Copy number variants at Williams–Beuren syndrome 7q11.23 region

Genetic Testing for Supravalvar Aortic Stenosis: What to Do When It Is Not Williams Syndrome

BACKGROUND

We aimed to describe the frequency and yield of genetic testing in supravalvar aortic stenosis (SVAS) following negative evaluation for Williams-Beuren syndrome (WS).

METHODS AND RESULTS

This retrospective cohort study included patients with SVAS at our institution who had a negative evaluation for WS from May 1991 to September 2021. SVAS was defined as (1) peak supravalvar velocity of ≥2 meters/second, (2) sinotubular junction or ascending aortic Z score <-2.0, or (3) sinotubular junction Z score <-1.5 with family history of SVAS. Patients with complex congenital heart disease, aortic valve disease as the primary condition, or only postoperative SVAS were excluded. Genetic testing and diagnoses were reported. Of 162 patients who were WS negative meeting inclusion criteria, 61 had genetic testing results available (38%). Chromosomal microarray had been performed in 44 of 61 and was nondiagnostic for non-WS causes of SVAS. Sequencing of 1 or more genes was performed in 47 of 61. Of these, 39 of 47 underwent ELN sequencing, 20 of 39 (51%) of whom had a diagnostic variant. Other diagnoses made by gene sequencing were Noonan syndrome (3 PTPN11, 1 RIT1), Alagille syndrome (3 JAG1), neurofibromatosis (1 NF1), and homozygous familial hypercholesterolemia (1 LDLR1). Overall, sequencing was diagnostic in 29 of 47 (62%).

CONCLUSIONS

When WS is excluded, gene sequencing for SVAS is high yield, with the highest yield for the ELN gene. Therefore, we recommend gene sequencing using a multigene panel or exome analysis. Hypercholesterolemia can also be considered in individuals bearing the stigmata of this disease.

Oral manifestations of nine individuals with Williams syndrome. A case series

AIMS

Williams syndrome (WS) is a congenital developmental disorder characterized, mainly, by distinctive facial features, cardiovascular anomalies, growth delay and a typical neurobehavioral profile. The oral manifestations have not been sufficiently described and, therefore, the aim of the current study was to present the clinical, radiographic and microbiological findings of individuals with WS.

METHODS AND RESULTS

A series of nine WS individuals (seven females) with mean age 21 years-old were evaluated. A complete intraoral clinical examination, a radiographic analysis using panoramic and cephalometric x-ray and a supra- and sub-gingival microbiological profiling were performed. We observed abnormal tooth morphology, excessive interdental spacing, congenitally missing permanent teeth and malocclusion. High levels of DMFT were observed and gingivitis was present in all subjects. Bacteria related to periodontal disease were detected in dental plaque. Three patients were classified with a gingival phenotype type I according to the Maynard and Wilson classification. The sella turcica bridging was a novel finding for this group of patients.

CONCLUSION

Due to the elevated prevalence of gingivitis, caries and malocclusion, a multidisciplinary approach including dental follow-ups should be the standard of care in WS patients.

Intrauterine phenotype features of fetuses with 7q11.23 microduplication syndrome

OBJECTIVE

To share our experience on prenatal diagnosis of 7q11.23 microduplication syndrome and to further delineate the fetal phenotypes of the syndrome.

METHODS

A retrospective study was conducted to evaluate seven cases of dup7q11.23 syndrome diagnosed prenatally by chromosomal microarray (CMA). Clinical data were reviewed, including maternal characteristics, indications for prenatal diagnosis, sonographic findings, CMA results, pregnancy outcomes and follow-ups.

RESULTS

Seven cases, including 2 pairs of MCDA twins, were prenatally identified with dup7q11.23 syndrome. The most common prenatal sonographic features were ventriculomegaly, low-lying conus medullaris, and dilated ascending aorta. All 7 fetuses presented with typical 7q11.23 duplications (1.40-1.55 Mb). Parental chromosome analysis was performed in four pairs of parents, and indicated that the duplications of Case 6 and 7 were inherited from their asymptomatic mother.

CONCLUSION

Our case series suggest that prenatal features of dup7q11.23 cases are diversified, with ventriculomegaly and low-lying conus medullaris being the most common intrauterine phenotypes. Additionally, cleft palate, dilated ascending aorta, and renal abnormalities were also observed, and should be taken into consideration in subsequent studies.

Early maturation and hyperexcitability is a shared phenotype of cortical neurons derived from different ASD-associated mutations

Autism Spectrum Disorder (ASD) is characterized mainly by social and sensory-motor abnormal and repetitive behavior patterns. Over hundreds of genes and thousands of genetic variants were reported to be highly penetrant and causative of ASD. Many of these mutations cause comorbidities such as epilepsy and intellectual disabilities (ID). In this study, we measured cortical neurons derived from induced pluripotent stem cells (iPSCs) of patients with four mutations in the genes GRIN2B, SHANK3, UBTF, as well as chromosomal duplication in the 7q11.23 region and compared them to neurons derived from a first-degree relative without the mutation. Using a whole-cell patch-clamp, we observed that the mutant cortical neurons demonstrated hyperexcitability and early maturation compared to control lines. These changes were characterized by increased sodium currents, increased amplitude and rate of excitatory postsynaptic currents (EPSCs), and more evoked action potentials in response to current stimulation in early-stage cell development (3-5 weeks post differentiation). These changes that appeared in all the different mutant lines, together with previously reported data, indicate that an early maturation and hyperexcitability may be a convergent phenotype of ASD cortical neurons.

Prenatal diagnosis of Williams-Beuren syndrome by ultrasound and chromosomal microarray analysis

Background

There are a few literature reports of prenatal ultrasound manifestations of Williams-Beuren syndrome. We aimed to explore the prenatal diagnosis of Williams-Beuren syndrome by ultrasound and chromosomal microarray analysis and describe the prenatal ultrasound performance of this syndrome.

Methods

In this retrospective study, we reported eight cases of Williams-Beuren syndrome diagnosed at our prenatal diagnostic center from 2016 to 2021. We systematically reviewed clinical data from these cases, including indications for invasive testing, sonographic findings, QF-PCR results, chromosomal microarray analysis results, and pregnancy outcomes.

Results

In this study, the common ultrasound features were ventricular septal defect (37.5%), intrauterine growth retardation (25%), and aortic coarctation (25%). Moreover, all patients were found to have a common deletion in the Williams-Beuren syndrome chromosome region at the 7q11.23 locus, which contained the elastin gene. Deletion sizes ranged from 1.42 to 2.07 Mb. Seven parents asked for termination of pregnancy, and one patient was lost to follow-up.

Conclusions

This study is the most extensive prenatal study using chromosomal microarray analysis technology for detailed molecular analysis of Williams-Beuren syndrome cases. We reported three cases combined with first-reported ultrasound manifestations. Case 1 was concomitant with multicystic dysplastic kidney and duodenal atresia combined with case 3. Notably, case 4 was combined with multiple cardiovascular malformations: Tetralogy of Fallot, right aortic arch, and supravalvar aortic stenosis. These manifestations expand the intrauterine ultrasound phenotype of Williams-Beuren syndrome in previous literature reports.

A Comparison of Adaptive Functioning Between Children With Duplication 7 Syndrome and Williams-Beuren Syndrome: A Pilot Investigation

Interstitial deletions of 7q11.23 cause the well-known Williams-Beuren Syndrome (WBS), while duplication of the same region leads to duplication 7 syndrome (Dup7). Children with WBS share a distinct neurobehavioral phenotype including mild to severe intellectual disability, severely impaired visual spatial abilities, relatively preserved verbal expressive skills, anxiety problems, enhanced social motivation (i.e., hypersociable behaviors) and socio-communicative problems. Children with Dup7 syndrome exhibit some "inverted" features when compared to those of individuals with WBS, such as reduced social motivation and impairment of expressive language. Direct comparison of WBS and Dup7 represents a unique opportunity for the neurobehavioral characterization of the 7q11.23 section. However, most of the available data come from qualitative analysis between different studies. To the best of our knowledge, there are no studies directly comparing features of two matched samples of individuals with WBS and Dup7 syndromes. In this pilot study, we compare the adaptive functioning - measured with the Vineland Adaptive Behavior Scales, Second Edition - of two relatively small samples of children with molecularly confirmed diagnosis of WBS and Dup7 matched for IQ and chronological age, with a particular attention to socialization domain and expressive subdomain. Contrary to our assumption, we have not found any significant difference on socialization domain and expressive subdomains. This pilot investigation suggests that, when matched for chronological age and cognitive level, children with WBS and Dup7 share more similarities than expected. The inverted features that emerge in clinical settings on expressive language and social motivation seem not to differently interfere with the daily abilities to communicate and socialize with meaningful others during daily lives. Differences highlighted by previous undirected comparisons could be due to general and non-specific factors such as cognitive level, which is more severely impaired in individuals with WBS than Dup7. Implications for assessment and treatment are discussed.

Partial CHARGE syndrome with bilateral retinochoroidal colobomas associated with 7q11.23 duplication syndrome: case report

Background

CHARGE syndrome is a relatively common cause of deafness and blindness resulting from failure to form the primordia of specific organs due to deficient contribution of neural crest cell derivatives. The majority of CHARGE syndrome cases are caused by heterozygous mutations in CHD7 on chromosome 8q21. Those with CHARGE syndrome without CHD7 mutation typically do not have an identified genetic defect. 7q11.23 duplication syndrome is associated with mild facial dysmorphism, heart defects, language delay, and autism spectrum disorder. In the current literature, 7q11.23 duplication has not been associated with CHARGE syndrome, retinochoroidal colobomas, or significant ear abnormalities.

Case presentation

We describe a patient with 7q11.23 duplication syndrome and clinical CHARGE syndrome with no variant in CHARGE-associated genes.

Conclusions

This case highlights the still incomplete understanding of the pathogenesis of CHARGE syndrome and raises the possibility of a dose-sensitive effect of genes in the 7q11.23 critical region on neural crest differentiation and fate.

Altered White Matter and microRNA Expression in a Murine Model Related to Williams Syndrome Suggests That miR-34b/c Affects Brain Development via Ptpru and Dcx Modulation

Williams syndrome (WS) is a multisystem neurodevelopmental disorder caused by a de novo hemizygous deletion of ~26 genes from chromosome 7q11.23, among them the general transcription factor II-I (GTF2I). By studying a novel murine model for the hypersociability phenotype associated with WS, we previously revealed surprising aberrations in myelination and cell differentiation properties in the cortices of mutant mice compared to controls. These mutant mice had selective deletion of Gtf2i in the excitatory neurons of the forebrain. Here, we applied diffusion magnetic resonance imaging and fiber tracking, which showed a reduction in the number of streamlines in limbic outputs such as the fimbria/fornix fibers and the stria terminalis, as well as the corpus callosum of these mutant mice compared to controls. Furthermore, we utilized next-generation sequencing (NGS) analysis of cortical small RNAs' expression (RNA-Seq) levels to identify altered expression of microRNAs (miRNAs), including two from the miR-34 cluster, known to be involved in prominent processes in the developing nervous system. Luciferase reporter assay confirmed the direct binding of miR-34c-5p to the 3'UTR of PTPRU-a gene involved in neural development that was elevated in the cortices of mutant mice relative to controls. Moreover, we found an age-dependent variation in the expression levels of doublecortin (Dcx)-a verified miR-34 target. Thus, we demonstrate the substantial effect a single gene deletion can exert on miRNA regulation and brain structure, and advance our understanding and, hopefully, treatment of WS.

Cardiovascular findings in Williams-Beuren Syndrome: Experience of a single center with 127 cases

Williams-Beuren syndrome (WBS) is a rare, microdeletion syndrome characterized by facial dysmorphisms, intellectual disability, a friendly personality, cardiovascular and other abnormalities. Cardiovascular defects (CVD) are among the most prevalent characteristics in WBS, being supravalvular aortic stenosis (SVAS) the most frequent, followed by peripheral pulmonary stenosis (PPS). A comprehensive retrospective review of medical records of 127 patients with molecular diagnosis of WBS, in a period of 20 years, was done to evaluate the incidence, the natural history of cardiovascular disease, and the need for surgical intervention, including heart transplantation (HT). A total of 94/127 patients presented with CVD. Of these 94 patients, 50% presented with SVAS and 22.3% needed heart surgery and/or cardiac catheterization including one that required HT due to severe SVAS-related heart failure at 19 years of age. The patient died in the postoperative period due to infectious complications. Cardiovascular problems are the major cause of sudden death in patients with WBS, who have a significantly higher mortality risk associated with surgical interventions. There is a higher risk for anesthesia-related adverse events and for major adverse cardiac events following surgery. End-stage heart failure due to myocardial ischemia has been described in WBS patients and it is important to consider that HT can become their only viable option. To our knowledge, the case mentioned here is the first HT reported in an adolescent with WBS. HT can be a viable therapeutic option in WBS patients with adequate evaluation, planning, and a multidisciplinary team to provide the required perioperative care and follow-up.

Genomic regions associated with microdeletion/microduplication syndromes exhibit extreme diversity of structural variation

Segmental duplications (SDs) are a class of long, repetitive DNA elements whose paralogs share a high level of sequence similarity with each other. SDs mediate chromosomal rearrangements that lead to structural variation in the general population as well as genomic disorders associated with multiple congenital anomalies, including the 7q11.23 (Williams-Beuren Syndrome, WBS), 15q13.3, and 16p12.2 microdeletion syndromes. Population-level characterization of SDs has generally been lacking because most techniques used for analyzing these complex regions are both labor and cost intensive. In this study, we have used a high-throughput technique to genotype complex structural variation with a single molecule, long-range optical mapping approach. We characterized SDs and identified novel structural variants (SVs) at 7q11.23, 15q13.3, and 16p12.2 using optical mapping data from 154 phenotypically normal individuals from 26 populations comprising five super-populations. We detected several novel SVs for each locus, some of which had significantly different prevalence between populations. Additionally, we localized the microdeletion breakpoints to specific paralogous duplicons located within complex SDs in two patients with WBS, one patient with 15q13.3, and one patient with 16p12.2 microdeletion syndromes. The population-level data presented here highlights the extreme diversity of large and complex SVs within SD-containing regions. The approach we outline will greatly facilitate the investigation of the role of inter-SD structural variation as a driver of chromosomal rearrangements and genomic disorders.

Functions of Gtf2i and Gtf2ird1 in the developing brain: transcription, DNA binding and long-term behavioral consequences

Gtf2ird1 and Gtf2i are two transcription factors (TFs) among the 28 genes deleted in Williams syndrome, and prior mouse models of each TF show behavioral phenotypes. Here we identify their genomic binding sites in the developing brain and test for additive effects of their mutation on transcription and behavior. GTF2IRD1 binding targets were enriched for transcriptional and chromatin regulators and mediators of ubiquitination. GTF2I targets were enriched for signal transduction proteins, including regulators of phosphorylation and WNT. Both TFs are highly enriched at promoters, strongly overlap CTCF binding and topological associating domain boundaries and moderately overlap each other, suggesting epistatic effects. Shared TF targets are enriched for reactive oxygen species-responsive genes, synaptic proteins and transcription regulators such as chromatin modifiers, including a significant number of highly constrained genes and known ASD genes. We next used single and double mutants to test whether mutating both TFs will modify transcriptional and behavioral phenotypes of single Gtf2ird1 mutants, though with the caveat that our Gtf2ird1 mutants, like others previously reported, do produce low levels of a truncated protein product. Despite little difference in DNA binding and transcriptome-wide expression, homozygous Gtf2ird1 mutation caused balance, marble burying and conditioned fear phenotypes. However, mutating Gtf2i in addition to Gtf2ird1 did not further modify transcriptomic or most behavioral phenotypes, suggesting Gtf2ird1 mutation alone was sufficient for the observed phenotypes.

Prenatal detection of a 7q11.21 microdeletion (517-605 kb): A variant with normal characteristics at birth (STROBE)

In the literature, 7q11 deletion was reported with various abnormalities. However, there were other genetic conditions combined with 7q11.21. It is necessary to have sufficient pure 7q11.21 microdeletions for classifying the pathogenic categories of variation.Chromosomal karyotyping analysis was performed on cultured amniotic fluid cells. Eighteen pregnant women took chromosomal microarray using prenatal amniotic fluid samples at our center by Affymetrix CytoScan750K_Array. We followed the outcome of these pregnancies and determined postnatal health conditions.Cytogenetic studies delineated that all patients had normal karyotypes. The exception was P17, who had 47, XN. Single nucleotide polymorphism array results showed 517 to 605 kb deletions of 7q11.21 (chr7: 64543313-65196780) in these cases. The microarray results were pure or combined 7q11.21 microdeletions. In 11 pure 7q11.21 microdeletions and 7 combined cases, there was no apparent abnormal phenotype associated with partial 7q11.21. Among them, only mothers of P10 and P17 decided to terminate the pregnancies due to 18 trisomy or ultrasound abnormal fetal strephenopodia. In the follow-up survey, the newborns had no apparent abnormalities.In this study, we described 11 pure and 7 combined 7q11.21 microdeletions associating with no apparent postnatal phenotypic abnormalities. From this study, we can learn that the partial 7q11.21 deletion (chr7: 64543313-65196780) might be benign and have no association with human disorders.

A New Stepwise Molecular Work-Up After Chorionic Villi Sampling in Women With an Early Pregnancy Loss

Objective: To explore the use of a new molecular work-up based on the stepwise use of Quantitative Fluorescence PCR (QF-PCR) extended to eight chromosomes and single nucleotide polymorphism array (SNP-array) in chorionic villi obtained by chorionic villi sampling (CVS) offered to women experiencing an early pregnancy loss.

Methods: During a 3-year period (January 2016–December 2018), CVS was offered to women experiencing an early pregnancy loss before the evacuation of the products of conception (POC) to retrieve chorionic villi, irrespective of the number of previous losses. A new molecular work-up was prospectively assayed encompassing a first QF-PCR round (with the 21, 18, 13, 7, X, and Y chromosomes), a second QF-PCR round (with the 15, 16, and 22 chromosomes), and a high resolution SNP-array in those cases with normal QF-PCR results. A control group in which POC were collected after surgical uterine evacuation was used to be compared with the intervention group.

Results: Around 459 women were enrolled in the intervention group (CVS) and 185 in the control group (POC after uterine evacuation). The QF-PCR testing success rates were significantly higher in the intervention group (98.5%: 452/459) as compared to the control group (74%: 109/147; p < 0.001), while the chromosomal anomaly rate at the two QF-PCR rounds was similar between the two groups: 52% (234/452) in the intervention and 42% (46/109) in the control group (p = 0.073). The SNP-array was performed in 202 QF-PCR normal samples of the intervention group and revealed 67 (33%) atypical chromosomal anomalies (>10 Mb), 5 (2.5%) submicroscopic pathogenic copy number variants, and 2 (1%) variant of uncertain significance (VOUS).

Conclusion: Eighty-two percent of women experiencing an early pregnancy loss opted for a CVS. The testing success rates were higher in the intervention group (CVS; 98%) as compared to the control group (POC; 74%). The overall yields were 52% by QF-PCR (including three complete hydatiform moles), and 16% by SNP-array, including 15% atypical chromosomal anomalies and 1.1% submicroscopic pathogenic copy number variants.

Rare and low frequency genomic variants impacting neuronal functions modify the Dup7q11.23 phenotype

BACKGROUND

7q11.23 duplication (Dup7) is one of the most frequent recurrent copy number variants (CNVs) in individuals with autism spectrum disorder (ASD), but based on gold-standard assessments, only 19% of Dup7 carriers have ASD, suggesting that additional genetic factors are necessary to manifest the ASD phenotype. To assess the contribution of additional genetic variants to the Dup7 phenotype, we conducted whole-genome sequencing analysis of 20 Dup7 carriers: nine with ASD (Dup7-ASD) and 11 without ASD (Dup7-non-ASD).

RESULTS

We identified three rare variants of potential clinical relevance for ASD: a 1q21.1 microdeletion (Dup7-non-ASD) and two deletions which disrupted IMMP2L (one Dup7-ASD, one Dup7-non-ASD). There were no significant differences in gene-set or pathway variant burden between the Dup7-ASD and Dup7-non-ASD groups. However, overall intellectual ability negatively correlated with the number of rare loss-of-function variants present in nervous system development and membrane component pathways, and adaptive behaviour standard scores negatively correlated with the number of low-frequency likely-damaging missense variants found in genes expressed in the prenatal human brain. ASD severity positively correlated with the number of low frequency loss-of-function variants impacting genes expressed at low levels in the brain, and genes with a low level of intolerance.

CONCLUSIONS

Our study suggests that in the presence of the same pathogenic Dup7 variant, rare and low frequency genetic variants act additively to contribute to components of the overall Dup7 phenotype.

High-throughput screening identifies histone deacetylase inhibitors that modulate GTF2I expression in 7q11.23 microduplication autism spectrum disorder patient-derived cortical neurons

Background

Autism spectrum disorder (ASD) is a highly prevalent neurodevelopmental condition affecting almost 1% of children, and represents a major unmet medical need with no effective drug treatment available. Duplication at 7q11.23 (7Dup), encompassing 26–28 genes, is one of the best characterized ASD-causing copy number variations and offers unique translational opportunities, because the hemideletion of the same interval causes Williams–Beuren syndrome (WBS), a condition defined by hypersociability and language strengths, thereby providing a unique reference to validate treatments for the ASD symptoms. In the above-indicated interval at 7q11.23, defined as WBS critical region, several genes, such as GTF2I, BAZ1B, CLIP2 and EIF4H, emerged as critical for their role in the pathogenesis of WBS and 7Dup both from mouse models and human studies.

Methods

We performed a high-throughput screening of 1478 compounds, including central nervous system agents, epigenetic modulators and experimental substances, on patient-derived cortical glutamatergic neurons differentiated from our cohort of induced pluripotent stem cell lines (iPSCs), monitoring the transcriptional modulation of WBS interval genes, with a special focus on GTF2I, in light of its overriding pathogenic role. The hits identified were validated by measuring gene expression by qRT-PCR and the results were confirmed by western blotting.

Results

We identified and selected three histone deacetylase inhibitors (HDACi) that decreased the abnormal expression level of GTF2I in 7Dup cortical glutamatergic neurons differentiated from four genetically different iPSC lines. We confirmed this effect also at the protein level.

Limitations

In this study, we did not address the molecular mechanisms whereby HDAC inhibitors act on GTF2I. The lead compounds identified will now need to be advanced to further testing in additional models, including patient-derived brain organoids and mouse models recapitulating the gene imbalances of the 7q11.23 microduplication, in order to validate their efficacy in rescuing phenotypes across multiple functional layers within a translational pipeline towards clinical use.

Conclusions

These results represent a unique opportunity for the development of a specific class of compounds for treating 7Dup and other forms of intellectual disability and autism.

7q11.23 Microduplication Syndrome: Clinical and Neurobehavioral Profiling

7q11.23 Microduplication (dup7q11.23) syndrome is a rare autosomal dominant disorder due to a recurring 1.5 to 1.8 Mb duplication of the Williams-Beuren Syndrome critical region. Dup7q11.23 has been associated with several neuro-behavioral characteristics such as low cognitive and adaptive functioning, expressive language impairment, anxiety problems and autistic features. In the present study, we analyze the clinical features of ten individuals in which array-CGH detected dup7q11.23, spanning from 1.4 to 2.1 Mb. The clinical characteristics associated with dup7q11.23 are discussed with respect to its reciprocal deletion. Consistent with previous studies, we confirm that individuals with dup7q11.23 syndrome do not have a homogeneous clinical profile, although some recurring dysmorphic features were found, including macrocephaly, prominent forehead, elongated palpebral fissures, thin lip vermilion and microstomia. Minor congenital malformations include patent ductus arteriosus, cryptorchidism and pes planus. A common finding is hypotonia and joint laxity, resulting in mild motor delay. Neuropsychological and psychodiagnostic assessment confirm that mild cognitive impairment, expressive language deficits and anxiety are recurring neurobehavioral features. New insights into adaptive, psychopathological and neurodevelopmental profiles are discussed.

An unusual combination of an atypical maternally inherited novel 0.3 Mb deletion in Williams-Beuren region and a de novo 22q11.21 microduplication in an infant with supravalvular aortic stenosis

Williams-Beuren syndrome (WBS) is a rare neurodevelopmental disorder characterized by supravalvular aortic stenosis (SVAS), intellectual disability, overfriendliness and dysmorphic features. It is typically caused by 1.5-1.8 Mb deletions on 7q11.23. The 22q11.21 microduplication syndrome has a variable phenotype and is frequently associated with congenital heart disease. Here we present a unique patient, carrying aberrations within both of the above syndrome regions, referred for possible diagnosis of WBS because of SVAS. The patient was a boy who died suddenly 47 days after birth, possibly due to cardiac complications. Genetic testing was carried out, including array Comparative Genomic Hybridization (aCGH), Fluorescence In situ Hybridization (FISH) and Multiplex Ligation-Dependent Probe Amplification (MLPA) showing that the proband was heterozygous for a novel and atypical 0.3 Mb deletion in WBS region (7q11.23) encompassing the ELN gene. In addition, he was found heterozygous for a 22q11.21 microduplication. Parental studies revealed that the 7q11.23 deletion was inherited from the mother who also exhibited a cardiovascular phenotype, however very mild. The same maternally inherited deletion was detected in one of the proband's siblings, born two years later with a less severe SVAS. The 22q11.2 microduplication was de novo in origin. Detection and investigation of atypical deletions within known syndrome regions are crucial for better genotype-phenotype correlations and more accurate characterization of critical regions. The combined effect of two different genetic defects - one in a known syndrome region and one with variable clinical significance, is valuable for revealing gene interactions and enabling more accurate predictions, especially in prenatal diagnosis.

Quantitative genome-wide association study of six phenotypic subdomains identifies novel genome-wide significant variants in autism spectrum disorder

Autism spectrum disorders (ASD) are highly heritable and are characterized by deficits in social communication and restricted and repetitive behaviors. Twin studies on phenotypic subdomains suggest a differing underlying genetic etiology. Studying genetic variation explaining phenotypic variance will help to identify specific underlying pathomechanisms. We investigated the effect of common variation on ASD subdomains in two cohorts including >2500 individuals. Based on the Autism Diagnostic Interview-Revised (ADI-R), we identified and confirmed six subdomains with a SNP-based genetic heritability h²_SNP = 0.2-0.4. The subdomains nonverbal communication (NVC), social interaction (SI), and peer interaction (PI) shared genetic risk factors, while the subdomains of repetitive sensory-motor behavior (RB) and restricted interests (RI) were genetically independent of each other. The polygenic risk score (PRS) for ASD as categorical diagnosis explained 2.3-3.3% of the variance of SI, joint attention (JA), and PI, 4.5% for RI, 1.2% of RB, but only 0.7% of NVC. We report eight genome-wide significant hits-partially replicating previous findings-and 292 known and novel candidate genes. The underlying biological mechanisms were related to neuronal transmission and development. At the SNP and gene level, all subdomains showed overlap, with the exception of RB. However, no overlap was observed at the functional level. In summary, the ADI-R algorithm-derived subdomains related to social communication show a shared genetic etiology in contrast to restricted and repetitive behaviors. The ASD-specific PRS overlapped only partially, suggesting an additional role of specific common variation in shaping the phenotypic expression of ASD subdomains.

Cardiac arrest after induction of anesthesia in a 2-month-old infant with undiagnosed Williams syndrome

A 2-month-old male infant presented for elective repair of inguinal hernias. His preoperative medical history and physical examination were unremarkable. During induction of anesthesia, the infant sustained an adverse cardiac event. The event was characterized by tachycardia, hypotension, and massive ST-segment elevation. Despite vigorous resuscitation, spontaneous hemodynamic stability could not be achieved and extracorporeal membrane oxygenation was required. A transthoracic echocardiogram revealed severe hypoplasia of the ascending aorta. As effective cardiac function did not recover and there was evidence of diffuse ischemic brain injury, life support was withdrawn. Genetic testing performed postoperatively was definitive for Williams syndrome.

Genetic factors contributing to autism spectrum disorder in Williams-Beuren syndrome

BACKGROUND

The hallmark of the neurobehavioural phenotype of Williams-Beuren syndrome (WBS) is increased sociability and relatively preserved language skills, often described as opposite to autism spectrum disorders (ASD). However, the prevalence of ASD in WBS is 6-10 times higher than in the general population. We have investigated the genetic factors that could contribute to the ASD phenotype in individuals with WBS.

METHODS

We studied four males and four females with WBS and a confirmed diagnosis of ASD by the Autism Diagnostic Interview-Revised. We performed a detailed molecular characterisation of the deletion and searched for genomic variants using exome sequencing.

RESULTS

A de novo deletion of 1.55 Mb (6 cases) or 1.83 Mb (2 cases) at 7q11.23 was detected, being in 7/8 patients of paternal origin. No common breakpoint, deletion mechanism or size was found. Two cases were hemizygous for the rare T allele at rs12539160 in MLXIPL, previously associated with ASD. Inherited rare variants in ASD-related or functionally constrained genes and a de novo nonsense mutation in the UBR5 gene were identified in six cases, with higher burden in females compared with males (p=0.016).

CONCLUSIONS

The increased susceptibility to ASD in patients with WBS might be due to additive effects of the common WBS deletion, inherited and de novo rare sequence variants in ASD-related genes elsewhere in the genome, with higher burden of deleterious mutations required for females, and possible hypomorphic variants in the hemizygous allele or cis-acting mechanisms on imprinting.

In vitro fertilization does not increase the incidence of de novo copy number alterations in fetal and placental lineages

Although chromosomal instability (CIN) is a common phenomenon in cleavage-stage embryogenesis following in vitro fertilization (IVF)^1-3, its rate in naturally conceived human embryos is unknown. CIN leads to mosaic embryos that contain a combination of genetically normal and abnormal cells, and is significantly higher in in vitro-produced preimplantation embryos as compared to in vivo-conceived preimplantation embryos⁴. Even though embryos with CIN-derived complex aneuploidies may arrest between the cleavage and blastocyst stages of embryogenesis^5,6, a high number of embryos containing abnormal cells can pass this strong selection barrier^7,8. However, neither the prevalence nor extent of CIN during prenatal development and at birth, following IVF treatment, is well understood. Here we profiled the genomic landscape of fetal and placental tissues postpartum from both IVF and naturally conceived children, to investigate the prevalence and persistence of large genetic aberrations that probably arose from IVF-related CIN. We demonstrate that CIN is not preserved at later stages of prenatal development, and that de novo numerical aberrations or large structural DNA imbalances occur at similar rates in IVF and naturally conceived live-born neonates. Our findings affirm that human IVF treatment has no detrimental effect on the chromosomal constitution of fetal and placental lineages.

Genetic Basis for Congenital Heart Disease: Revisited: A Scientific Statement From the American Heart Association

This review provides an updated summary of the state of our knowledge of the genetic contributions to the pathogenesis of congenital heart disease. Since 2007, when the initial American Heart Association scientific statement on the genetic basis of congenital heart disease was published, new genomic techniques have become widely available that have dramatically changed our understanding of the causes of congenital heart disease and, clinically, have allowed more accurate definition of the pathogeneses of congenital heart disease in patients of all ages and even prenatally. Information is presented on new molecular testing techniques and their application to congenital heart disease, both isolated and associated with other congenital anomalies or syndromes. Recent advances in the understanding of copy number variants, syndromes, RASopathies, and heterotaxy/ciliopathies are provided. Insights into new research with congenital heart disease models, including genetically manipulated animals such as mice, chicks, and zebrafish, as well as human induced pluripotent stem cell-based approaches are provided to allow an understanding of how future research breakthroughs for congenital heart disease are likely to happen. It is anticipated that this review will provide a large range of health care-related personnel, including pediatric cardiologists, pediatricians, adult cardiologists, thoracic surgeons, obstetricians, geneticists, genetic counselors, and other related clinicians, timely information on the genetic aspects of congenital heart disease. The objective is to provide a comprehensive basis for interdisciplinary care for those with congenital heart disease.

The 7q11.23 Protein DNAJC30 Interacts with ATP Synthase and Links Mitochondria to Brain Development

Despite the known causality of copy-number variations (CNVs) to human neurodevelopmental disorders, the mechanisms behind each gene's contribution to the constellation of neural phenotypes remain elusive. Here, we investigated the 7q11.23 CNV, whose hemideletion causes Williams syndrome (WS), and uncovered that mitochondrial dysfunction participates in WS pathogenesis. Dysfunction is facilitated in part by the 7q11.23 protein DNAJC30, which interacts with mitochondrial ATP-synthase machinery. Removal of Dnajc30 in mice resulted in hypofunctional mitochondria, diminished morphological features of neocortical pyramidal neurons, and altered behaviors reminiscent of WS. The mitochondrial features are consistent with our observations of decreased integrity of oxidative phosphorylation supercomplexes and ATP-synthase dimers in WS. Thus, we identify DNAJC30 as an auxiliary component of ATP-synthase machinery and reveal mitochondrial maladies as underlying certain defects in brain development and function associated with WS.

Physical growth and development characteristics of children with Williams syndrome aged 0-24 months in Zhejiang Province

Background The objective of this study was to evaluate the physical growth and development characteristics of children with Williams syndrome (WS) aged 0-24 months, and provide help for early diagnosis of WS. Methods A total of 32 cases of children (17 males and 15 females) aged 0-24 months who were diagnosed with WS were enrolled between 2008 and 2017. These children were divided into four different groups: 1-6 months (six cases), 7-12 months (eight cases), 12-18 months (nine cases) and 19-24 months (nine cases). Meanwhile, a total of 32 healthy children (17 males and 15 females) were enrolled in the study from the Department of Health Care for physical examination in our hospital as the control group and matched with each divided group. Weight and height were measured, and meanwhile birth weight and height were also asked and recorded. Results There was no statistically significant difference in birth height between the two groups (p>0.05), and birth weight and the height and weight of the children with WS in the four groups were significantly lower than those of the children in the normal control (NC) group (p>0.05). When the corresponding age of WS children was compared to the Nine City Growth Curve Standards in China, 97% of cases were lagging behind in physical growth and development. Conclusions WS children often have the features of early slow physical growth, which provides certain help for the early diagnosis of WS. Therefore, for younger children, facial features combined with an accurate and objective physical growth assessment and ultrasonic cardiogram can greatly improve the screening rate.

Prevalence of chromosomal abnormalities identified by copy number variation sequencing in high-risk pregnancies, spontaneous abortions, and suspected genetic disorders

Objective

High-throughput sequencing based on copy number variation (CNV-seq) is commonly used to detect chromosomal abnormalities including aneuploidy. This study provides evidence for the prevalence of chromosomal abnormalities in target populations.

Methods

A total of 160 samples, including 83 high-risk pregnancies, 37 spontaneous abortions, and 40 suspected genetic disorders, were analyzed by CNV-seq. Relationships between the incidence of these chromosomal abnormalities and risk factors (e.g. advanced maternal age, abnormal pregnancy history, and family history of congenital disease) were further analyzed by subgroup.

Results

A total of 37 (44.6%) high-risk pregnancies, 25 (67.6%) spontaneous abortions, and 22 (55%) suspected genetic disorders had chromosomal abnormalities including aneuploidy and CNVs. There was an increased risk association between the prevalence of aneuploidy and pathogenic-relevant CNV in the fetus or abortive tissue and advanced maternal age. Moreover, a family history of congenital disease was also positively correlated with fetal chromosomal abnormalities in high-risk pregnancies.

Conclusion

A relatively high prevalence of chromosomal abnormalities was detected in high-risk pregnancies, spontaneous abortions, and suspected genetic disorders, indicating the importance of CNV detection in such populations.

Can Animal Models of Copy Number Variants That Predispose to Schizophrenia Elucidate Underlying Biology?

The diagnosis of schizophrenia rests on clinical criteria that cannot be assessed in animal models. Together with absence of a clear underlying pathology and understanding of what causes schizophrenia, this has hindered development of informative animal models. However, recent large-scale genomic studies have identified copy number variants (CNVs) that confer high risk of schizophrenia and have opened a new avenue for generation of relevant animal models. Eight recurrent CNVs have reproducibly been shown to increase the risk of schizophrenia by severalfold: 22q11.2(del), 15q13.3(del), 1q21(del), 1q21(dup), NRXN1(del), 3q29(del), 7q11.23(dup), and 16p11.2(dup). Five of these CNVs have been modeled in animals, mainly mice, but also rats, flies, and zebrafish, and have been shown to recapitulate behavioral and electrophysiological aspects of schizophrenia. Here, we provide an overview of the schizophrenia-related phenotypes found in animal models of schizophrenia high-risk CNVs. We also discuss strengths and limitations of the CNV models, and how they can advance our biological understanding of mechanisms that can lead to schizophrenia and can be used to develop new and better treatments for schizophrenia.

Decreased Neuron Density and Increased Glia Density in the Ventromedial Prefrontal Cortex (Brodmann Area 25) in Williams Syndrome

Williams Syndrome (WS) is a neurodevelopmental disorder caused by a deletion of 25–28 genes on chromosome 7 and characterized by a specific behavioral phenotype, which includes hypersociability and anxiety. Here, we examined the density of neurons and glia in fourteen human brains in Brodmann area 25 (BA 25), in the ventromedial prefrontal cortex (vmPFC), using a postmortem sample of five adult and two infant WS brains and seven age-, sex- and hemisphere-matched typically developing control (TD) brains. We found decreased neuron density, which reached statistical significance in the supragranular layers, and increased glia density and glia to neuron ratio, which reached statistical significance in both supra- and infragranular layers. Combined with our previous findings in the amygdala, caudate nucleus and frontal pole (BA 10), these results in the vmPFC suggest that abnormalities in frontostriatal and frontoamygdala circuitry may contribute to the anxiety and atypical social behavior observed in WS.

Exome sequencing of 85 Williams-Beuren syndrome cases rules out coding variation as a major contributor to remaining variance in social behavior

BACKGROUND

Large, multigenic deletions at chromosome 7q11.23 result in a highly penetrant constellation of physical and behavioral symptoms known as Williams-Beuren syndrome (WS). Of particular interest is the unusual social-cognitive profile evidenced by deficits in social cognition and communication reminiscent of autism spectrum disorders (ASD) that are juxtaposed with normal or even relatively enhanced social motivation. Interestingly, duplications in the same region also result in ASD-like phenotypes as well as social phobias. Thus, the region clearly regulates human social motivation and behavior, yet the relevant gene(s) have not been definitively identified.

METHOD

Here, we deeply phenotyped 85 individuals with WS and used exome sequencing to analyze common and rare variation for association with the remaining variance in social behavior as assessed by the Social Responsiveness Scale.

RESULTS

We replicated the previously reported unusual juxtaposition of behavioral symptoms in this new patient collection, but we did not find any new alleles of large effect in the targeted analysis of the remaining copy of genes in the Williams syndrome critical region. However, we report on two nominally significant SNPs in two genes that have been implicated in the cognitive and social phenotypes of Williams syndrome, BAZ1B and GTF2IRD1. Secondary discovery driven explorations focusing on known ASD genes and an exome wide scan do not highlight any variants of a large effect.

CONCLUSIONS

Whole exome sequencing of 85 individuals with WS did not support the hypothesis that there are variants of large effect within the remaining Williams syndrome critical region that contribute to the social phenotype. This deeply phenotyped and genotyped patient cohort with a defined mutation provides the opportunity for similar analyses focusing on noncoding variation and/or other phenotypic domains.

7q11.23 microduplication syndrome: neurophysiological and neuroradiological insights into a rare chromosomal disorder

BACKGROUND

The phenotypical consequence of the heterozygous chromosome 7q11.23 interstitial microdeletion is the Williams-Beuren syndrome, a very well-known genetic multi-systemic disorder. Much less is known about the reverse condition, the heterozygous interstitial microduplication of 7q11.23 region. The first molecular cytogenetic description was published in 2005, and only after several years were the reported patients numerous enough to attempt a description of a common phenotype.

METHOD

By using a broad multidisciplinary approach, we investigated 12 patients with this rare genetic anomaly. Ten of them harboured the duplication of the classical Williams-Beuren syndrome region and two a slightly larger duplication. Upon a detailed description of the clinical and psychological features, we used electroencephalography and magnetic resonance imaging to explore neurophysiological function and brain structures.

RESULTS

We analysed the clinical, psychological, neuroradiological and neurophysiological features of 12 yet-unpublished individuals affected by this rare genetic anomaly, focusing specifically on the last two aspects. Several structural abnormalities of the central nervous system were detected, like ventriculomegaly, hypotrophic cerebellum, hypotrophic corpus callosum and hypoplastic temporal lobes. Although only one of 12 individuals suffered from seizures during childhood, three others had abnormal electroencephalography findings prominent in the anterior brain regions, without any visible seizures to date.

CONCLUSION

Taken together, we enlarged the yet-underrepresented cohort in the literature of patients affected by 7q11.23 microduplication syndrome and shed further light on neuroradiological and neurophysiological aspects of this rare genetic syndrome.

Added value of chromosomal microarray analysis over karyotyping in early pregnancy loss: systematic review and meta-analysis

OBJECTIVE

To estimate the increased test success rate and incremental yield of chromosomal microarray analysis (CMA) over conventional karyotyping in detection of pathogenic copy number variants (CNVs) and variants of unknown significance (VOUS) in early pregnancy loss.

METHOD

This was a systematic review conducted in accordance with PRISMA criteria. All articles identified in PubMed, Ovid MEDLINE and Web of Science, between January 2000 and April 2017, that described CNVs in early pregnancy losses (up to 20 weeks) were included. Risk differences were pooled to estimate the incremental yield of CMA over karyotyping overall, and after stratification. In addition, test success rate, defined as the proportion of informative results, was compared in series in which CMA and karyotyping were performed concurrently.

RESULTS

Twenty-three studies, reporting on 5507 pregnancy losses up to 20 weeks with full data available, met the inclusion criteria for analysis. In the series in which CMA and karyotyping were performed concurrently, CMA showed a significant improvement in success rate, providing informative results in 95% (95% CI, 94-96%) of cases compared with karyotyping in which informative results were provided in 68% (95% CI, 66-70%) of cases. Combined data from reviewed studies revealed that incremental yields of CMA over karyotyping were 2% (95% CI, 1-2%) for pathogenic CNVs and 4% (95% CI, 3-6%) for VOUS. The most common pathogenic CNVs reported were 22q11.21 and 1p36.33 deletion.

CONCLUSION

In comparison with conventional karyotyping, CMA provides a significant increase in test success rate and incremental diagnostic yield in early pregnancy loss. Copyright © 2017 ISUOG. Published by John Wiley & Sons Ltd.

A novel dNTP-limited PCR and HRM assay to detect Williams-Beuren syndrome

BACKGROUND

Williams-Beuren syndrome (WBS) is caused by a microdeletion of chromosome arm 7q11.23. A rapid and inexpensive genotyping method to detect microdeletion on 7q11.23 needs to be developed for the diagnosis of WBS. This study describes the development of a new type of molecular diagnosis method to detect microdeletion on 7q11.23 based upon high-resolution melting (HRM).

METHODS

Four genes on 7q11.23 were selected as the target genes for the deletion genotyping. dNTP-limited duplex PCR was used to amplify the reference gene, CFTR, and one of the four genes respectively on 7q11.23. An HRM assay was performed on the PCR products, and the height ratio of the negative derivative peaks between the target gene and reference gene was employed to analyze the copy number variation of the target region.

RESULTS

A new genotyping method for detecting 7q11.23 deletion was developed based upon dNTP-limited PCR and HRM, which cost only 96 min. Samples from 15 WBS patients and 12 healthy individuals were genotyped by this method in a blinded fashion, and the sensitivity and specificity was 100% (95% CI, 0.80-1, and 95% CI, 0.75-1, respectively) which was proved by CytoScan HD array.

SIGNIFICANCE

The HRM assay we developed is an rapid, inexpensive, and highly accurate method for genotyping 7q11.23 deletion. It is potentially useful in the clinical diagnosis of WBS.

Elastin-driven genetic diseases

Elastic fibers provide recoil to tissues that undergo repeated deformation, such as blood vessels, lungs and skin. Composed of elastin and its accessory proteins, the fibers are produced within a restricted developmental window and are stable for decades. Their eventual breakdown is associated with a loss of tissue resiliency and aging. Rare alteration of the elastin (ELN) gene produces disease by impacting protein dosage (supravalvar aortic stenosis, Williams Beuren syndrome and Williams Beuren region duplication syndrome) and protein function (autosomal dominant cutis laxa). This review highlights aspects of the elastin molecule and its assembly process that contribute to human disease and also discusses potential therapies aimed at treating diseases of elastin insufficiency.

A postmortem stereological study of the amygdala in Williams syndrome

Perturbations to the amygdala have been observed in neurological disorders characterized by abnormalities in social behavior, such as autism and schizophrenia. Here, we quantitatively examined the amygdala in the postmortem human brains of male and female individuals diagnosed with Williams Syndrome (WS), a neurodevelopmental disorder caused by a well-defined deletion of ~ 26 genes, and accompanied by a consistent behavioral profile that includes profound hypersociability. Using unbiased stereological sampling, we estimated nucleus volume, number of neurons, neuron density, and neuron soma area in four major amygdaloid nuclei- the lateral nucleus, basal nucleus, accessory basal nucleus, and central nucleus- in a sample of five adult and two infant WS brains and seven age-, sex- and hemisphere-matched typically developing control (TD) brains. Boundaries of the four nuclei examined were drawn on Nissl-stained coronal sections as four separate regions of interest for data collection. We found that the lateral nucleus contains significantly more neurons in WS compared to TD. WS and TD do not demonstrate significant differences in neuron number in the basal, accessory basal, or central nuclei, and there are no significant differences between WS and TD in nuclei volume, neuron density, and neuron soma area in any of the four nuclei. A similarly designed study reported a decrease in lateral nucleus neuron number in autism, mirroring the opposing extremes of the two disorders in the social domain. These results suggest that the number of neurons in the lateral nucleus may contribute to pathological disturbances in amygdala function and sociobehavioral phenotype.

A Polymer Physics Investigation of the Architecture of the Murine Orthologue of the 7q11.23 Human Locus

In the last decade, the developments of novel technologies, such as Hi-C or GAM methods, allowed to discover that chromosomes in the nucleus of mammalian cells have a complex spatial organization, encompassing the functional contacts between genes and regulators. In this work, we review recent progresses in chromosome modeling based on polymer physics to understand chromatin structure and folding mechanisms. As an example, we derive in mouse embryonic stem cells the full 3D structure of the Bmp7 locus, a genomic region that plays a key role in osteoblastic differentiation. Next, as an application to Neuroscience, we present the first 3D model for the mouse orthologoue of the Williams-Beuren syndrome 7q11.23 human locus. Deletions and duplications of the 7q11.23 region generate neurodevelopmental disorders with multi-system involvement and variable expressivity, and with autism. Understanding the impact of such mutations on the rewiring of the interactions of genes and regulators could be a new key to make sense of their related diseases, with potential applications in biomedicine.

Congenital Heart Disease and Neurodevelopment: Clinical Manifestations, Genetics, Mechanisms, and Implications

Children with congenital heart disease (CHD) are at increased risk of neurodevelopmental disorders (NDDs) and psychiatric conditions. These include cognitive, adaptive, motor, speech, behavioural, and executive functioning deficits, as well as autism spectrum disorder and psychiatric conditions. Structural and functional neuroimaging have demonstrated brain abnormalities in young children with CHD before undergoing surgical repair, likely as a result of an in utero developmental insult. Surgical factors do not seem to play a significant role in neurodevelopmental outcomes. Specific genetic abnormalities, particularly copy number variants, have been increasingly implicated in both CHD and NDDs. Variations in genes involved in apolipoprotein E (APOE) production, the Wnt signalling pathway, and histone modification, as well as in the 1q21.1, 16p13.1-11, and 8p23.1 genetic loci, have been associated with CHD and NDDs and are important targets for future research. Understanding these associations is important for risk stratification, disease classification, improved screening, and pharmacologic management of individuals with CHD.

Williams-Beuren Syndrome and Congenital Lobar Emphysema: Uncommon Association with Common Pathology?

INTRODUCTION

Congenital lobar emphysema (CLE) and Williams-Beuren Syndrome are two rare conditions that have only been reported together in a single case study.

CASE PRESENTATION

We report another case of a male Caucasian newborn with nonspecific initial respiratory distress, with detection of CLE on repeat chest X-ray on Day 25 of life and concurrent ventricular septal defect, supravalvular aortic stenosis, and branch pulmonary stenosis, in whom a 7q11.23 deletion consistent with Williams-Beuren Syndrome was made.

CONCLUSION

A diagnosis of congenital lobar emphysema should prompt further screening for congenital heart disease and genetic deletion, and further research is needed to investigate the role of elastin gene mutation in the development of the neonatal lung.

Role of Splice Variants of Gtf2i, a Transcription Factor Localizing at Postsynaptic Sites, and Its Relation to Neuropsychiatric Diseases

We previously reported that various mRNAs were associated with postsynaptic density (PSD) purified from rat forebrain. Among the thousands of PSD-associated mRNAs, we highlight the biology of the general transcription factor II-I (Gtf2i) mRNA, focusing on the significance of its versatile splicing for targeting its own mRNA into dendrites, regulation of translation, and the effects of Gtf2i expression level as well as its relationship with neuropsychiatric disorders.

Genome wide array-CGH and qPCR analysis for the identification of genome defects in Williams' syndrome patients in Saudi Arabia

Background

Williams-Beuren Syndrome (WBS) is a rare neurodevelopmental disorder characterized by dysmorphic features, cardiovascular defects, cognitive deficits and developmental delay. WBS is caused by a segmental aneuploidy of chromosome 7 due to heterozygous deletion of contiguous genes at the long arm of chromosome 7q11.23. We aimed to apply array-CGH technique for the detection of copy number variants in suspected WBS patients and to determine the size of the deleted segment at chromosome 7q11.23 in correlation with the phenotype. The study included 24 patients referred to the CEGMR with the provisional diagnosis of WBS and 8 parents. The patients were subjected to conventional Cytogenetic (G-banding) analysis, Molecular Cytogenetic (Fluorescent In-Situ Hybridization), array-based Comparative Genomic Hybridization (array-CGH) and quantitative Real time PCR (qPCR) Techniques.

Results

No deletions were detected by Karyotyping, however, one patient showed unbalanced translocation between chromosome 18 and 19, the karyotype was 45,XX, der(19) t(18;19)(q11.1;p13.3)-18. FISH technique could detect microdeletion in chromosome 7q11.23 in 10/24 patients. Array-CGH and qPCR confirmed the deletion in all samples, and could detect duplication of 7q11.23 in three patients and two parents. Furthermore, the size of the deletion could be detected accurately by both array-CGH and qPCR techniques. Three patients not showing the 7q11.23 deletion were diagnosed by array-CGH to have deletion in chr9p13.1-p11.2, chr18p11.32-p11.21 and chr1p36.13.

Conclusion

Both FISH and array-CGH are reliable methods for the diagnosis of WBS; however, array-CGH has the advantage of detection of genome deletions/ duplications that cannot otherwise be detected by conventional cytogenetic techniques. Array-CGH and qPCR are useful for detection of deletion sizes and prediction of the interrupted genes and their impact on the disease phenotype. Further investigations are needed for studying the impact of deletion sizes and function of the deleted genes on chromosome 7q11.23.

Trial registration

ISRCTN ISRCTN73824458. MOCY-D-16-00041R1. Registered 28 September 2014. Retrospectively registered.

Neuron density is decreased in the prefrontal cortex in Williams syndrome

Williams Syndrome (WS) is a rare neurodevelopmental disorder associated with a hemideletion in chromosome 7, which manifests a distinct behavioral phenotype characterized by a hyperaffiliative social drive, in striking contrast to the social avoidance behaviors that are common in Autism Spectrum Disorder (ASD). MRI studies have observed structural and functional abnormalities in WS cortex, including the prefrontal cortex (PFC), a region implicated in social cognition. This study utilizes the Bellugi Williams Syndrome Brain Collection, a unique resource that comprises the largest WS postmortem brain collection in existence, and is the first to quantitatively examine WS PFC cytoarchitecture. We measured neuron density in layers II/III and V/VI of five cortical areas: PFC areas BA 10 and BA 11, primary motor BA 4, primary somatosensory BA 3, and visual area BA 18 in six matched pairs of WS and typically developing (TD) controls. Neuron density in PFC was lower in WS relative to TD, with layers V/VI demonstrating the largest decrease in density, reaching statistical significance in BA 10. In contrast, BA 3 and BA 18 demonstrated a higher density in WS compared to TD, although this difference was not statistically significant. Neuron density in BA 4 was similar in WS and TD. While other cortical areas were altered in WS, prefrontal areas appeared to be most affected. Neuron density is also altered in the PFC of individuals with ASD. Together these findings suggest that the PFC is targeted in neurodevelopmental disorders associated with sociobehavioral alterations. Autism Res 2017, 10: 99-112. © 2016 International Society for Autism Research, Wiley Periodicals, Inc.

Reciprocal Microduplication of the Williams-Beuren Syndrome Chromosome Region in a 9-Year-Old Omani Boy

BACKGROUND

Microdeletions of the 7q11.23 Williams-Beuren syndrome chromosome region (WBSCR) are reported with a frequency of 1 in 10,000, whereas microduplications of the region, although expected to occur at the same frequency, are not widely reported.

METHOD

We evaluated a 9-year old Omani boy for idiopathic intellectual disability using genetic methods, including multiplex ligation-dependent probe amplification (MLPA), for detection of microdeletions (P064-B3).

RESULTS

MLPA analysis revealed that the boy has a rare microduplication of the WBSCR. Prominent clinical features include global developmental delay with pronounced speech delay, dysmorphic facies, and autistic features.

CONCLUSION

Microduplications, in general, are reported at a lesser frequency, perhaps owing to their milder phenotype. Complete genetic assessment in children with idiopathic intellectual disability would help in identifying rare conditions such as duplication of the WBSCR.

Array CGH - A Powerful Tool in Molecular Diagnostic of Pathogenic Microdeletions - Williams-Beuren Syndrome - A Case Report

ABSTRACT: Williams-Beuren syndrome (WBS) (OMIM 194050) is caused by interstitial deletions or duplications of the 7q11.23 chromosomal region and characterised through a complex phenotype. We described a case diagnosed clinically and genetically confirmed through aCGH. Genetic assessment identified three microdeletions with a total size of 1.35 Mb located at 7q11.23. The deleted regions encompasses more than 30 genes including several protein coding genes such as ELN, LIMK1, FZDS, WBSCR22, WBSCR27, WBSCR28, STX1A, CLDN3, CLDN4, LAT2, ABHD11 or EIF4H .

Mouse Genetic Models of Human Brain Disorders

Over the past three decades, genetic manipulations in mice have been used in neuroscience as a major approach to investigate the in vivo function of genes and their alterations. In particular, gene targeting techniques using embryonic stem cells have revolutionized the field of mammalian genetics and have been at the forefront in the generation of numerous mouse models of human brain disorders. In this review, we will first examine childhood developmental disorders such as autism, intellectual disability, Fragile X syndrome, and Williams-Beuren syndrome. We will then explore psychiatric disorders such as schizophrenia and lastly, neurodegenerative disorders including Alzheimer’s disease and Parkinson’s disease. We will outline the creation of these mouse models that range from single gene deletions, subtle point mutations to multi-gene manipulations, and discuss the key behavioral phenotypes of these mice. Ultimately, the analysis of the models outlined in this review will enhance our understanding of the in vivo role and underlying mechanisms of disease-related genes in both normal brain function and brain disorders, and provide potential therapeutic targets and strategies to prevent and treat these diseases.

Williams-Beuren syndrome: pitfalls for diagnosis in limited resources setting

Patients with Williams–Beuren Syndrome can be recognized clinically, given the characteristic dysmorphism, intellectual disability, and behavior. We report on a Congolese boy with typical WBS facial characteristics. He suffered meningitis and coma at the age of 2 years then subsequently presented with profound intellectual disability and atypical behavior. The WBS was only made at age 8.2 years and confirmed with FISH testing and microarray‐CGH. The present report aims to warn clinicians that infections may associate and/or modify a genetic disease as this may be observed in developing countries given the prevalence of infectious diseases.

Differing Microdeletion Sizes and Breakpoints in Chromosome 7q11.23 in Williams-Beuren Syndrome Detected by Chromosomal Microarray Analysis

Williams-Beuren syndrome (WBS) manifests as supravalvular aortic stenosis, intellectual disability, developmental delay and characteristic facial features. The common WBS deletion region ranges from 1.55 to 1.84 Mb and primarily contains the ELN gene. We analyzed 10 patients diagnosed with 7q11.23 microdeletion syndrome by chromosomal microarray analysis. The clinical features of these patients varied from classic WBS to normal phenotype. All 10 patients exhibited different sizes and breakpoints of chromosome microdeletions ranging from 44 kb to 9.88 Mb. The hemizygosity of the ELN gene was detected in 7 patients, while a normal ELN gene was present in 3 other patients with small deletions. We observed that the phenotypic features of WBS varied in fetuses, children and adults, influenced by the genes, deletion size and breakpoint. Our findings provide more information on the genotype-phenotype correlations of WBS. However, further research is needed to explore the size and breakpoint effect and functions of the genes on chromosome 7q11.23.