A Novel WAC Loss of Function Mutation in an Individual Presenting with Encephalopathy Related to Status Epilepticus during Sleep (ESES)

Complimentary vertebrate Wac models exhibit phenotypes relevant to DeSanto-Shinawi Syndrome

Monogenic syndromes are associated with neurodevelopmental changes that result in cognitive impairments, neurobehavioral phenotypes including autism and attention deficit hyperactivity disorder (ADHD), and seizures. Limited studies and resources are available to make meaningful headway into the underlying molecular mechanisms that result in these symptoms. One such example is DeSanto-Shinawi Syndrome (DESSH), a rare disorder caused by pathogenic variants in the WAC gene. Individuals with DESSH syndrome exhibit a recognizable craniofacial gestalt, developmental delay/intellectual disability, neurobehavioral symptoms that include autism, ADHD, behavioral difficulties and seizures. However, no thorough studies from a vertebrate model exist to understand how these changes occur. To overcome this, we developed both murine and zebrafish Wac/wac deletion mutants and studied whether their phenotypes recapitulate those described in individuals with DESSH syndrome. We show that the two Wac models exhibit craniofacial and behavioral changes, reminiscent of abnormalities found in DESSH syndrome. In addition, each model revealed impacts to GABAergic neurons and further studies showed that the mouse mutants are susceptible to seizures, changes in brain volumes that are different between sexes and relevant behaviors. Finally, we uncovered transcriptional impacts of Wac loss of function that will pave the way for future molecular studies into DESSH. These studies begin to uncover some biological underpinnings of DESSH syndrome and elucidate the biology of Wac, with advantages in each model.

The Phenotypic Spectrum of Desanto-Shinawi Syndrome: A Comparative Report of the First Reported Case in Turkey

DeSanto-Shinawi syndrome (DESSH, OMIM #616708) is a rare genetic disorder caused by pathogenic variants in the WAC gene. This syndrome is characterized by a wide range of physical and neurological symptoms including dysmorphic features, developmental delay, intellectual disability, and behavioral abnormalities. DESSH was described by DeSanto in 2015, and since then, only a few dozen cases have been reported worldwide. Recent research has focused on identifying the underlying genetic cause of the syndrome as well as exploring potential treatments. In this report, we describe a female case who had dysmorphic features including long palpebral fissures, depressed nasal root, mild bulbous nasal tip, thin upper lip, hypertrichosis, short fingers, and intellectual disability, speech delay, and motor retardation. In addition, she had behavioral abnormalities such as agitation, anxiety, and attention deficit hyperactivity disorder (ADHD). Clinical exome sequencing showed a pathogenic heterozygous nonsense variant in exon 13 of the WAC gene c.1837C>T, p.(Arg613Ter) with de novo inheritance. To the best of our knowledge, this is the first case of DESSH reported from Turkey. We aimed to report this rare syndrome and compare the clinical findings of our case with previously reported cases in the literature.

Continuous Spike-Waves during Slow Sleep Today: An Update

In the context of childhood epilepsy, the concept of continuous spike-waves during slow sleep (CSWS) includes several childhood-onset heterogeneous conditions that share electroencephalograms (EEGs) characterized by a high frequency of paroxysmal abnormalities during sleep, which have negative effects on the cognitive development and behavior of the child. These negative effects may have the characteristics of a clear regression or of a slowdown in development. Seizures are very often present, but not constantly. The above makes it clear why CSWS have been included in epileptic encephalopathies, in which, by definition, frequent EEG paroxysmal abnormalities have an unfavorable impact on cognitive functions, including socio-communicative skills, causing autistic features, even regardless of the presence of clinically overt seizures. Although several decades have passed since the original descriptions of the electroclinical condition of CSWS, there are still many areas that are little-known and deserve to be further studied, including the EEG diagnostic criteria, the most effective electrophysiological parameter for monitoring the role of the thalamus in CSWS pathogenesis, its long-term evolution, the nosographic location of Landau-Kleffner syndrome, standardized neuropsychological and behavioral assessments, and pharmacological and non-pharmacological therapies.

The genetic landscape of developmental and epileptic encephalopathy with spike-and-wave activation in sleep

OBJECTIVE

Epileptic Encephalopathy / Developmental Epileptic Encephalopathy with spike-and-wave activation in sleep (EE/DEE-SWAS) is defined as an epilepsy syndrome characterized by neurodevelopmental regression temporally related to the emergence of significant activation of spike-wave discharges in EEG during sleep. The availability of genetic testing has made it evident that monogenic and chromosomal abnormalities play an aetiological role in the development of EE/DEE-SWAS. We sought to review the literature to better understand the genetic landscape of EE/DEE-SWAS.

METHODS

In this systematic review, we reviewed cases of EE/DEE-SWAS associated with a genetic aetiology, collecting information related to the underlying aetiology, onset, management, and EEG patterns.

RESULTS

One hundred and seventy-two cases of EE/DEE-SWAS were identified. Genetic causes of note included pathogenic variants in GRIN2A, ZEB2, CNKSR2 and chromosome 17q21.31 deletions, each of which demonstrated unique clinical characteristics, EEG patterns, and age of onset. Factors identified to raise suspicion of a potential genetic aetiology included the presentation of DEE-SWAS and onset of SWAS under the age of five years. Treatment of EE/DEE-SWAS due to genetic causes was diverse, including a combination of anti-seizure medications, steroids, and other clinical strategies, with no clear consensus on a preferred or superior treatment. Data collected was significantly heterogeneous, with a lack of consistent use of neuropsychology testing, EEG patterns, or use of established clinical definitions.

CONCLUSIONS

Uniformity concerning the new definition of EE/DEE-SWAS, guidelines for management and more frequent genetic screening will be needed to guide best practices for the treatment of patients with EE/DEE-SWAS.

Structure-Function of the Human WAC Protein in GABAergic Neurons: Towards an Understanding of Autosomal Dominant DeSanto-Shinawi Syndrome

Dysfunction of the WW domain-containing adaptor with coiled-coil, WAC, gene underlies a rare autosomal dominant disorder, DeSanto-Shinawi syndrome (DESSH). DESSH is associated with facial dysmorphia, hypotonia, and cognitive alterations, including attention deficit hyperactivity disorder and autism. How the WAC protein localizes and functions in neural cells is critical to understanding its role during development. To understand the genotype-phenotype role of WAC, we developed a knowledgebase of WAC expression, evolution, human genomics, and structural/motif analysis combined with human protein domain deletions to assess how conserved domains guide cellular distribution. Then, we assessed localization in a cell type implicated in DESSH, cortical GABAergic neurons. WAC contains conserved charged amino acids, phosphorylation signals, and enriched nuclear motifs, suggesting a role in cellular signaling and gene transcription. Human DESSH variants are found within these regions. We also discovered and tested a nuclear localization domain that impacts the cellular distribution of the protein. These data provide new insights into the potential roles of this critical developmental gene, establishing a platform to assess further translational studies, including the screening of missense genetic variants in WAC. Moreover, these studies are essential for understanding the role of human WAC variants in more diverse neurological phenotypes, including autism spectrum disorder.

Patients with DeSanto-Shinawi syndrome: Further extension of phenotype from Italy

Here we describe three patients with neurodevelopmental disorders characterized by mild-to-moderate intellectual disability, mildly dysmorphic features, and hirsutism, all of which carry de novo sequence variants in the WW domain-containing adaptor of the coiled-coil (WAC) gene; two of these-c.167delA, p.(Asn56I1efs*136) and c.1746G>C, p.(Gln582His)-are novel pathogenic variants, and the third-c.1837C>T, p(Arg613*)-has been previously described. Diseases associated with WAC include DeSanto-Shinawi syndrome; to date, de novo heterozygous constitutional pathogenic WAC variants have caused a syndromic form of intellectual disability and mild dysmorphic features in 33 patients, yet potential associations with other clinical manifestations, such as oligomenorrhea and hyperandrogenism, remain unknown, because the phenotypic spectrum of the condition has not yet been delineated. The patient bearing the novel c.167delA WAC gene variant presented a normal psychomotor development, oligomenorrhea, hyperandrogenism, and hirsutism, and hirsutism was also observed in the patient with the c.1746G>C WAC gene variant. Hypertrichosis and hirsutism have been described in nine DeSanto-Shinawi patients, only in 17 of the 33 aforementioned patients thus far reported this aspect, and no hormonal-pattern data are available. In conclusion, we note that the pathogenic c.167delA WAC variant may be associated with a mild phenotype; and in addition to the neurodevelopmental problems nearly all DeSanto-Shinawi patients experience (i.e., intellectual disability and/or developmental delay), we recommend the addition of mild dysmorphic features, hirsutism, and hypertrichosis to this clinical presentation.

Phenotypic and Brain Imaging Findings Associated With a 10p Proximal Deletion Including the WAC Gene: Case Report and Literature Review

Microarray-based techniques are an important testing method in etiological studies of intellectual disability and autism spectrum disorder. Interstitial deletion in the p11-p12 region of chromosome 10 is rare, having been reported in just 12 cases to date. Intellectual disability associated with the WAC gene in this region is referred to as DeSanto-Shinawi syndrome . Although all individuals with p11-p12 region of chromosome 10 deletion share a common phenotype involving intellectual disability and dysmorphic features, individuals with DeSanto-Shinawi syndrome usually do not experience the cardiac and neurologic abnormalities or cryptorchidism associated with a 10p11-p12 deletion. With this case report, we aim to expand the phenotypic spectrum of 10p11-p12 deletion. Our patient was a 9-year-old boy with intellectual disability, autism symptoms, dysmorphic features, and behavioral abnormalities. He had no cardiac problems or neurologic symptoms such as hypotonia, feeding difficulties, or seizures. However, he presented cryptorchidism in addition to symptoms that are consistent with DeSanto-Shinawi syndrome. Array comparative genomic hybridization of genomic DNA isolated from a peripheral blood sample revealed a heterozygous deletion in 10p11.23-p12.1, which contains the WAC gene. We discuss our case in the context of a literature review of candidate genes. It is still difficult to establish genotype-phenotype correlations for neurologic, cardiac, and visual symptoms, and cryptorchidism, in individuals with a 10p11-p12 deletion. As more individuals are diagnosed with deletion in this chromosomal region, the associated phenotypes will become clearer.

Phenotypic comparison of patients affected with DeSanto-Shinawi syndrome: Point mutations in WAC gene versus a 10p12.1 microdeletion including WAC

Introduction

DeSanto‐Shinawi syndrome is a rare neurodevelopmental disorder caused by loss‐of‐function variants of WAC, located on chromosome 10p12.1. This syndrome is characterized by dysmorphic facial features, intellectual disability, and behavioral problems.

Case report

In this case report, we present a new deletion case and summarize the clinical data of previously reported individuals, comparing the similarities and differences between cases caused by point mutations versus those which are caused by deletions in the 10p region.

Conclusion

Some differential features could facilitate the diagnostic suspicion guiding the optimal diagnostic tests that should be requested in each case scenario.

Clinical and molecular characterization of five new individuals with WAC-related intellectual disability: Evidence of pathogenicity for a novel splicing variant

WAC-related intellectual disability (ID) is a rare genetic condition characterized by a spectrum of neurodevelopmental disorders of varying severity, including global developmental delay (GDD), ID, and autism spectrum disorder. Here, we describe five affected individuals, age range 9-20 years, and provide proof of pathogenicity of a novel splicing variant. All individuals presented with GDD, some degree of ID, and variable dysmorphism. Except for feeding difficulties, all patients were healthy without major congenital malformations or medical comorbidities. All individuals were heterozygous for de novo, previously unreported, loss of function variants in WAC. Three unrelated patients from different ethnic backgrounds shared the intronic variant c.381+4_381+7delAGTA, which was predicted to alter splicing and was initially classified as a variant of uncertain significance. Reverse transcription-polymerase chain reaction analysis from one patient's cells confirmed aberrant splicing of the WAC transcript resulting in premature termination and a truncated protein p.(Gly92Alafs*2). These functional studies and the identification of several nonrelated individuals provide sufficient evidence to classify this variant as pathogenic. The clinical description of these five individuals and the three novel variants expand the genotypic and phenotypic spectrum of this ultrarare disease.

Congenital heart defects associated with pathogenic variants in WAC gene: Expanding the phenotypic and genotypic spectrum of DeSanto-Shinawi syndrome

WAC-related intellectual disability, also known as DeSanto-Shinawi syndrome, is a rare autosomal dominant genetic disorder caused by pathogenic variants in WAC gene. This syndrome is characterized by developmental delay, intellectual disability, behavioral abnormalities, and dysmorphic facial features, including deep-set eyes, flat nasal bridge, bulbous nasal tip, and synophrys. Chromosomal deletions at 10p12p11 encompassing WAC gene have been described in patients with a similar phenotype, presenting with developmental delay, intellectual disability, visual impairments, abnormal behavior, and dysmorphic features. An important clinical difference between the two groups of patients, is that those with large deletions frequently present with congenital cardiac defects, which were rarely reported in patients with pathogenic variants in WAC. The genes underlying heart defects in patients with the deletion have not yet been fully clarified. Here, we describe two unrelated Portuguese patients with de novo pathogenic variants in WAC gene, previously unreported in the literature. Both patients present with microcephaly, developmental delay, intellectual disability, behavioral problems, and facial dysmorphisms. Interestingly, the youngest patient has a severe congenital cardiac malformation, showing that intragenic pathogenic WAC variants can also be associated with heart defects. Therefore, this report expands the phenotypic and genotypic spectrum of this rare syndrome and provides deeper insights by comparing the clinical features of our patients with previously reported cases.

Extending the phenotype of DeSanto-Shinawi syndrome: A case report and literature review

DeSanto-Shinawi syndrome (DESSH, OMIM #616708) is a rare autosomal dominant neurodevelopmental disorder caused by loss-of-function variants in the WAC gene. Affected individuals are characterized by neonatal hypotonia, developmental delay, intellectual disability, behavioral problems, and dysmorphism. Epilepsy is present in some of the patients with DESSH. By far, less than 30 affected individuals have been reported worldwide. Herein, we report a 9-year-old Chinese girl with molecularly substantiated DESSH with a de novo nonsense c. 1648C>T p.(Arg550*) variant identified in the WAC gene. Aside from developmental delay and the characteristic facial gestalt, our proband also exhibited tethered cord syndrome due to filar lipoma and left duplex kidney complicated with hydronephrosis, features not observed in any of the previously reported individuals with DESSH.

Differential Functional Changes of Nav1.2 Channel Causing SCN2A-Related Epilepsy and Status Epilepticus During Slow Sleep

Background: Nav1.2 encoded by the SCN2A gene is a brain-expressed voltage-gated sodium channel known to be associated with neurodevelopment disorders ranging from benign familial neonatal infantile seizures (BFIS) to developmental and epileptic encephalopathy (DEE) and autism spectrum disorder. Interestingly, status epilepticus during slow sleep (ESES), which aggravates cognitive impairment, has been found in SCN2A-related epilepsy. However, the functional features and the relationship between SCN2A and ESES have not been researched.

Method: We herein investigated the functional consequences of an unpublished de novo V911A and the other two published variants in patients with SCN2A-related disorder and ESES by whole-cell patch-clamp studies in transfected HEK293T cells.

Results: The unpublished V911A and published K1933M variants detected in patients with DEE exhibited a profound gain-of-functional (GOF) change. Another published BFIS variant S863F significantly reduced current density as a loss-of-functional (LOF) change. The refractory epilepsy in the patient with V911A was controlled by using the precise treatment of oxcarbazepine (OXC) since the age of 3 months. ESES was found at 18 months during the seizure-free period. We finally chose an aggressive treatment for eliminating ESES by using methylprednisolone combined with levetiracetam and nitrazepam instead of the precise treatment of OXC.

Conclusion: Both GOF and LOF variants in the SCN2A gene can lead to ESES among the phenotypes of DEE and BFIS. We should monitor the electroencephalogram regularly in the patients with SCN2A-related epilepsy even during their seizure-free period.

Self-limited focal epilepsy and childhood apraxia of speech with WAC pathogenic variants

Heterozygous pathogenic WAC variants cause Desanto-Shinawi syndrome; affected patients have dysmorphic features, developmental impairment and behavioral abnormalities. Seizures are reported in one quarter, including tonic-clonic, absence, and febrile seizures. This study aimed to better understand the phenotypic spectrum of epilepsy and development in Desanto-Shinawi syndrome. We identified four children with seizures and pathogenic WAC variants, including two siblings. All had global developmental impairment with language affected most severely; two had diagnoses of childhood apraxia of speech and two had autism spectrum disorder. Seizure onset age ranged from six months to 14 years. Seizures always occurred from sleep and were focal impaired awareness with motor features in three patients, with one having bilateral tonic-clonic seizures of suspected focal onset. Two patients had spontaneous seizure resolution without treatment, and the remaining two were well-controlled on monotherapy. EEG was normal in two patients; one had focal right frontal spikes in drowsiness and sleep while the last had independent centrotemporal spikes from both hemispheres, activated in sleep. All patients had heterozygous truncating pathogenic WAC variants, with negative parental testing. The findings in this cohort of patients suggest that epilepsy in Desanto-Shinawi syndrome is usually focal and self-limited, and may fall within the epilepsy-aphasia spectrum.

A Case of DeSanto-Shinawi Syndrome in Bahrain with a Novel Mutation

DeSanto-Shinawi syndrome is a rare genetic condition caused by loss-of-function mutation in WAC. It is characterized by dysmorphic features, intellectual disability, and behavioral abnormalities. In this case report, we describe the clinical features and genotype of a patient with a novel mutation 1346C > A in WAC. This patient's dysmorphic features include a prominent forehead, bulbous nasal tip, macroglossia, deep-set eyes, and malar hypoplasia. This patient also showed signs of intellectual disability and behavioral abnormalities such as night terrors. These findings are consistent with those described in earlier reports. Here, we report new findings of epilepsy and recurrent skin infections which had not been reported in prior studies.