Phenotype and genotype of 87 patients with Mowat-Wilson syndrome and recommendations for care

Mowat-Wilson syndrome in a Chinese population: A case series

Mowat-Wilson syndrome (MWS) is characterized clinically by a distinctive facial gestalt, intellectual disability, microcephaly, epilepsy, and nonobligatory congenital malformations such as Hirschsprung disease, urogenital anomalies, congenital heart disease, eye malformations. This article summarized the clinical features and molecular findings of 15 Chinese MWS patients. The results revealed a higher incidence of congenital heart disease in Chinese MWS patients compared to that previously reported in Caucasian cohorts, while the incidence of Hirschsprung disease and genitourinary malformation appeared to be lower. This suggests possible ethnicity-related modifying effects in the MWS phenotype.

Analysis of gene variants in the GASH/Sal model of epilepsy

Epilepsy is a complex neurological disorder characterized by sudden and recurrent seizures, which are caused by various factors, including genetic abnormalities. Several animal models of epilepsy mimic the different symptoms of this disorder. In particular, the genetic audiogenic seizure hamster from Salamanca (GASH/Sal) animals exhibit sound-induced seizures similar to the generalized tonic seizures observed in epileptic patients. However, the genetic alterations underlying the audiogenic seizure susceptibility of the GASH/Sal model remain unknown. In addition, gene variations in the GASH/Sal might have a close resemblance with those described in humans with epilepsy, which is a prerequisite for any new preclinical studies that target genetic abnormalities. Here, we performed whole exome sequencing (WES) in GASH/Sal animals and their corresponding controls to identify and characterize the mutational landscape of the GASH/Sal strain. After filtering the results, moderate- and high-impact variants were validated by Sanger sequencing, assessing the possible impact of the mutations by “in silico” reconstruction of the encoded proteins and analyzing their corresponding biological pathways. Lastly, we quantified gene expression levels by RT-qPCR. In the GASH/Sal model, WES showed the presence of 342 variations, in which 21 were classified as high-impact mutations. After a full bioinformatics analysis to highlight the high quality and reliable variants, the presence of 3 high-impact and 15 moderate-impact variants were identified. Gene expression analysis of the high-impact variants of Asb14 (ankyrin repeat and SOCS Box Containing 14), Msh3 (MutS Homolog 3) and Arhgef38 (Rho Guanine Nucleotide Exchange Factor 38) genes showed a higher expression in the GASH/Sal than in control hamsters. In silico analysis of the functional consequences indicated that those mutations in the three encoded proteins would have severe functional alterations. By functional analysis of the variants, we detected 44 significantly enriched pathways, including the glutamatergic synapse pathway. The data show three high-impact mutations with a major impact on the function of the proteins encoded by these genes, although no mutation in these three genes has been associated with some type of epilepsy until now. Furthermore, GASH/Sal animals also showed gene variants associated with different types of epilepsy that has been extensively documented, as well as mutations in other genes that encode proteins with functions related to neuronal excitability, which could be implied in the phenotype of the GASH/Sal. Our findings provide valuable genetic and biological pathway data associated to the genetic burden of the audiogenic seizure susceptibility and reinforce the need to validate the role of each key mutation in the phenotype of the GASH/Sal model.

Pai syndrome: a review

BACKGROUND

Pai syndrome is a rare idiopathic developmental condition characterized by midline craniofacial abnormalities. It was originally described as the presence of a median cleft lip, cutaneous polyps of the nasal mucosa and face, and midline lipomas of the central nervous system, mostly at the corpus callosum. However, there is great phenotypical variability and these characteristics are rarely all present at once.

OBJECTIVE

The aim of this review was to analyze the available evidence regarding Pai syndrome in order to better delineate this rare condition and its features.

METHODS

We analyzed the PubMed database using the words "Pai syndrome", "frontonasal dysplasia", "cleft lip", "nasal polyp", "facial polyp", and "corpus callosum lipoma", including reviews, case reports and case series.

CONCLUSION

There is no consensus regarding the diagnostic criteria of Pai syndrome up to date. It is usually diagnosed at birth, and its incidence is often underestimated. At present, the etiology of Pai syndrome is unknown. Several hypotheses regarding its genetic background have been made; however, there are not enough data yet to elucidate this point. An improved awareness could help in diagnosing the condition and performing the necessary investigations. These patients should have a multidisciplinary follow-up.

Mowat-Wilson syndrome: Generation of two human iPS cell lines (UUIGPi004A and UUIGPi005A) from siblings with a truncating ZEB2 gene variant

Mowat-Wilson syndrome (MWS) is a complex developmental syndrome caused by heterozygous mutations in the Zinc finger E-box-binding homeobox 2 gene (ZEB2). We generated the first human iPSC lines from primary fibroblasts of two siblings with MWS carrying a heterozygous ZEB2 stop mutation (c.1027C > T; p.Arg343*) using the Sendai virus reprogramming system. Both iPSC lines were free from reprogramming vector genes, expressed pluripotency markers and showed potential to differentiate into the three germ layers. Genetic analysis confirmed normal karyotypes and a preserved stop mutation. These iPSC lines will provide a useful resource to study altered neural lineage fate and neuropathophysiology in MWS.

ZEB2 in T-cells and T-ALL

The identification of the rare but recurrent t(2; 14)(q22; q32) translocation involving the ZEB2 locus in T-cell acute lymphoblastic leukemia, suggested that ZEB2 is an oncogenic driver of this high-risk subtype of leukemia. ZEB2, a zinc finger E-box homeobox binding transcription factor, is a master regulator of cellular plasticity and its expression is correlated with poor overall survival of cancer patients. Recent loss- and gain-of-function in the mouse revealed important roles of ZEB2 during different stages of hematopoiesis, including the T-cell lineage. Here, we summarize the roles of ZEB2 in T-cells, their development, and malignant transformation to T-ALL.

Fetal diagnosis of Mowat-Wilson syndrome by whole exome sequencing

Mowat-Wilson syndrome (MWS) is a complex genetic disorder associated with heterozygous variation in ZEB2. It is mainly characterized by moderate-to-severe intellectual disability, facial dysmorphism, epilepsy, and various malformations including Hirschsprung disease, corpus callosum anomalies, and congenital heart defects. It is rarely diagnosed prenatally and there is limited information available on the prenatal phenotype associated with MWS. Here we report the detection of a heterozygous de novo nonsense variant in ZEB2 by whole exome sequencing in a fetus with microphthalmia in addition to cardiac defects and typical MWS facial dysmorphism. As the prenatal phenotypic spectrum of MWS expands, the routine addition of fetal genomic testing particularly in the presence of multiple malformations will increase both the sensitivity and specificity of prenatal diagnostics.

[Clinical and genetic features of Mowat-Wilson syndrome: an analysis of 3 cases]

Mowat-Wilson syndrome (MWS) is a rare autosomal dominant genetic disease caused by zinc finger E-box-binding homeobox 2 (ZEB2) gene mutation and has various clinical manifestations including intellectual disability/global developmental delay, unusual facies and multiple congenital malformations. This article reports the clinical features and gene mutations of three children diagnosed with MWS by ZEB2 gene analysis. All three children had Hirschsprung disease and unusual facies. One child died of severe heart failure and pneumonia at the age of 4 months. Global developmental delay was not discovered by her parents due to her young age. The other two children had severe global developmental delay. All three children carried a de novo heterozygous nonsense mutation in the ZEB2 gene, among which c.756C>A (p.Y252X) had not been reported before. Such mutations produced truncated proteins and were highly pathogenic. MWS is presented with strong clinical and genetic heterogeneity. Clinicians should consider the possibility of MWS when a child has unusual facies of MWS, intellectual disability/global developmental delay and multiple congenital malformations. Gene detection helps to make a confirmed diagnosis.

Sleep in Mowat-Wilson Syndrome: a clinical and video-polysomnographic study

OBJECTIVE

Sleep disturbances are frequently reported in Mowat-Wilson Syndrome (MWS). The current study aimed to evaluate clinical and video-polysomnographic (VPSG) characteristics of the sleep architecture and abnormal electroencephalogram (EEG) patterns during sleep in MWS.

METHODS

Sixteen individuals with MWS (range 16 months-25 years), attending the Department of Child Neurology and Psychiatry of the University of Bologna, were included. The "Sleep Disturbances Scale for Children (SDSC)" questionnaire was administered to all parents of MWS patients, and all patients underwent a VPSG recording.

RESULTS

The analysis of the SDSC questionnaire revealed disturbances mainly at the sleep-wake transition and in initiating and maintaining sleep. Evaluation of sleep structure in MWS patients showed a significant reduction of total sleep time, an increase of wake after sleep onset and arousal index as compared to normal controls. An EEG pattern characterized by slowing of background activity and poverty of physiological sleep characterisitcs was observed in all patients. Moreover, in patients aged >7 years, anteriorly predominant spike and waves were observed, markedly activated by sleep configuring a sub-continuous or continuous activity.

CONCLUSION

Our data (both clinical and VPSG) documented the presence of significant and clinically relevant sleep disturbances in MWS patients. Moreover, we identified a characteristic age-dependent sleep EEG pattern that could provide a new element to assist in the management of MWS.

Mowat-Wilson Syndrome Presenting With Purpura Fulminans

Purpura fulminans is a rapidly progressive syndrome of intravascular thrombosis and hemorrhagic infarction of the skin. The most common infectious etiology is Neisseria meningitidis sepsis, and less commonly it has been documented as a complication of invasive Streptococcus pneumoniae In children who are otherwise healthy, splenic dysfunction is a significant predisposing factor for invasive pneumococcal infection. We present the case of a 10-month-old girl with a history of developmental delay, who developed an overwhelming infection complicated by purpura fulminans and was found to have previously undiagnosed Mowat-Wilson syndrome with anatomic asplenia. We propose screening patients with clinical features suggestive of Mowat-Wilson syndrome for asplenia to evaluate the need for additional preventive care.

Role of Zeb2/Sip1 in neuronal development

Zeb2 (Sip1, Zfhx1b) is a transcription factor that plays essential role in neuronal development. Sip1 mutation in humans was shown to cause Mowat-Wilson syndrome, a syndromic form of Hirschprung's disease. Affected individuals exhibit multiple severe neurodevelopmental defects. Zeb2 can act as both transcriptional repressor and activator. It controls expression of a wide number of genes that regulate various aspects of neuronal development. This review addresses the molecular pathways acting downstream of Zeb2 that cause brain development disorders.

Exome-first approach identified novel INDELs and gene deletions in Mowat-Wilson Syndrome patients

Mowat-Wilson syndrome (MWS) is characterized by severe intellectual disability, absent or impaired speech and microcephaly, with a gradual post-natal onset. The syndrome is often confused with other Angelman-like syndromes (ALS) during infancy, but in older children and adults, the characteristic facial gestalt of Mowat–Wilson syndrome allows it to be distinguished easily from ALS. We report two cases in which an exome-first approach of patients with MWS identified two novel deletions in the ZEB2 gene ranging from a 4 base deletion (case 1) to at least a 573 Kb deletion (case 2).

Incidental finding of pulmonary arterial sling during patent ductus arteriosus surgery in a patient with Mowat-Wilson syndrome

Mowat-Wilson syndrome is a genetic condition due to a mutation in the ZEB2 gene; it affects many systems including the cardiovascular system. The pulmonary arterial sling originates from a failure of development of the proximal portion of the left sixth aortic arch, resulting in an anomalous left pulmonary artery origin from the posterior wall of the right pulmonary artery and the left pulmonary artery crossing to the left lung between the trachea and the oesophagus. We present a 4-month-old infant with Mowat-Wilson syndrome and left pulmonary arterial sling, and discuss the association of these two rare conditions. Pulmonary arterial sling is significantly more frequent in patients with Mowat-Wilson syndrome than in the general population.