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Clinical Genetics Mar 2024Amelogenesis imperfecta (AI) represents a group of clinically and genetically heterogeneous disorders that affect enamel formation and mineralization. Although AI is...
Amelogenesis imperfecta (AI) represents a group of clinically and genetically heterogeneous disorders that affect enamel formation and mineralization. Although AI is commonly considered a monogenic disorder, digenic inheritance is rarely reported. In this study, we recruited two nonconsanguineous Chinese families exhibiting diverse phenotypes of enamel defects among affected family members. Digenic variants were discovered in both probands. In family 1, the proband inherited a paternal frameshift variant in LAMA3 (NM_198129.4:c.3712dup) and a maternal deletion encompassing the entire AMELX gene. This resulted in a combined hypoplastic and hypomineralized AI phenotype, which was distinct from the parents' manifestations. In family 2, whole-exome sequencing analysis revealed the proband carried a maternal heterozygous splicing variant in COL17A1 (NC_000010.11 (NM_000494.3): c.4156 + 2dup) and compound heterozygous variants in RELT (paternal: NM_032871.4:c.260A > T; maternal: NM_032871.4:c.521 T > G). These genetic changes caused the abundant irregular enamel defects observed in the proband, whereas other affected family members carrying heterozygous variants in both COL17A1 and RELT displayed only horizontal grooves as their phenotype. The pathogenicity of the novel COL17A1 splice site variant was confirmed through RT-PCR and minigene assay. This study enhances our understanding by highlighting the potential association between the co-occurrence of variants in two genes and variable phenotypes observed in AI patients.
Topics: Humans; Amelogenesis Imperfecta; Phenotype; Frameshift Mutation; Extracellular Matrix Proteins; Biological Variation, Population; Pedigree
PubMed: 37937686
DOI: 10.1111/cge.14449 -
Archives of Oral Biology Aug 2024To identify the genetic cause of a Chinese family with hypomaturation amelogenesis imperfecta (AI) and to characterize the structure of GPR68 mutated enamel in order to...
OBJECTIVES
To identify the genetic cause of a Chinese family with hypomaturation amelogenesis imperfecta (AI) and to characterize the structure of GPR68 mutated enamel in order to develop a deeper understanding of the role of the GPR68 protein during the intricate process of amelogenesis.
DESIGN
One Chinese family with generalized hypomaturation AI was recruited. Two of the third molars from the proband were subjected to scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX). Whole exome sequencing (WES) was performed, and the identified mutation was confirmed by Sanger sequencing. Bioinformatics studies were further conducted to analyze the potential deleterious effects of the mutation.
RESULTS
The proband presented with a hypomaturation AI phenotype, characterized by fragile and discolored enamel surface. The AI enamel showed prismatic structure, which was sporadically obscured by areas of amorphous material and porous structure. EDX analysis showed the proband's enamel demonstrated a significant decrease in calcium and phosphorus content and a significant increase in oxygen compared with normal enamel. A novel homozygous mutation of G protein-coupled receptor 68 (GPR68) (c .149 T > A, p.Ile50Asn) was identified in the proband. Bioinformatics analysis indicated that the mutation site displayed a high level of evolutionary conservation among species, and the mutation might impact the stability and conformation of the protein.
CONCLUSION
The novel homozygous GPR68 mutation resulted in hypomaturation AI. We first described the effect of GPR68 mutation on enamel structure. Our results provide new genetic evidence that mutations involved in GPR68 contribute to hypomaturation AI.
Topics: Female; Humans; Male; Amelogenesis Imperfecta; China; Computational Biology; Dental Enamel; Exome Sequencing; Microscopy, Electron, Scanning; Mutation; Pedigree; Phenotype; Receptors, G-Protein-Coupled; Spectrometry, X-Ray Emission
PubMed: 38761453
DOI: 10.1016/j.archoralbio.2024.105991 -
Scientific Reports Jan 2024Kohlschütter-Tönz syndrome (KTS) is a rare autosomal recessive disorder characterized by severe intellectual disability, early-onset epileptic seizures, and...
Kohlschütter-Tönz syndrome (KTS) is a rare autosomal recessive disorder characterized by severe intellectual disability, early-onset epileptic seizures, and amelogenesis imperfecta. Here, we present a novel Rogdi mutant mouse deleting exons 6-11- a mutation found in KTS patients disabling ROGDI function. This Rogdi mutant model recapitulates most KTS symptoms. Mutants displayed pentylenetetrazol-induced seizures, confirming epilepsy susceptibility. Spontaneous locomotion and circadian activity tests demonstrate Rogdi mutant hyperactivity mirroring patient spasticity. Object recognition impairment indicates memory deficits. Rogdi mutant enamel was markedly less mature. Scanning electron microscopy confirmed its hypomineralized/hypomature crystallization, as well as its low mineral content. Transcriptomic RNA sequencing of postnatal day 5 lower incisors showed downregulated enamel matrix proteins Enam, Amelx, and Ambn. Enamel crystallization appears highly pH-dependent, cycling between an acidic and neutral pH during enamel maturation. Rogdi teeth exhibit no signs of cyclic dental acidification. Additionally, expression changes in Wdr72, Slc9a3r2, and Atp6v0c were identified as potential contributors to these tooth acidification abnormalities. These proteins interact through the acidifying V-ATPase complex. Here, we present the Rogdi mutant as a novel model to partially decipher KTS pathophysiology. Rogdi mutant defects in acidification might explain the unusual combination of enamel and rare neurological disease symptoms.
Topics: Humans; Animals; Mice; Amelogenesis Imperfecta; Epilepsy; Dementia; Seizures; Mutation; Tooth Abnormalities; Membrane Proteins; Nuclear Proteins
PubMed: 38172607
DOI: 10.1038/s41598-023-50870-2 -
BMC Medical Genomics Nov 2023This study reported the first case of Kohlschütter-Tönz syndrome (KTS) in China and reviewed the literature of the reported cases. (Review)
Review
PURPOSE
This study reported the first case of Kohlschütter-Tönz syndrome (KTS) in China and reviewed the literature of the reported cases.
METHODS
This patient was registered at the Children's Hospital of Chongqing Medical University. The patient's symptoms and treatments were recorded in detail, and the patient was monitored for six years. We employed a combination of the following search terms and Boolean operators in our search strategy: Kohlschütter-Tönz syndrome, KTS, and ROGDI. These terms were carefully selected to capture a broad range of relevant publications in PubMed, Web of Science, WHO Global Health Library, and China National Knowledge Infrastructure, including synonyms, variations, and specific terms related to KTS. The pathogenicity of the variants was predicted using SpliceAI and MutationTaster, and the structures of the ROGDI mutations were constructed using I-TASSER.
RESULTS
This is the first case report of KTS in China. Our patient presented with epilepsy, global developmental delay, and amelogenesis imperfecta. A trio-WES revealed homozygous mutations in ROGDI (c.46-37_46-30del). The brain magnetic resonance imaging (MRI) and video electroencephalogram (VEEG) were normal. The efficacy of perampanel (PMP) in treating seizures and intellectual disability was apparent. Furthermore, 43 cases of ROGDI-related KTS were retrieved. 100% exhibited epilepsy, global developmental delay, and amelogenesis imperfecta. 17.2% received a diagnosis of attention deficit hyperactivity disorder (ADHD), and 3.4% were under suspicion of autism spectrum disorder (ASD). Language disorders were observed in all patients. Emotional disorders, notably self-harm behaviors (9.1%), were also reported.
CONCLUSION
ROGDI-related KTS is a rare neurodegenerative disorder, characterized by three classic clinical manifestations: epilepsy, global developmental delay, and amelogenesis imperfecta. Moreover, patients could present comorbidities, including ADHD, ASD, emotional disorders, and language disorders. PMP may be a potential drug with relatively good efficacy, but long-term clinical trials are still needed.
Topics: Child; Humans; Amelogenesis Imperfecta; Autism Spectrum Disorder; Epilepsy; Language Disorders; Membrane Proteins; Nuclear Proteins
PubMed: 37974187
DOI: 10.1186/s12920-023-01728-z -
Clinical Oral Investigations Oct 2023The current research on single-nucleotide polymorphism (SNP) mutation sites at different positions of the FAM83H gene and their phenotypic changes leading to...
OBJECTIVES
The current research on single-nucleotide polymorphism (SNP) mutation sites at different positions of the FAM83H gene and their phenotypic changes leading to amelogenesis imperfecta (AI) is inconsistent. We identified a previously reported heterozygous nonsense mutation c.1192C>T (p.Q398*) in the FAM83H gene and conducted a comprehensive analysis of the dental ultrastructure and chemical composition changes induced by this mutation. Additionally, we predicted the protein feature affected by this mutation site. The aim was to further deepen our understanding of the diversity of AI caused by different mutation sites in the FAM83H gene.
METHODS
Whole-exome sequencing (WES) and Sanger sequencing were used to confirm the mutation sites. Physical features of the patient's teeth were investigated using various methods including cone beam computer tomography (CBCT), scanning electron microscopy (SEM), contact profilometry (roughness measurement), and a nanomechanical tester (nanoindentation measurement). The protein features of wild-type and mutant FAM83H were predicted using bioinformatics methods.
RESULTS
One previously discovered FAM83H heterozygous nonsense mutation c.1192C>T (p.Q398*) was detected in the patient. SEM revealed inconsistent dentinal tubules, and EDS showed that calcium and phosphorus were lower in the patient's dentin but higher in the enamel compared to the control tooth. Roughness measurements showed that AI patients' teeth had rougher occlusal surfaces than those of the control tooth. Nanoindentation measurements showed that the enamel and dentin hardness values of the AI patients' teeth were both significantly reduced compared to those of the control tooth. Compared to the wild-type FAM83H protein, the mutant FAM83H protein shows alterations in stability, hydrophobicity, secondary structure, and tertiary structure. These changes could underlie functional differences and AI phenotype variations caused by this mutation site.
CONCLUSIONS
This study expands the understanding of the effects of FAM83H mutations on tooth structure.
CLINICAL RELEVANCE
Our study enhances our understanding of the genetic basis of AI and may contribute to improved diagnostics and personalized treatment strategies for patients with FAM83H-related AI.
Topics: Humans; Amelogenesis Imperfecta; Codon, Nonsense; Dental Enamel; Proteins; Mutation
PubMed: 37615776
DOI: 10.1007/s00784-023-05228-3 -
Special Care in Dentistry : Official... Dec 2023Jalili syndrome (JS) (MIM#217080) is a rare autosomal recessive disorder with oculo-dental malformations. The clinical phenotype is characterized by the presence of...
Jalili syndrome (JS) (MIM#217080) is a rare autosomal recessive disorder with oculo-dental malformations. The clinical phenotype is characterized by the presence of Cone-Rod Dystrophy (CRD) and Amelogenesis Imperfecta (AI). Genetic mechanism entails a mutation in the CNNM4, a metal transporter gene located on Chromosome 2q11.2. A high fluoride concentration in groundwater has also been identified as an epigenetic factor in this syndrome. JS draws the attention of dentists due to its distinct oral manifestations. To the best of our knowledge, this is the first genetically confirmed pediatric case report from the Indian subcontinent emphasizing the clinical and radiographic features of this condition and its management in a 6-year-old child.
PubMed: 38151709
DOI: 10.1111/scd.12953 -
Experimental & Molecular Medicine Jul 2024The asymmetric division of stem cells permits the maintenance of the cell population and differentiation for harmonious progress. Developing mouse incisors allows...
The asymmetric division of stem cells permits the maintenance of the cell population and differentiation for harmonious progress. Developing mouse incisors allows inspection of the role of the stem cell niche to provide specific insights into essential developmental phases. Microtubule-associated serine/threonine kinase family member 4 (Mast4) knockout (KO) mice showed abnormal incisor development with low hardness, as the size of the apical bud was decreased and preameloblasts were shifted to the apical side, resulting in amelogenesis imperfecta. In addition, Mast4 KO incisors showed abnormal enamel maturation, and stem cell maintenance was inhibited as amelogenesis was accelerated with Wnt signal downregulation. Distal-Less Homeobox 3 (DLX3), a critical factor in tooth amelogenesis, is considered to be responsible for the development of amelogenesis imperfecta in humans. MAST4 directly binds to DLX3 and induces phosphorylation at three residues within the nuclear localization site (NLS) that promotes the nuclear translocation of DLX3. MAST4-mediated phosphorylation of DLX3 ultimately controls the transcription of DLX3 target genes, which are carbonic anhydrase and ion transporter genes involved in the pH regulation process during ameloblast maturation. Taken together, our data reveal a novel role for MAST4 as a critical regulator of the entire amelogenesis process through its control of Wnt signaling and DLX3 transcriptional activity.
PubMed: 38945953
DOI: 10.1038/s12276-024-01264-5 -
Journal of Dentistry For Children... Jan 2024Enamel renal gingival syndrome is a rare clinical condition characterized by the presence of amelogenesis imperfecta hypoplastic type, gingival fibromatosis and delayed...
Enamel renal gingival syndrome is a rare clinical condition characterized by the presence of amelogenesis imperfecta hypoplastic type, gingival fibromatosis and delayed tooth eruption, in addition to nephrocalcinosis with normal blood calcium levels. It is inherited as an autosomal recessive trait caused by mutations in the FAM20A gene located on chromosome 17q24.2. The purpose of this report is to describe a case of enamel renal gingival syndrome and discuss its distinct features and management.
Topics: Humans; Male; Amelogenesis Imperfecta; Dental Enamel Proteins; Fibromatosis, Gingival; Nephrocalcinosis; Child
PubMed: 38671566
DOI: No ID Found -
Swiss Dental Journal Feb 2024The aim of the treatment of this case was to restore the form, function and aesthetics of all teeth in a patient with amelogenesis imperfecta within the age limit of the...
The aim of the treatment of this case was to restore the form, function and aesthetics of all teeth in a patient with amelogenesis imperfecta within the age limit of the disability insurance (IV). Single-tooth zirconia crowns were selected as the treatment of choice and cemented with a conventional glass ionomer cement. For the maintenance of the oral rehabilitation and the protection of the reconstructions a michigan splint was produced and instructed to be carried over night.
Topics: Humans; Amelogenesis Imperfecta; Crowns; Glass Ionomer Cements; Zirconium; Female; Male; Esthetics, Dental; Dental Prosthesis Design; Occlusal Splints
PubMed: 38739045
DOI: 10.61872/sdj-2024-03-02 -
Heliyon Jan 2024Brachyolmia is a heterogeneous group of developmental disorders characterized by a short trunk, short stature, scoliosis, and generalized platyspondyly without...
Brachyolmia is a heterogeneous group of developmental disorders characterized by a short trunk, short stature, scoliosis, and generalized platyspondyly without significant deformities in the long bones. DASS (Dental Abnormalities and Short Stature), caused by alterations in the gene, was previously considered as a subtype of brachyolmia. The present study investigated three unrelated consanguineous families (A, B, C) with Brachyolmia and DASS from Egypt and Pakistan. In our Egyptian patients, we also observed hearing impairment. Exome sequencing was performed to determine the genetic causes of the diverse clinical conditions in the patients. Exome sequencing identified a novel homozygous splice acceptor site variant (:c.3629-1G > T; p. ?) responsible for DASS phenotypes and a known homozygous missense variant (: c.590T > C; p.Ile197Thr) causing hearing impairment in the Egyptian patients. In addition, two previously reported homozygous frameshift variants (:c.132delG; p.Pro45Argfs*25) and (:c.2216delG; p.Gly739Alafs*7) were identified in Pakistani patients. This study emphasizes the vital role of in the axial skeleton and tooth morphogenesis and expands the mutational spectrum of . We are reporting variants in seven patients of three families, majorly causing brachyolmia with dental and cardiac anomalies. Skeletal assessment documented short webbed neck, broad chest, evidences of mild long bones involvement, short distal phalanges, pes planus and osteopenic bone texture as additional associated findings expanding the clinical phenotype of DASS. The current study reveals that the hearing impairment phenotype in Egyptian patients of family A has a separate transmission mechanism independent of .
PubMed: 38192829
DOI: 10.1016/j.heliyon.2023.e23688