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.

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.

Rapid progression of aortic stenosis in a 3-month-old infant with bicuspid aortic valve and DeSanto-Shinawi syndrome

A 3-month-old female was diagnosed at 1 month of age with DeSanto-Shinawi syndrome (DSS) and bicuspid aortic valve with trivial stenosis. The aortic valve stenosis progressed to severe within 2 months and required balloon aortic valvuloplasty. This is the first case of aortic stenosis (AS) associated with DSS, and the syndrome may be the reason for the rapid worsening of AS in this case.

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.

Congenital Clavicular Pseudoarthosis-How to Differentiate It From the More Common Clavicular Fractures

Congenital pseudoarthrosis of the clavicle is a rare entity that can be confused for a traumatic injury. We present 4 cases of congenital clavicular pseudoarthrosis and discuss its imaging findings that can help differentiate it from the more common clavicular facture. We also reviewed its epidemiology, embryology, and management based on available and most recent literature.

DeSanto-Shinawi Syndrome: First Case in South America

Pathogenic variants in WAC are uncommon causes of developmental delay and neurobehavioral phenotypes. The clinical features associated with WAC haploinsufficiency include recognizable dysmorphic facial features that were recently delineated as DeSanto-Shinawi syndrome (DESSH; OMIM 616708). Additional clinical features include hypotonia, hearing and vision abnormalities, gastrointestinal problems, and behavioral difficulties. Here, we report a case of a 4-year-old Colombian male patient with typical dysmorphic facial features, developmental delay, hyperactivity, and recurrent respiratory infections. His immune workup revealed hypogammaglobulinemia, and clinical exome sequencing revealed a novel intronic variant in WAC (c.1437+1G>A). To the best of our knowledge, this is the first case of DESSH in South America, underlining the accumulating evidence of the significant role of WAC haploinsufficiency in neurobehavioral phenotypes. Although this report suggested the potential involvement of WAC in immune regulation, additional reports are required to confirm our observations.

Unraveling molecular pathways shared by Kabuki and Kabuki-like syndromes

Kabuki syndrome (KS) is a rare genetic syndrome characterized by a typical facial gestalt, variable degrees of intellectual disability, organ malformations, postnatal growth retardation and skeletal abnormalities. So far, KMT2D or KDM6A mutation has been identified as the main cause of KS, accounting for 56%-75% and 3%-8% of cases, respectively. Patients without mutations in 1 of the 2 causative KS genes are often referred to as affected by Kabuki-like syndrome. Overall, they represent approximately 30% of KS cases, pointing toward substantial genetic heterogeneity for this condition. Here, we review all currently available literature describing KS-like phenotypes (or phenocopies) associated with genetic variants located in loci different from KMT2D and KDM6A . We also report on a new KS phenocopy harboring a 5 Mb de novo deletion in chr10p11.22-11.21. An enrichment analysis aimed at identifying functional Gene Ontology classes shared by the 2 known KS causative genes and by new candidate genes currently associated with KS-like phenotypes primarily converges upon abnormal chromatin remodeling and transcriptional dysregulation as pivotal to the pathophysiology of KS phenotypic hallmarks. The identification of mutations in genes belonging to the same functional pathways of KMT2D and KDM6A can help design molecular screenings targeted to KS-like phenotypes.

A de novo 10p11.23-p12.1 deletion recapitulates the phenotype observed in WAC mutations and strengthens the role of WAC in intellectual disability and behavior disorders

Chromosomal microarray analysis has become a powerful diagnostic tool in the investigation of patients with intellectual disability leading to the discovery of dosage sensitive genes implicated in the manifestation of various genomic disorders. Interstitial deletions of the short arm of chromosome 10 represent rare genetic abnormalities, especially those encompassing the chromosomal region 10p11-p12. To date, only 10 postnatal cases with microdeletion of this region have been described, and all patients shared a common phenotype, including intellectual disability, abnormal behavior, distinct dysmorphic features, visual impairment, and cardiac malformations. WAC was suggested to be the main candidate gene for intellectual disability associated with 10 p11-p12 deletion syndrome. Here, we describe a new case of de novo 10p11.23-p12.1 microdeletion in a patient with intellectual disability, abnormal behavior, and distinct dysmorphic features. Our observation allows us to redefine the smallest region of overlap among patients reported so far, with a size of 80 Kb and which contains only the WAC gene. These findings strengthen the hypothesis that haploinsufficency of WAC gene might be likely responsible for intellectual disability and behavior disorders. Our data also led us to propose a clinical pathway for patients with this recognizable genetic syndrome depending on the facial dysmorphisms. © 2016 Wiley Periodicals, Inc.

De novo loss-of-function mutations in WAC cause a recognizable intellectual disability syndrome and learning deficits in Drosophila

Recently WAC was reported as a candidate gene for intellectual disability (ID) based on the identification of a de novo mutation in an individual with severe ID. WAC regulates transcription-coupled histone H2B ubiquitination and has previously been implicated in the 10p12p11 contiguous gene deletion syndrome. In this study, we report on 10 individuals with de novo WAC mutations which we identified through routine (diagnostic) exome sequencing and targeted resequencing of WAC in 2326 individuals with unexplained ID. All but one mutation was expected to lead to a loss-of-function of WAC. Clinical evaluation of all individuals revealed phenotypic overlap for mild ID, hypotonia, behavioral problems and distinctive facial dysmorphisms, including a square-shaped face, deep set eyes, long palpebral fissures, and a broad mouth and chin. These clinical features were also previously reported in individuals with 10p12p11 microdeletion syndrome. To investigate the role of WAC in ID, we studied the importance of the Drosophila WAC orthologue (CG8949) in habituation, a non-associative learning paradigm. Neuronal knockdown of Drosophila CG8949 resulted in impaired learning, suggesting that WAC is required in neurons for normal cognitive performance. In conclusion, we defined a clinically recognizable ID syndrome, caused by de novo loss-of-function mutations in WAC. Independent functional evidence in Drosophila further supported the role of WAC in ID. On the basis of our data WAC can be added to the list of ID genes with a role in transcription regulation through histone modification.

WAC loss-of-function mutations cause a recognisable syndrome characterised by dysmorphic features, developmental delay and hypotonia and recapitulate 10p11.23 microdeletion syndrome

BACKGROUND

Rare de novo mutations have been implicated as a significant cause of idiopathic intellectual disability. Large deletions encompassing 10p11.23 have been implicated in developmental delay, behavioural abnormalities and dysmorphic features, but the genotype-phenotype correlation was not delineated. Mutations in WAC have been recently reported in large screening cohorts of patients with intellectual disability or autism, but no full phenotypic characterisation was described.

METHODS

Clinical and molecular characterisation of six patients with loss-of-function WAC mutations identified by whole exome sequencing was performed. Clinical data were obtained by retrospective chart review, parental interviews, direct patient interaction and formal neuropsychological evaluation.

RESULTS

Five heterozygous de novo WAC mutations were identified in six patients. Three of the mutations were nonsense, and two were frameshift; all are predicted to cause loss of function either through nonsense-mediated mRNA decay or protein truncation. Clinical findings included developmental delay (6/6), hypotonia (6/6), behavioural problems (5/6), eye abnormalities (5/6), constipation (5/6), feeding difficulties (4/6), seizures (2/6) and sleep problems (2/6). All patients exhibited common dysmorphic features, including broad/prominent forehead, synophrys and/or bushy eyebrows, depressed nasal bridge and bulbous nasal tip. Posteriorly rotated ears, hirsutism, deep-set eyes, thin upper lip, inverted nipples, hearing loss and branchial cleft anomalies were also noted.

CONCLUSIONS

Our case series show that loss-of-function mutations in WAC cause a recognisable genetic syndrome characterised by a neurocognitive phenotype and facial dysmorphism. Our data highly suggest that WAC haploinsufficiency is responsible for most of the phenotypic features associated with deletions encompassing 10p11.23.

Bilateral congenital seudarthrosis of the clavicle. A clinical case

Congenital pseudarthrosis of the clavicle is a rare malformation in which the aetiology is still unclear. Bilateral involvement is exceptional. Although it is a congenital malformation, it may not be diagnosed until late childhood, with patients presenting with a painless deformity of the middle third of the clavicle in the absence of prior trauma. The treatment is controversial, and may be surgical, depending on the functional impact and aesthetics. A case of bilateral involvement is presented, together with a review of the relevant literature.

Prenatal and postnatal findings in a 10.6 Mb interstitial deletion at 10p11.22-p12.31

Interstitial deletion of the proximal short arm of chromosome 10 represents a rare genetic alteration. Literature review revealed that only 10 postnatal diagnosed clinical cases with deletions overlapping 10p12p11 were published until present. We report the first prenatal diagnosis and postnatal findings in a male fetus with a 10.6 Mb interstitial deletion of the short arm of chromosome 10 (10p11.22-p12.31).

Interstitial 10p11.23-p12.1 microdeletions associated with developmental delay, craniofacial abnormalities, and cryptorchidism

Cryptorchidism is the most common genital problem encountered in males and is associated with many chromosomal disorders; however, the genetic factors are mostly unknown. To delineate critical genes affecting testicular migration, we performed genotype-phenotype correlation in patients with deletions involving the proximal short arm of chromosome 10 (10p11-p12), a rare abnormality characterized by developmental delay, craniofacial abnormalities, and in some cases, cryptorchidism. Here we report on a male patient with developmental delay, mild craniofacial dysmorphism, bilateral cryptorchidism, and an 850-kb deletion, within the 10p11.2 region, involving three genes-MKX, ARMC4, and MPP7-as determined by array comparative genomic hybridization analysis. Comparison with four previously reported male patients with overlapping deletions revealed a 140-kb common region, containing the MKX gene, in association with cryptorchidism. The MKX gene is a member of the three amino acid loop extension (TALE) superclass of homeobox genes that is expressed in developing male gonads (male gonadal ridge and testis cords) in temporal relationship to SOX9, a critical regulator of sexual differentiation. Our results suggest that haploinsufficiency of the MKX gene may affect the developmental process during testis migration or serve as a genetic susceptibility locus for cryptorchidism. We propose that deletions of the proximal 10p represent a contiguous gene syndrome; therefore, patients may present with a complex phenotype, depending on the extent of the deletion.

Microdeletions and microduplications in patients with congenital heart disease and multiple congenital anomalies

OBJECTIVE

Multiple genetic syndromes are caused by recurrent chromosomal microdeletions or microduplications. The increasing use of high-resolution microarrays in clinical analysis has allowed the identification of previously undetectable submicroscopic copy number variants (CNVs) associated with genetic disorders. We hypothesized that patients with congenital heart disease and additional dysmorphic features or other anomalies would be likely to harbor previously undetected CNVs, which might identify new disease loci or disease-related genes for various cardiac defects.

DESIGN

Copy number analysis with single nucleotide polymorphism-based, oligonucleotide microarrays was performed on 58 patients with congenital heart disease and other dysmorphic features and/or other anomalies. The observed CNVs were validated using independent techniques and validated CNVs were further analyzed using computational algorithms and comparison with available control CNV datasets in order to assess their pathogenic potential.

RESULTS

Potentially pathogenic CNVs were detected in twelve of 58 patients (20.7%), ranging in size from 240 Kb to 9.6 Mb. These CNVs contained between 1 and 55 genes, including NRP1, NTRK3, MESP1, ADAM19, and HAND1, all of which are known to participate in cardiac development.

CONCLUSIONS

Genome-wide analysis in patients with congenital heart disease and additional phenotypes has identified potentially pathogenic CNVs affecting genes involved in cardiac development. The identified variant loci and the genes within them warrant further evaluation in similarly syndromic and nonsyndromic cardiac cohorts.

Genomic and clinical characteristics of six patients with partially overlapping interstitial deletions at 10p12p11

With the clinical implementation of genomic microarrays, the detection of cryptic unbalanced rearrangements in patients with syndromic developmental delay has improved considerably. Here we report the molecular karyotyping and phenotypic description of six new unrelated patients with partially overlapping microdeletions at 10p12.31p11.21 ranging from 1.0 to 10.6 Mb. The smallest region of overlap is 306 kb, which includes WAC gene, known to be associated with microtubule function and to have a role in cell division. Another patient has previously been described with a 10 Mb deletion, partially overlapping with our six patients. All seven patients have developmental delay and a majority of the patients have abnormal behaviour and dysmorphic features, including bulbous nasal tip, deep set eyes, synophrys/thick eyebrows and full cheeks, whereas other features varied. All patients also displayed various visual impairments and six out of seven patients had cardiac malformations. Taken together with the previously reported patient, our study suggests that the detected deletions may represent a new contiguous gene syndrome caused by dosage-sensitive genes that predispose to developmental delay.