Successful treatment of drug-resistant status epilepticus in an adult patient with Mowat-Wilson syndrome: A case report

Further delineation and long-term evolution of electroclinical phenotype in Mowat Wilson Syndrome. A longitudinal study in 40 individuals

BACKGROUND

Epilepsy is a main feature of Mowat Wilson Syndrome (MWS), a congenital malformation syndrome caused by ZEB2 variants. The aim of this study was to investigate the long-term evolution of the electroclinical phenotype of MWS in a large population.

METHODS

Forty-individuals with a genetically confirmed diagnosis were enrolled. Three age groups were identified (t1 = 0-4; t2 = 5-12; t3 = >13 years); clinical data and EEG records were collected, analyzed, and compared for age group. Video-EEG recorded seizures were reviewed.

RESULTS

Thirty-six of 40 individuals had epilepsy, of whom 35/35 aged >5 years. Almost all (35/36) presented focal seizures at onset (mean age at onset 3.4 ± 2.3 SD) that persisted, reduced in frequency, in 7/22 individuals after the age of 13. Absences occurred in 22/36 (mean age at onset 7.2 ± 0.9 SD); no one had absences before 6 and over 16 years old. Paroxysmal interictal abnormalities in sleep also followed an age-dependent evolution with a significant increase in frequency at school age (p = 0.002) and a reduction during adolescence (p = 0.008). Electrical Status Epilepticus during Sleep occurred in 14/36 (13/14 aged 5-13 years old at onset). Seven focal seizure ictal video-EEGs were collected: all were long-lasting and more visible clinical signs were often preceded by prolonged electrical and/or subtle (erratic head and eye orientation) seizures. Valproic acid was confirmed as the most widely used and effective drug, followed by levetiracetam.

CONCLUSIONS

Epilepsy is a major sign of MWS with a characteristic, age-dependent, electroclinical pattern. Improvement with adolescence/adulthood is usually observed. Our data strengthen the hypothesis of a GABAergic transmission imbalance underlying ZEB2-related epilepsy.

Neurological Phenotype of Mowat-Wilson Syndrome

Mowat-Wilson Syndrome (MWS) (OMIM # 235730) is a rare disorder due to ZEB2 gene defects (heterozygous mutation or deletion). The ZEB2 gene is a widely expressed regulatory gene, extremely important for the proper prenatal development. MWS is characterized by a specific facial gestalt and multiple musculoskeletal, cardiac, gastrointestinal, and urogenital anomalies. The nervous system involvement is extensive and constitutes one of the main features in MWS, heavily affecting prognosis and life quality of affected individuals. This review aims to comprehensively organize and discuss the neurological and neurodevelopmental phenotype of MWS. First, we will describe the role of ZEB2 in the formation and development of the nervous system by reviewing the preclinical studies in this regard. ZEB2 regulates the neural crest cell differentiation and migration, as well as in the modulation of GABAergic transmission. This leads to different degrees of structural and functional impairment that have been explored and deepened by various authors over the years. Subsequently, the different neurological aspects of MWS (head and brain malformations, epilepsy, sleep disorders, and enteric and peripheral nervous system involvement, as well as developmental, cognitive, and behavioral features) will be faced one at a time and extensively examined from both a clinical and etiopathogenetic point of view, linking them to the ZEB2 related pathways.