Challenges in clinical diagnosis of williams-beuren syndrome in sub-saharan africans: case reports from cameroon

Fluorescence in situ hybridization (FISH) as an irreplaceable diagnostic tool for Williams-Beuren syndrome in developing countries: a literature review

OBJECTIVE

The aim of this study was to sum up and characterize all Williams-Beuren syndrome cases diagnosed by fluorescence in situ hybridization (FISH) since its implementation, as well as to discuss FISH as a cost-effective methodology in developing countries.

DATA SOURCE

From January 1986 to January 2022, articles were selected using the databases in PubMed (Medline) and SciELO. The following terms were used: Williams syndrome and In Situ Hybridization, Fluorescence. Inclusion criteria included Williams-Beuren syndrome cases diagnosed by FISH with a stratified phenotype of each patient. Only studies written in English, Spanish, and Portuguese were included. Studies with overlapping syndromes or genetic conditions were excluded.

DATA SYNTHESIS

After screening, 64 articles were included. A total of 205 individuals with Williams-Beuren syndrome diagnosed by FISH were included and further analyzed. Cardiovascular malformations were the most frequent finding (85.4%). Supravalvular aortic stenosis (62.4%) and pulmonary stenosis (30.7%) were the main cardiac alterations described.

CONCLUSIONS

Our literature review reinforces that cardiac features may be the key to early diagnosis in Williams-Beuren syndrome patients. In addition, FISH may be the best diagnostic tool for developing nations that have limited access to new technologic resources.

In individuals with Williams syndrome, dysregulation of methylation in non-coding regions of neuronal and oligodendrocyte DNA is associated with pathology and cortical development

Williams syndrome (WS) is a neurodevelopmental disorder caused by a heterozygous micro-deletion in the WS critical region (WSCR) and is characterized by hyper-sociability and neurocognitive abnormalities. Nonetheless, whether and to what extent WSCR deletion leads to epigenetic modifications in the brain and induces pathological outcomes remains largely unknown. By examining DNA methylation in frontal cortex, we revealed genome-wide disruption in the methylome of individuals with WS, as compared to typically developed (TD) controls. Surprisingly, differentially methylated sites were predominantly annotated as introns and intergenic loci and were found to be highly enriched around binding sites for transcription factors that regulate neuronal development, plasticity and cognition. Moreover, by utilizing enhancer-promoter interactome data, we confirmed that most of these loci function as active enhancers in the human brain or as target genes of transcriptional networks associated with myelination, oligodendrocyte (OL) differentiation, cognition and social behavior. Cell type-specific methylation analysis revealed aberrant patterns in the methylation of active enhancers in neurons and OLs, and important neuron-glia interactions that might be impaired in individuals with WS. Finally, comparison of methylation profiles from blood samples of individuals with WS and healthy controls, along with other data collected in this study, identified putative targets of endophenotypes associated with WS, which can be used to define brain-risk loci for WS outside the WSCR locus, as well as for other associated pathologies. In conclusion, our study illuminates the brain methylome landscape of individuals with WS and sheds light on how these aberrations might be involved in social behavior and physiological abnormalities. By extension, these results may lead to better diagnostics and more refined therapeutic targets for WS.

Perspectives on the future of dysmorphology

The field of clinical genetics and genomics continues to evolve. In the past few decades, milestones like the initial sequencing of the human genome, dramatic changes in sequencing technologies, and the introduction of artificial intelligence, have upended the field and offered fascinating new insights. Though difficult to predict the precise paths the field will follow, rapid change may continue to be inevitable. Within genetics, the practice of dysmorphology, as defined by pioneering geneticist David W. Smith in the 1960s as "the study of, or general subject of abnormal development of tissue form" has also been affected by technological advances as well as more general trends in biomedicine. To address possibilities, potential, and perils regarding the future of dysmorphology, a group of clinical geneticists, representing different career stages, areas of focus, and geographic regions, have contributed to this piece by providing insights about how the practice of dysmorphology will develop over the next several decades.

The genetic determinants of oral diseases in Africa: The gaps should be filled

Oral diseases are a major health concern and are among the most prevalent diseases globally. This problem is becoming more prominent in the rapidly growing populations of Africa. It is well documented that Africa exhibits the most diverse genetic make-up in the world. However, little work has been conducted to understand the genetic basis of oral diseases in Africans. Oral health is often neglected and receives low prioritisation from funders and governments. The genetic determinants of highly prevalent oral diseases such as dental caries and periodontal disease, and regionally prevalent conditions such as oral cancer and NOMA, are largely under-researched areas despite numerous articles alluding to a high burden of these diseases in African populations. Therefore, this review aims to shed light on the significant gaps in research on the genetic and genomic aspects of oral diseases in African populations and highlights the urgent need for evidence-based dentistry, in tandem with the development of the dentist/scientist workforce.

Determination of craniofacial and dental characteristics of individuals with Williams-Beuren syndrome by using 3D facial scans and radiographs

BACKGROUND

Williams-Beuren syndrome (WBS) is caused by a microdeletion on chromosome 7q11-23 and clusters a variety of systemic affectations.

AIM

To investigate whether 3D facial scans can detect WBS by objectively addressing their craniofacial, skeletal and dental characteristics, compared with those of a non-affected control group.

MATERIALS AND METHODS

3D facial surface scans of 17 WBS individuals and 33 normal developing patients were analysed. Additionally, cephalometric and panoramic radiographs of subjects with WBS were compared with those of non-affected individuals.

RESULTS

The 3D surface scans showed significant facial differences around the nose and mouth area. The cephalometric aspects of individuals with WBS differed mainly at the lower incisor region. Additionally, hypoplastic tooth morphology seems to be more often present in WBS.

CONCLUSION

3D images are a non-invasive, efficient method to observe facial anomalies and facilitate an early diagnosis of WBS. Additionally, the analysis of the cephalometric and panoramic images revealed significant differences in dental characteristics. Together with early diagnosis through 3D images, these can help in the establishment of adequate medical, dental and orthodontic treatment planning.

Williams syndrome

Williams syndrome (WS) is a relatively rare microdeletion disorder that occurs in as many as 1:7,500 individuals. WS arises due to the mispairing of low-copy DNA repetitive elements at meiosis. The deletion size is similar across most individuals with WS and leads to the loss of one copy of 25-27 genes on chromosome 7q11.23. The resulting unique disorder affects multiple systems, with cardinal features including but not limited to cardiovascular disease (characteristically stenosis of the great arteries and most notably supravalvar aortic stenosis), a distinctive craniofacial appearance, and a specific cognitive and behavioural profile that includes intellectual disability and hypersociability. Genotype-phenotype evidence is strongest for ELN, the gene encoding elastin, which is responsible for the vascular and connective tissue features of WS, and for the transcription factor genes GTF2I and GTF2IRD1, which are known to affect intellectual ability, social functioning and anxiety. Mounting evidence also ascribes phenotypic consequences to the deletion of BAZ1B, LIMK1, STX1A and MLXIPL, but more work is needed to understand the mechanism by which these deletions contribute to clinical outcomes. The age of diagnosis has fallen in regions of the world where technological advances, such as chromosomal microarray, enable clinicians to make the diagnosis of WS without formally suspecting it, allowing earlier intervention by medical and developmental specialists. Phenotypic variability is considerable for all cardinal features of WS but the specific sources of this variability remain unknown. Further investigation to identify the factors responsible for these differences may lead to mechanism-based rather than symptom-based therapies and should therefore be a high research priority.

Williams–Beuren syndrome: a complete guide for oral healthcare

Introduction: Williams–Beuren syndrome is a rare, congenital, multisystem disorder, resulting from genetic alterations on chromosome 7q11.23. Characteristic features of WBS are the developmental, physical and mental abnormalities associated with it. Typical facial features and a spectrum of tooth disorders are associated with this condition. Cardiac and renal involvement may be so severe that sudden death during oral healthcare procedures is a possibility. Photophobia and hyperacusis further make dental treatment a challenge in these patients. Corpus: Routine dental treatment in the dental office pose a significant risk, depending upon the mental and physical compromise of the patient, thereby making hospital admission a safer approach. A multispeciality approach is necessary to provide effective and safe oral healthcare to such patients. This article provides undergraduates, residents, general dental practitioners, and specialists involved in oral healthcare with a comprehensive overview of the condition with emphasis on its genetic basis, pathology, clinical features, diagnosis, and management of general and oral health. Conclusion: Adequate knowledge regarding the various aspects of Williams–Beuren syndrome allows the oral health care student or specialist to plan and manage oral procedures safely and effectively. Specialist referral and multidisciplinary care may be considered when appropriate.

Diversity and dysmorphology

PURPOSE OF REVIEW

Dysmorphic features result from errors in morphogenesis frequently associated with genetic syndromes. Recognizing patterns of dysmorphic features is a critical step in the diagnosis and management of human congenital anomalies and genetic syndromes. This review presents recent developments in genetic syndromes and their related dysmorphology in diverse populations.

RECENT FINDINGS

Clinical findings in patients with genetic syndromes differ in their heterogeneity across different population groups. Some genetic syndromes have variable features in different ethnicities, in part due to specific background exam characteristics such as flat facial profiles or nasal differences; however, other genetic syndromes are similar across different ethnicities. Facial analysis technology is accurate in diagnosing genetic syndromes in populations around the world and is a powerful adjunct to conventional clinical examination. This accuracy also reinforces the concept that genetic syndromes can and should be diagnosed in any ethnicity.

SUMMARY

The increasing amount of data from studies on genetic syndromes in diverse populations is significantly improving our knowledge and approach to dysmorphic patients from various ethnic backgrounds. Optimal management of genetic syndromes requires early diagnosis, including in developing countries.

Williams-Beuren syndrome in diverse populations

Williams-Beuren syndrome (WBS) is a common microdeletion syndrome characterized by a 1.5Mb deletion in 7q11.23. The phenotype of WBS has been well described in populations of European descent with not as much attention given to other ethnicities. In this study, individuals with WBS from diverse populations were assessed clinically and by facial analysis technology. Clinical data and images from 137 individuals with WBS were found in 19 countries with an average age of 11 years and female gender of 45%. The most common clinical phenotype elements were periorbital fullness and intellectual disability which were present in greater than 90% of our cohort. Additionally, 75% or greater of all individuals with WBS had malar flattening, long philtrum, wide mouth, and small jaw. Using facial analysis technology, we compared 286 Asian, African, Caucasian, and Latin American individuals with WBS with 286 gender and age matched controls and found that the accuracy to discriminate between WBS and controls was 0.90 when the entire cohort was evaluated concurrently. The test accuracy of the facial recognition technology increased significantly when the cohort was analyzed by specific ethnic population (P-value < 0.001 for all comparisons), with accuracies for Caucasian, African, Asian, and Latin American groups of 0.92, 0.96, 0.92, and 0.93, respectively. In summary, we present consistent clinical findings from global populations with WBS and demonstrate how facial analysis technology can support clinicians in making accurate WBS diagnoses.

Noonan Syndrome in South Africa: Clinical and Molecular Profiles

Noonan Syndrome (NS) is a common autosomal dominant multisystem disorder, caused by mutations in more than 10 genes in the Ras/MAPK signaling pathway. Differential mutation frequencies are observed across populations. Clinical expressions of NS are highly variable and include short stature, distinctive craniofacial dysmorphism, cardiovascular abnormalities, and developmental delay. Little is known about phenotypic specificities and molecular characteristics of NS in Africa. The present study has investigated patients with NS in Cape Town (South Africa). Clinical features were carefully documented in a total of 26 patients. Targeted Next-Generation Sequencing (NGS) was performed on 16 unrelated probands, using a multigene panel comprising 14 genes: PTPN11, SOS1, RIT1, A2ML1, BRAF, CBL, HRAS, KRAS, MAP2K1, MAP2K2, NRAS, RAF1, SHOC2, and SPRED1. The median age at diagnosis was 4.5 years (range: 1 month−51 years). Individuals of mixed-race ancestry were most represented (53.8%), followed by black Africans (30.8%). Our cohort revealed a lower frequency of pulmonary valve stenosis (34.6%) and a less severe developmental milestones phenotype. Molecular analysis found variants predicted to be pathogenic in 5 / 16 cases (31.2%). Among these mutations, two were previously reported: MAP2K1-c.389A>G (p.Tyr130Cys) and PTPN11 - c.1510A>G (p.Met504Val); three are novel: CBL-c.2520T>G (p.Cys840Trp), PTPN11- c.1496C>T (p.Ser499Phe), and MAP2K1- c.200A>C (p.Asp67Ala). Molecular dynamic simulations indicated that novel variants identified impact the stability and flexibility of their corresponding proteins. Genotype-phenotype correlations showed that clinical features of NS were more typical in patients with variants in MAP2K1. This first application of targeted NGS for the molecular diagnosis of NS in South Africans suggests that, while there is no major phenotypic difference compared to other populations, the distribution of genetic variants in NS in South Africans may be different.

The 22q11.2 Deletion Syndrome in Congenital Heart Defects: Prevalence of Microdeletion Syndrome in Cameroon

BACKGROUND

The 22q11.2 deletion syndrome is amongst the most common microdeletion syndrome in humans. Its prevalence remains unknown in sub-Saharan Africa, and its clinical features are under-reported for people of African descent.

OBJECTIVE

We have investigated the prevalence of the 22q11.2 deletion syndrome in patients with congenital heart defects in Cameroon.

METHODS

A total of 70 of 100 cases of congenital cardiac malformation with echocardiographic evidence were examined prospectively and tested for the 22q11.2 deletion, using multiplex ligation-dependent probe amplification and fluorescence in situ hybridization.

RESULTS

Two of 70 patients (2.8%) were found to have 22q11.2 deletion. Both cases had conotruncal heart defects and exhibited extracardiac features of the 22q11.2 deletion syndrome that were either classical (e.g., puffy upper eyelids, bulbous tip of the nose) or less identifiable (telecanthus, hooding of eyelids and prominent nasal bridge).

CONCLUSIONS

The report shows that the prevalence of the 22q11.2 deletion syndrome in patients with heart malformations in Cameroon (2.8%) is similar to that of various world populations. The clinical phenotypes will contribute to the Global Atlas for dysmorphology. "Omics" technologies offer much promise in genetic/genomic screening of severe global health problems.

Towards a more representative morphology: clinical and ethical considerations for including diverse populations in diagnostic genetic atlases

An important gap exists in textbooks (or atlases) of dysmorphology used by health-care professionals to help diagnose genetic syndromes. The lack of varied phenotypic images in available atlases limits the utility of these atlases as diagnostic tools in globally diverse populations, causing geneticists difficulty in diagnosing conditions in individuals of different ancestral backgrounds who may present with variable morphological features. Proposals to address the underinclusion of images from diverse populations in existing atlases can take advantage of the Internet and digital photography to create new resources that take into account the broad global diversity of populations affected by genetic disease. Creating atlases that are more representative of the global population will expand resources available to care for diverse patients with these conditions, many of whom have been historically underserved by the medical system. However, such projects also raise ethical questions that are grounded in the complex intersection of imagery, medicine, history, and race and ethnicity. We consider here the benefits of producing such a resource while also considering ethical and practical concerns, and we offer recommendations for the ethical creation, structure, equitable use, and maintenance of a diverse morphological atlas for clinical diagnosis.Genet Med 18 11, 1069-1074.

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.

Diagnostic Path of a Genetic Disease: A Case of Williams-Beuren Syndrome in Burkina Faso

Williams-Beuren syndrome (WBS) is a rare neurodevelopmental disorder characterized by a set of somatic, psychological, and behavioral abnormalities, which is caused by a deletion of several genes. Herein we report a 6 year-old boy, who presented with mental retardation and psychological disorders. The result of the first clinical examination was poor, since it didn't detect any dysmorphic feature which is a major component for the clinical diagnosis of WBS. Despite the multidisciplinary and the multicenter approaches used, the diagnosis of WBS (deletion of chromosome band 7q11. 23) was established more than 3 years after the first medical consultation. Rare partial forms of WBS have been recently described and they are both clinically and genetically difficult to diagnose. Unfortunately, this disorder is still little known by health professionals.

Medical genetics and genomic medicine in Rwanda

Medical genetics and genomic medicine in Rwanda.