Search Results (7)

Background/Objectives: Congenital heart disease (CHD) occurs in ~1% of all live neonates globally, rendering it the most prevalent developmental anomaly affecting humans; this condition confers substantial infant morbidity and mortality worldwide. Although there is ample evidence to suggest a paramount genetic basis for CHD, the genetic etiologies underpinning the majority of CHD remain elusive. In the present study, SOX4 was selected as a significant candidate gene for human CHD, mainly because SOX4 is abundantly expressed in both human and murine hearts during embryogenesis, and the knockout of Sox4 in mice causes embryonic demise predominantly attributable to cardiovascular developmental defects. Methods: Sequencing analysis of SOX4 was fulfilled in 248 probands affected with various types of CHD and the available relatives of the identified variation carrier as well as 262 unrelated healthy individuals. Functional analysis of the mutant SOX4 protein was conducted by utilizing a dual-reporter gene system. Results: a novel heterozygous SOX4 variation, NM_003107.3:c.331G>T;p.(Glu111*), was discovered in a male proband with Coffin–Siris syndromic CHD. Genetic investigation of the proband’s available relatives revealed that the truncating variation co-segregated with the phenotype in the whole family. The nonsense variation was absent from 262 healthy controls. Functional analysis demonstrated that the Glu111*-mutant SOX4 lost transactivation on NKX2.5 and GATA4, two well-established genes that are causative factors for CHD. Moreover, the Glu111* mutation nullified the synergistic transactivation between SOX4 and TBX20, another CHD-causing gene. Conclusions: These findings support SOX4 as a causative gene accountable for familial Coffin–Siris syndromic CHD in humans. These findings may aid in developing personalized preventive and therapeutic strategies for patients with Coffin–Siris syndromic CHD. Full article

We present a case report of a 26-year-old female suffering from Coffin–Siris Syndrome, who underwent orthodontic treatment and surgery to solve her malocclusion and to improve her aesthetics and functional occlusion. Methods: The presurgical phase involved multibracket self-ligating attachments, namely a Damon prescription. The patient underwent maxillofacial surgery to correct the severe skeletal malocclusion and to relocate the bone bases to the right position. Post-surgical orthodontic treatment was performed to complete the alignment. Results: The patient’s aesthetics and functional abilities improved. Conclusions: Syndromic patients can undergo orthodontic treatment if comorbidities and collaboration allow it. The support and collaboration of families and psychotherapists must be considered, but clinical cases of syndromic patients can be faced and solved. Obviously, each syndromic patient is considered unique, and the risk–benefit ratio must be correctly assessed for each one. Full article

SOX4 is a transcription factor with pleiotropic functions required for different developmental processes, such as corticogenesis. As with all SOX proteins, it contains a conserved high mobility group (HMG) and exerts its function via interaction with other transcription factors, such as POU3F2. Recently, pathogenic SOX4 variants have been identified in several patients who had clinical features overlapping with Coffin–Siris syndrome. In this study, we identified three novel variants in unrelated patients with intellectual disability, two of which were de novo (c.79G>T, p.Glu27*; c.182G>A p.Arg61Gln) and one inherited (c.355C>T, p.His119Tyr). All three variants affected the HMG box and were suspected to influence SOX4 function. We investigated the effects of these variants on transcriptional activation by co-expressing either wildtype (wt) or mutant SOX4 with its co-activator POU3F2 and measuring their activity in reporter assays. All variants abolished SOX4 activity. While our experiments provide further support for the pathogenicity of SOX4 loss-of-function (LOF) variants as a cause of syndromic intellectual disability (ID), our results also indicate incomplete penetrance associated with one variant. These findings will improve classification of novel, putatively pathogenic SOX4 variants. Full article

KMT2A (Lysine methyltransferase 2A) is a member of the epigenetic machinery, encoding a lysine methyltransferase responsible for the transcriptional activation through lysine 4 of histone 3 (H3K4) methylation. KMT2A has a crucial role in gene expression, thus it is associated to pathological conditions when found mutated. KMT2A germinal mutations are associated to Wiedemann–Steiner syndrome and also in patients with initial clinical diagnosis of several other chromatinopathies (i.e., Coffin–Siris syndromes, Kabuki syndrome, Cornelia De Lange syndrome, Rubinstein–Taybi syndrome), sharing an overlapping phenotype. On the other hand, KMT2A somatic mutations have been reported in several tumors, mainly blood malignancies. Due to its evolutionary conservation, the role of KMT2A in embryonic development, hematopoiesis and neurodevelopment has been explored in different animal models, and in recent decades, epigenetic treatments for disorders linked to KMT2A dysfunction have been extensively investigated. To note, pharmaceutical compounds acting on tumors characterized by KMT2A mutations have been formulated, and even nutritional interventions for chromatinopathies have become the object of study due to the role of microbiota in epigenetic regulation. Full article

ARID1B is one of the most frequently mutated genes in intellectual disability (~1%). Most variants are readily classified, since they are de novo and are predicted to lead to loss of function, and therefore classified as pathogenic according to the American College of Medical Genetics and Genomics (ACMG) guidelines for the interpretation of sequence variants. However, familial loss-of-function variants can also occur and can be challenging to interpret. Such variants may be pathogenic with variable expression, causing only a mild phenotype in a parent. Alternatively, since some regions of the ARID1B gene seem to be lacking pathogenic variants, loss-of-function variants in those regions may not lead to ARID1B haploinsufficiency and may therefore be benign. We describe 12 families with potential loss-of-function variants, which were either familial or with unknown inheritance and were in regions where pathogenic variants have not been described or are otherwise challenging to interpret. We performed detailed clinical and DNA methylation studies, which allowed us to confidently classify most variants. In five families we observed transmission of pathogenic variants, confirming their highly variable expression. Our findings provide further evidence for an alternative translational start site and we suggest updates for the ACMG guidelines for the interpretation of sequence variants to incorporate DNA methylation studies and facial analyses. Full article

Coffin-Siris syndrome (CSS, MIM 135900) is a multi-system intellectual disability syndrome characterized by classic dysmorphic features, developmental delays, and organ system anomalies. Genes in the BRG1(BRM)-associated factors (BAF, Brahma associated factor) complex have been shown to be causative, including ARID1A, ARID1B, ARID2, DPF2, SMARCA4, SMARCB1, SMARCC2, SMARCE1, SOX11, and SOX4. In order to describe more robust genotype-phenotype correlations, we collected data from 208 individuals from the CSS/BAF complex registry with pathogenic variants in seven of these genes. Data were organized into cohorts by affected gene, comparing genotype groups across a number of binary and quantitative phenotypes. We determined that, while numerous phenotypes are seen in individuals with variants in the BAF complex, hypotonia, hypertrichosis, sparse scalp hair, and hypoplasia of the distal phalanx are still some of the most common features. It has been previously proposed that individuals with ARID-related variants are thought to have more learning and developmental struggles, and individuals with SMARC-related variants, while they also have developmental delay, tend to have more severe organ-related complications. SOX-related variants also have developmental differences and organ-related complications but are most associated with neurodevelopmental differences. While these generalizations still overall hold true, we have found that all individuals with BAF-related conditions are at risk of many aspects of the phenotype, and management and surveillance should be broad. Full article

Neurogenesis is an elegantly coordinated developmental process that must maintain a careful balance of proliferation and differentiation programs to be compatible with life. Due to the fine-tuning required for these processes, epigenetic mechanisms (e.g., DNA methylation and histone modifications) are employed, in addition to changes in mRNA transcription, to regulate gene expression. The purpose of this review is to highlight what we currently know about histone 4 lysine 20 (H4K20) methylation and its role in the developing brain. Utilizing publicly-available RNA-Sequencing data and published literature, we highlight the versatility of H4K20 methyl modifications in mediating diverse cellular events from gene silencing/chromatin compaction to DNA double-stranded break repair. From large-scale human DNA sequencing studies, we further propose that the lysine methyltransferase gene, KMT5B (OMIM: 610881), may fit into a category of epigenetic modifier genes that are critical for typical neurodevelopment, such as EHMT1 and ARID1B, which are associated with Kleefstra syndrome (OMIM: 610253) and Coffin-Siris syndrome (OMIM: 135900), respectively. Based on our current knowledge of the H4K20 methyl modification, we discuss emerging themes and interesting questions on how this histone modification, and particularly KMT5B expression, might impact neurodevelopment along with current challenges and potential avenues for future research. Full article