosis. We described the prevalence of all clinical aspects, including attainment of neurodevelopmental milestones, and compared the data with the various types of underlying ZEB2 pathogenic variations.Results: All anthropometric, somatic, and behavioral features reported here outline a variable but highly consistent phenotype. By presenting the most comprehensive evaluation of MWS to date, we define its clinical evolution occurring with age and derive suggestions for patient management. Furthermore, we observe that its severity correlates with the kind of ZEB2 variation involved, ranging from ZEB2 locus deletions, associated with severe phenotypes, to rare nonmissense intragenic mutations predicted to preserve some ZEB2 protein functionality, accompanying milder clinical presentations. Conclusion:Knowledge of the phenotypic spectrum of MWS and its correlation with the genotype will improve its detection rate and the prediction of its features, thus improving patient care.

Purpose Mowat-Wilson syndrome (MWS) is a genetic disease characterized by distinctive facial features, moderate to severe intellectual disability and congenital malformations including Hirschsprung disease, genital and eye anomalies and congenital heart defects, caused by haploinsufficiency of the ZEB2 gene. To date, no characteristic pattern of brain dysmorphology in MWS has been defined. Methods Through brain MRI analysis, we delineate a neuroimaging phenotype in 54 MWS patients with a proven ZEB2 defect, compare it with the features identified in a thorough review of published cases, and evaluate genotype-phenotype correlations. Results 96% of patients had abnormal MRI. The most common features were anomalies of corpus callosum (79.6% of cases), hippocampal abnormalities (77.8%), enlargement of cerebral ventricles (68.5%), white matter abnormalities (reduction of thickness 40.7%, localized signal alterations 22.2%). Other consistent findings were large basal ganglia, cortical and cerebellar malformations. Most features were underrepresented in the literature. We also found ZEB2 variations leading to synthesis of a defective protein to be favourable for psychomotor development and some epilepsy features, but also associated with corpus callosum agenesis. Conclusion This study delineates the spectrum of brain anomalies in MWS and at the same time adds new insights in elucidating the role of ZEB2 in neurodevelopment.

Mowat-Wilson syndrome (MWS) is a genetic disease caused by heterozygous mutations or deletions of the ZEB2 gene and is characterized by distinctive facial features, epilepsy, moderate to severe intellectual disability, corpus callosum abnormalities and other congenital malformations. Epilepsy is considered a main manifestation of the syndrome, with a prevalence of about 70-75%. In order to delineate the electroclinical phenotype of epilepsy in MWS, we investigated epilepsy onset and evolution, including seizure types, EEG features, and response to anti-epileptic therapies in 22 patients with genetically confirmed MWS. Onset of seizures occurred at a median age of 14.5 months (range: 1-108 months). The main seizure types were focal and atypical absence seizures. In all patients the first seizure was a focal seizure, often precipitated by fever. The semiology was variable, including hypomotor, versive, or focal clonic manifestations; frequency ranged from daily to sporadic. Focal seizures were more frequent during drowsiness and sleep. In 13 patients, atypical absence seizures appeared later in the course of the disease, usually after the age of 4 years. Epilepsy was usually quite difficult to treat: seizure freedom was achieved in nine out of the 20 treated patients. At epilepsy onset, the EEGs were normal or showed only mild slowing of background activity. During follow-up, irregular, diffuse frontally dominant and occasionally asymmetric spike and waves discharges were seen in most patients. Sleep markedly activated these abnormalities, resulting in continuous or near-to-continuous spike and wave activity during slow wave sleep. Slowing of background activity and poverty of physiological sleep features were seen in most patients. Our data suggest that a distinct electroclinical phenotype, characterized by focal and atypical absence seizures, often preceded by febrile seizures, and age-dependent EEG changes, can be recognized in most patients with MWS.

This novel CACNA1A mutation adds to the number of mutations associated with a heterogeneous clinical picture in family members. This mutation might affect the interaction between the intracellular loops and the beta subunit, leading to a relatively rapid cell death. In order to explain the wide phenotypic variability observed in this family, it is hypothesised that additional genetic and environmental (hormonal) factors play a role in the pathophysiology of the disease.

Background: Sodium channel alpha 1 subunit gene, SCN1A, is the gene encoding the neuronal voltage-gated sodium channel ␣ 1 subunit (Na v 1.1) and is mutated in different forms of epilepsy. Mutations in this gene were observed in more than 70% of patients with severe myoclonic epilepsy of infancy (SMEI) and were also found in different types of infantile epileptic encephalopathy.Objective: To search for disease-causing mutations in SCN1A in patients with cryptogenic epileptic syndromes (ie, syndromes with an unknown cause).Design: Clinical characterization and molecular genetic analysis of a cohort of patients.