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Numerical aberrations of permanent dentition and dystopic tooth eruption are part of the phenotype of the tumor predisposition syndrome neurofibromatosis type 1 (NF1). In these cases, surplus tooth germs usually develop in the alveolar processes of the jaw. This report attests to the dystopic development of a dysplastic supernumerary tooth in NF1 arising outside the jaw. The 8-year-old male patient developed a microdont outside the bone and above the occlusal plane of the retained maxillary right second molar. The supernumerary tooth was completely embedded in oral soft tissue. Hyperplastic oral soft tissue in the molar region and microdont were excised. Specimen of the mucosa surrounding the teeth was interspersed with diffuse and plexiform neurofibroma. The retained upper right first molar emerged spontaneously within a few months after surgery. The upper right second molar did not change position. Odontogenesis can take place within tumorous oral mucosa in NF1. Surgical removal of the tumorous mucous membrane facilitates tooth eruption in some cases.

Loss-of-function variants in ANKRD11 were identified as the cause of KBG syndrome, an autosomal dominant syndrome with specific dental, neurobehavioural, craniofacial and skeletal anomalies. We present the largest cohort of KBG syndrome cases confirmed by ANKRD11 variants reported so far, consisting of 20 patients from 13 families. Sixteen patients were molecularly diagnosed by Sanger sequencing of ANKRD11, one familial case and three sporadic patients were diagnosed through whole-exome sequencing and one patient was identified through genomewide array analysis. All patients were evaluated by a clinical geneticist. Detailed orofacial phenotyping, including orthodontic evaluation, intra-oral photographs and orthopantomograms, was performed in 10 patients and revealed besides the hallmark feature of macrodontia of central upper incisors, several additional dental anomalies as oligodontia, talon cusps and macrodontia of other teeth. Three-dimensional (3D) stereophotogrammetry was performed in 14 patients and 3D analysis of patients compared with controls showed consistent facial dysmorphisms comprising a bulbous nasal tip, upturned nose with a broad base and a round or triangular face. Many patients exhibited neurobehavioural problems, such as autism spectrum disorder or hyperactivity. One-third of patients presented with (conductive) hearing loss. Congenital heart defects, velopharyngeal insufficiency and hip anomalies were less frequent. On the basis of our observations, we recommend cardiac assessment in children and regular hearing tests in all individuals with a molecular diagnosis of KBG syndrome. As ANKRD11 is a relatively common gene in which sequence variants have been identified in individuals with neurodevelopmental disorders, it seems an important contributor to the aetiology of both sporadic and familial cases.

Background: Gardner syndrome is a rare genetic cancer predisposition disorder characterized by intestinal polyposis, multiple osteomas, and soft and hard tissue tumors. Dental anomalies are present in approximately 30%–70% of patients with Gardner syndrome and can be discovered during routine dental examinations. However, sometimes the diagnosis is challenging due to the high clinical variability and incomplete clinical picture. Herein, we report a family with various dental and bone anomalies, in which the definitive diagnosis was established with the help of a comprehensive genetic analysis based on state-of-the-art next-generation sequencing technology. Case presentation: A 17-year-old female index patient presented with dental (caries, impacted, retained and anteriorly located teeth) and atypical bone anomalies not resembling Gardner syndrome. She was first referred to our Genetic Counselling Unit at the age of 11 due to an atypical bone abnormality identified by a panoramic X-ray. Tooth 3.6 was surgically removed and the histopathology report revealed a Paget’s disease-like bone metabolic disorder with mixed osteoblastic and osteoclastic activity of the mandible. A small lumbar subcutaneous tumor was discovered by physical examination. Ultrasound examination of the tumor raised the possibility of a soft tissue propagation of chondromatosis. Her sister, 2 years younger at the age of 14, had some benign tumors (multiple exostoses, odontomas, epidermoid cysts) and impacted teeth. Their mother had also skeletal symptoms. Her lower teeth did not develop, the 9th-10th ribs were fused, and she complained of intermittent jaw pain. A cranial CT scan showed fibrous dysplasia on the cranial bones. Whole exome sequencing identified a heterozygous pathogenic nonsense mutation (c.4700C>G; p.Ser1567*) in the APC gene in the index patient’s DNA. Targeted sequencing revealed the same variant in the DNA of the other affected family members (the sister and the mother). Conclusion: Early diagnosis of this rare, genetically determined syndrome is very important, because of the potentially high malignant transformation of intestinal polyps. Dentists should be familiar with the typical maxillofacial features of this disorder, to be able to refer patients to genetic counseling. Dental anomalies often precede the intestinal polyposis and facilitate the early diagnosis, thereby increasing the patients’ chances of survival. Genetic analysis may be necessary in patients with atypical phenotypic signs.

Background To investigate how successfully the classification of patients with and without dental anomalies was achieved through four experiments involving different dental anomalies. Methods Lateral cephalometric radiographs (LCRs) from 526 individuals aged between 14 and 22 years were included. Four experiments involving different dental anomalies were created. Experiment 1 included the total dental anomaly group and control group (CG). Experiment 2 only had dental agenesis and a CG. Experiment 3 consisted of only palatally impacted canines and the CG. Experiment 4 comprised patients with various dental defects (transposition, hypodontia, agenesis-palatally affected canine, peg-shaped laterally, hyperdontia) and the CG. Twelve sella measurements and assessments of the ponticulus posticus and posterior arch deficiency were given as input. The target was to distinguish between anomalies and controls. The CatBoost algorithm was applied to classify patients with and without dental anomalies. Results In order from lowest to highest, the predictive accuracies of the experiments were as follows: experiment 4 < experiment 2 < experiment 3 < experiment 1. The sella area (SA) (mm2) was the most important variable in experiment 1. The most significant variable in prediction model of experiment 2 was sella height posterior (SHP) (mm). Sella area (SA) (mm2) was again the most relevant variable in experiment 3. The most important variable in experiment 4 was sella height median (SHM) (mm). Conclusions Every prediction model from the four experiments prioritized different variables. These findings may suggest that related research should focus on specific traits from a diagnostic perspective.

Ankyrin repeat domain containing-protein 11 (ANKRD11), a transcriptional factor predominantly localized in the cell nucleus, plays a crucial role in the expression regulation of key genes by recruiting chromatin remodelers and interacting with specific transcriptional repressors or activators during numerous biological processes. Its pathogenic variants are strongly linked to the pathogenesis and progression of multisystem disorder known as KBG syndrome. With the widespread application of high-throughput DNA sequencing technologies in clinical medicine, numerous pathogenic variants in the ANKRD11 gene have been reported. Patients with KBG syndrome usually exhibit a broad phenotypic spectrum with a variable degree of severity, even if having identical variants. In addition to distinctive dental, craniofacial and neurodevelopmental abnormalities, patients often present with skeletal anomalies, particularly postnatal short stature. The relationship between ANKRD11 variants and short stature is not well-understood, with limited knowledge regarding its occurrence rate or underlying biological mechanism involved. This review aims to provide an updated analysis of the molecular spectrum associated with ANKRD11 variants, investigate the prevalence of the short stature among patients harboring these variants, evaluate the efficacy of recombinant human growth hormone in treating children with short stature and ANKRD11 variants, and explore the biological mechanisms underlying short stature from both scientific and clinical perspectives. Our investigation indicated that frameshift and nonsense were the most frequent types in 583 pathogenic or likely pathogenic variants identified in the ANKRD11 gene. Among the 245 KBGS patients with height data, approximately 50% displayed short stature. Most patients showed a positive response to rhGH therapy, although the number of patients receiving treatment was limited. ANKRD11 deficiency potentially disrupts longitudinal bone growth by affecting the orderly differentiation of growth plate chondrocytes. Our review offers crucial insights into the association between ANKRD11 variants and short stature and provides valuable guidance for precise clinical diagnosis and treatment of patients with KBG syndrome.

Blepharocheilodontic syndrome (BCDS) consists of lagophthalmia, ectropion of the lower eyelids, distichiasis, euryblepharon, cleft lip/palate and dental anomalies and has autosomal dominant inheritance with variable expression. We identified heterozygous variants in two genes of the cadherin–catenin complex, CDH1, encoding E-cadherin, and CTNND1, encoding p120 catenin delta1 in 15 of 17 BCDS index patients, as was recently described in a different publication. CDH1 plays an essential role in epithelial cell adherence; CTNND1 binds to CDH1 and controls the stability of the complex. Functional experiments in zebrafish and human cells showed that the CDH1 variants impair the cell adhesion function of the cadherin–catenin complex in a dominant-negative manner. Variants in CDH1 have been linked to familial hereditary diffuse gastric cancer and invasive lobular breast cancer; however, no cases of gastric or breast cancer have been reported in our BCDS cases. Functional experiments reported here indicated the BCDS variants comprise a distinct class of CDH1 variants. Altogether, we identified the genetic cause of BCDS enabling DNA diagnostics and counseling, in addition we describe a novel class of dominant negative CDH1 variants.

Inversions are structural variants that are generally balanced. However, they could lead to gene disruptions or have positional effects leading to diseases. Mutations in the NHS gene cause Nance-Horan syndrome, an X-linked disorder characterised by congenital cataracts and dental anomalies. Here, we aimed to characterise a balanced pericentric inversion X(p22q27), maternally inherited, in a child with syndromic bilateral cataracts by breakpoint mapping using whole-genome sequencing (WGS). 30× Illumina paired-end WGS was performed in the proband, and breakpoints were confirmed by Sanger sequencing. EdU assays and FISH analysis were used to assess skewed X-inactivation patterns. RNA expression of involved genes in the breakpoint boundaries was evaluated by droplet-digital PCR. We defined the breakpoint position of the inversion at Xp22.13, with a 15 bp deletion, disrupting the unusually large intron 1 of the canonical NHS isoform, and also perturbing topologically-associated domains (TADs). Moreover, a microhomology region of 5 bp was found on both sides. RNA analysis confirmed null and reduced NHS expression in the proband and his unaffected mother, respectively. In conclusion, we report the first chromosomal inversion disrupting NHS, fine-mapped by WGS. Our data expand the clinical spectrum and the pathogenic mechanisms underlying the NHS defects.

Background: SATB2-associated syndrome (SAS), also known as Glass syndrome, is a neurodevelopmental disorder (NDD) characterized by intellectual disability, developmental delay, absent or limited speech, and distinctive craniofacial and dental anomalies. It is caused by autosomal dominant pathogenic variants in the SATB2 gene, which plays a crucial role in brain, dental, and jaw development. Due to its variable phenotype, clinical diagnosis can be challenging, necessitating genetic confirmation. Methods: We present six new cases of SAS with SATB2 germline variants identified through next generation sequencing (NGS) technologies, expanding the known genetic and clinical spectrum of the syndrome. Detailed clinical phenotyping was performed for all patients. Results: Our cohort exhibits a broad range of clinical manifestations consistent with SAS, encompassing severe intellectual disability, profound speech delay, various palatal and dental abnormalities. We report the oldest adult patient (56 years old) carrying an in-frame duplication, and a pediatric patient with a missense variant who presented a significant reduction in visual acuity, likely of neurological or cortical origin, in the absence of ophthalmological abnormalities. SATB2 variants include three missenses, two in-frame deletion/duplication and one frameshift variant, several of which are novel and classified as likely pathogenic or pathogenic according to ACMG guidelines. Conclusions: This report provides new clinical and genetic insights into the landscape of SAS. Our findings confirm the phenotypic heterogeneity of SAS and highlight the critical role of comprehensive genetic testing for accurate diagnosis in NDD patients.

Background: KBG syndrome is a multisystem developmental disorder characterized by macrodontia of the upper permanent incisors, distinctive facial features, a short stature, developmental delay, variable intellectual disability, and behavioral issues. Heterozygous chromosomal deletion encompassing the partial or entire ANKRD11 gene, as well as the loss of function mutations, result in haploinsufficiency of the gene, leading to KBG syndrome. This indicates that precise levels of ANKRD11 transcripts or protein are essential for human development. Clinical report: Here, we report three individuals who present with clinical features of KBG syndrome. These individuals carry microdeletions encompassing only the non-coding exon 1 of ANKRD11 and its upstream region. Our molecular analysis showed that this deletion leads to reduction in the ANKRD11 transcript and global transcriptome alterations similar to those seen in KBG syndrome patients. Conclusions: We concluded that microdeletions involving non-coding exon 1 of ANKRD11 lead to KBG syndrome. Our study suggests the utility of transcriptome analysis in aiding the interpretation of novel copy number variants in the non-coding genomic region of ANKRD11.

The composite structure of the mammalian skull, which forms predominantly via intramembranous ossification, requires precise pre- and post-natal growth regulation of individual calvarial elements. Disturbances of this process frequently cause severe clinical manifestations in humans. Enhanced DNA binding by a mutant MSX2 homeodomain results in a gain of function and produces craniosynostosis in humans 1 , 2 . Here we show that Msx2 -deficient mice have defects of skull ossification and persistent calvarial foramen. This phenotype results from defective proliferation of osteoprogenitors at the osteogenic front during calvarial morphogenesis, and closely resembles that associated with human MSX2 haploinsufficiency in parietal foramina 3 (PFM). Msx2 −/− mice also have defects in endochondral bone formation. In the axial and appendicular skeleton, post-natal deficits in Pth/Pthrp receptor (Pthr) signalling and in expression of marker genes for bone differentiation indicate that Msx2 is required for both chondrogenesis and osteogenesis. Consistent with phenotypes associated with PFM, Msx2 -mutant mice also display defective tooth, hair follicle and mammary gland development, and seizures, the latter accompanied by abnormal development of the cerebellum. Most Msx2 -mutant phenotypes, including calvarial defects, are enhanced by genetic combination with Msx1 loss of function, indicating that Msx gene dosage can modify expression of the PFM phenotype. Our results provide a developmental basis for PFM and demonstrate that Msx2 is essential at multiple sites during organogenesis.