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

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.

A novel variant of DeSanto-Shinawi Syndrome with joint manifestations

The clinical features associated with WAC haploinsufficiency include recognizable dysmorphic facial features, variable degrees of developmental delay and intellectual disability that were recently delineated as DeSanto-Shinawi syndrome (OMIM 616708). We describe a patient with DeSanto-Shinawi syndrome caused by a novel frameshift variant in WAC gene (NM_016628.4(WAC):c.1689del (p.Phe563Leufs*6)). As noted in cases previously reported, our patient phenotype included facial dysmorphism, intellectual disability, behavioral problems, feeding difficulties, hirsutism, constipation and astigmatism. She also had limited range of motion of joints since birth and Juvenile Idiopathic Arthritis diagnosed at eleven years old. Although in the last years some additional features were reported in DeSanto-Shinawi syndrome, joint manifestations have not been previously described. As limited range of motion of joints was reported since birth with no correlation with arthritis onset, it could be a new clinical feature. Polyarthritis in this patient can be only a coincidence, since there is a first degree relative with psoriasis, or might be related to WAC mutation. Indeed, WAC encodes a protein that plays a vital role in autophagy. It has already been demonstrated that WAC haploinsufficiency leads to increased autophagy and, according to different authors, increased autophagy may display a pathogenic role in several autoimmune disorders such as Rheumatoid Arthritis and Juvenile Idiopathic Arthritis. Thus, WAC haploinsufficiency may have contributed to autoimmune disorder in this patient.

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.