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Journal of Personalized Medicine Feb 2023Amelogenesis imperfecta (AI) is a heterogeneous collection of hereditary enamel defects. The affected enamel can be classified as hypoplastic, hypomaturation, or...
Amelogenesis imperfecta (AI) is a heterogeneous collection of hereditary enamel defects. The affected enamel can be classified as hypoplastic, hypomaturation, or hypocalcified in form. A better understanding of normal amelogenesis and improvements in our ability to diagnose AI through genetic testing can be realized through more complete knowledge of the genes and disease-causing variants that cause AI. In this study, mutational analysis was performed with whole exome sequencing (WES) to identify genetic etiology underlying the hypomaturation AI condition in affected families. Mutational analyses identified biallelic mutations in four hypomaturation AI families. Novel mutations include a homozygous deletion and insertion mutation (NM_182758.4: c.2680_2699delinsACTATAGTT, p.(Ser894Thrfs*15)), compound heterozygous mutations (paternal c.2332dupA, p.(Met778Asnfs*4)) and (maternal c.1287_1289del, p.(Ile430del)) and a homozygous 3694 bp deletion that includes exon 14 (NG_017034.2:g.96472_100165del). A homozygous recurrent mutation variant (c.1467_1468delAT, p.(Val491Aspfs*8)) was also identified. Current ideas on WDR72 structure and function are discussed. These cases expand the mutational spectrum of mutations causing hypomaturation AI and improve the possibility of genetic testing to accurately diagnose AI caused by defects.
PubMed: 36836560
DOI: 10.3390/jpm13020326 -
Frontiers in Physiology 2020Stromal interaction molecule 1 () is one of the main components of the store operated Ca entry (SOCE) signaling pathway. Individuals with mutated present severely...
BACKGROUND
Stromal interaction molecule 1 () is one of the main components of the store operated Ca entry (SOCE) signaling pathway. Individuals with mutated present severely hypomineralized enamel characterized as amelogenesis imperfecta (AI) but the downstream molecular mechanisms involved remain unclear. Circadian clock signaling plays a key role in regulating the enamel thickness and mineralization, but the effects of -mediated AI on circadian clock are unknown.
OBJECTIVES
The aim of this study is to examine the potential links between SOCE and the circadian clock during amelogenesis.
METHODS
We have generated mice with ameloblast-specific deletion of ( /Amelx-iCre, cKO) and analyzed circadian gene expression profile in compared to control ( /Amelx-iCre) using ameloblast micro-dissection and RNA micro-array of 84 circadian genes. Expression level changes were validated by qRT-PCR and immunohistochemistry.
RESULTS
deletion has resulted in significant upregulation of the core circadian activator gene Brain and Muscle Aryl Hydrocarbon Receptor Nuclear Translocation 1 () and downregulation of the circadian inhibitor Period 2 (). Our analyses also revealed that SOCE disruption results in dysregulation of two additional circadian regulators; p38α mitogen-activated protein kinase (MAPK14) and transforming growth factor-beta1 (TGF-β1). Both MAPK14 and TGF-β1 pathways are known to play major roles in enamel secretion and their dysregulation has been previously implicated in the development of AI phenotype.
CONCLUSION
These data indicate that disruption of SOCE significantly affects the ameloblasts molecular circadian clock, suggesting that alteration of the circadian clock may be partly involved in the development of -mediated AI.
PubMed: 32848861
DOI: 10.3389/fphys.2020.00920 -
Frontiers in Physiology 2017During the secretory phase of their life-cycle, ameloblasts are highly specialized secretory cells whose role is to elaborate an extracellular matrix that ultimately... (Review)
Review
During the secretory phase of their life-cycle, ameloblasts are highly specialized secretory cells whose role is to elaborate an extracellular matrix that ultimately confers both form and function to dental enamel, the most highly mineralized of all mammalian tissues. In common with many other "professional" secretory cells, ameloblasts employ the unfolded protein response (UPR) to help them cope with the large secretory cargo of extracellular matrix proteins transiting their ER (endoplasmic reticulum)/Golgi complex and so minimize ER stress. However, the UPR is a double-edged sword, and, in cases where ER stress is severe and prolonged, the UPR switches from pro-survival to pro-apoptotic mode. The purpose of this review is to consider the role of the ameloblast UPR in the biology and pathology of amelogenesis; specifically in respect of amelogenesis imperfecta (AI) and fluorosis. Some forms of AI appear to correspond to classic proteopathies, where pathological intra-cellular accumulations of protein tip the UPR toward apoptosis. Fluorosis also involves the UPR and, while not of itself a classic proteopathic disease, shares some common elements through the involvement of the UPR. The possibility of therapeutic intervention by pharmacological modulation of the UPR in AI and fluorosis is also discussed.
PubMed: 28951722
DOI: 10.3389/fphys.2017.00653 -
Frontiers in Genetics 2022Amelogenesis imperfecta is a congenital disorder within a heterogeneous group of conditions characterized by enamel hypoplasia. Patients suffer from early tooth loss,...
Amelogenesis imperfecta is a congenital disorder within a heterogeneous group of conditions characterized by enamel hypoplasia. Patients suffer from early tooth loss, social embarrassment, eating difficulties, and pain due to an abnormally thin, soft, fragile, and discolored enamel with poor aesthetics and functionality. The etiology of amelogenesis imperfecta is complicated by genetic interactions. To identify mouse amelogenesis imperfecta-related genes (mAIGenes) and their respective phenotypes, we conducted a systematic literature review and database search and found and curated 70 mAIGenes across all of the databases. Our pathway enrichment analysis indicated that these genes were enriched in tooth development-associated pathways, forming four distinct groups. To explore how these genes are regulated and affect the phenotype, we predicted microRNA (miRNA)-gene interaction pairs using our bioinformatics pipeline. Our miRNA regulatory network analysis pinpointed that miR-16-5p, miR-27b-3p, and miR-23a/b-3p were hub miRNAs. The function of these hub miRNAs was evaluated through ameloblast differentiation assays with/without the candidate miRNA mimics using cultured mouse ameloblast cells. Our results revealed that overexpression of miR-16-5p and miR-27b-3p, but not miR-23a/b-3p, significantly inhibited ameloblast differentiation through regulation of mAIGenes. Thus, our study shows that miR-16-5p and miR-27b-3p are candidate pathogenic miRNAs for amelogenesis imperfecta.
PubMed: 35401675
DOI: 10.3389/fgene.2022.788259 -
Indian Journal of Nephrology 2017Bartter's syndrome is an autosomal recessive renal tubular disorder characterized by hypokalemia, hypochloremia, metabolic alkalosis, and hyperreninemia with normal...
Bartter's syndrome is an autosomal recessive renal tubular disorder characterized by hypokalemia, hypochloremia, metabolic alkalosis, and hyperreninemia with normal blood pressure. Bartter's syndrome is associated with hypercalciuria and nephrocalcinosis. Amelogenesis imperfecta (AI) is a group of hereditary disorders that affect dental enamel. AI could be part of several syndromes. The enamel renal syndrome is the association of AI and nephrocalcinosis. We report two patients of AI with Bartter's syndrome.
PubMed: 28904439
DOI: 10.4103/ijn.IJN_203_16 -
Journal of Dental Research Jan 2024Amelogenesis imperfecta (AI) comprises a group of rare, inherited disorders with abnormal enamel formation. Ameloblastin (AMBN), the second most abundant enamel matrix...
Amelogenesis imperfecta (AI) comprises a group of rare, inherited disorders with abnormal enamel formation. Ameloblastin (AMBN), the second most abundant enamel matrix protein (EMP), plays a critical role in amelogenesis. Pathogenic biallelic loss-of-function variants are known to cause recessive hypoplastic AI. A report of a family with dominant hypoplastic AI attributed to AMBN missense change p.Pro357Ser, together with data from animal models, suggests that the consequences of variants in human AI remain incompletely characterized. Here we describe 5 new pathogenic variants in 11 individuals with AI. These fall within 3 groups by phenotype. Group 1, consisting of 6 families biallelic for combinations of 4 different variants, have yellow hypoplastic AI with poor-quality enamel, consistent with previous reports. Group 2, with 2 families, appears monoallelic for a variant shared with group 1 and has hypomaturation AI of near-normal enamel volume with pitting. Group 3 includes 3 families, all monoallelic for a fifth variant, which are affected by white hypoplastic AI with a thin intact enamel layer. Three variants, c.209C>G; p.(Ser70*) (groups 1 and 2), c.295T>C; p.(Tyr99His) (group 1), and c.76G>A; p.(Ala26Thr) (group 3) were identified in multiple families. Long-read locus sequencing revealed these variants are on the same conserved haplotype, implying they originate from a common ancestor. Data presented therefore provide further support for possible dominant as well as recessive inheritance for -related AI and for multiple contrasting phenotypes. In conclusion, our findings suggest pathogenic variants have a more complex impact on human AI than previously reported.
Topics: Animals; Humans; Amelogenesis; Amelogenesis Imperfecta; Dental Enamel Proteins; Pedigree; Phenotype
PubMed: 38058155
DOI: 10.1177/00220345231203694 -
American Journal of Medical Genetics.... Dec 2006The amelogenesis imperfectas (AIs) are a clinically and genetically diverse group of conditions that are caused by mutations in a variety of genes that are critical for... (Review)
Review
The amelogenesis imperfectas (AIs) are a clinically and genetically diverse group of conditions that are caused by mutations in a variety of genes that are critical for normal enamel formation. To date, mutations have been identified in four genes (AMELX, ENAM, KLK4, MMP20) known to be involved in enamel formation. Additional yet to be identified genes also are implicated in the etiology of AI based on linkage studies. The diverse and often unique phenotypes resulting from the different allelic and non-allelic mutations in these genes provide an opportunity to better understand the role of these genes and their related proteins in enamel formation. Understanding the AI phenotypes also provides an aid to clinicians in directing molecular studies aimed at delineating the genetic basis underlying these diverse clinical conditions. Our current knowledge of the known mutations and associated phenotypes of the different AI subtypes are reviewed.
Topics: Amelogenesis Imperfecta; Genes, Dominant; Genes, Recessive; Genetic Diseases, X-Linked; Genetic Variation; Genotype; Humans; Kallikreins; Matrix Metalloproteinase 20; Mutation; Phenotype; Protein Sorting Signals
PubMed: 16838342
DOI: 10.1002/ajmg.a.31358 -
Journal of Personalized Medicine Oct 2023Hereditary conditions that affect tooth enamel in quantity and/or quality are called amelogenesis imperfecta (AI). AI can occur as an isolated condition or as a symptom...
Hereditary conditions that affect tooth enamel in quantity and/or quality are called amelogenesis imperfecta (AI). AI can occur as an isolated condition or as a symptom of a syndrome. An OMIM search with the term "AI" yielded 79 result entries. Mutations in the same gene cause syndromic or non-syndromic AI, depending on the nature of the mutations. In this study, we recruited two AI families and performed mutational analysis using whole-exome sequencing. The proband of family 1, with hypoplastic pitted AI and mild localized atopic dermatitis, had compound heterozygous mutations (paternal NM_000494.4: c.3598G>T, p.Asp1200Tyr and maternal c.1700G>A, p.Gly567Glu). The proband of family 2, with hypoplastic pitted AI and Jervell and Lange-Nielsen syndrome, had a recurrent mutation (NM_000228.3: c.3463_3475del, p.(Glu1155Thrfs*51)) in addition to compound heterozygous mutations in the KCNQ1 gene.
PubMed: 37888105
DOI: 10.3390/jpm13101494 -
Molecular Genetics & Genomic Medicine Oct 2019ENAM mutations cause autosomal dominant or recessive amelogenesis imperfecta (AI) and show a dose effect: enamel malformations are more severe or only penetrant when...
BACKGROUND
ENAM mutations cause autosomal dominant or recessive amelogenesis imperfecta (AI) and show a dose effect: enamel malformations are more severe or only penetrant when both ENAM alleles are defective.
METHODS
Whole exome sequences of recruited AI probands were initially screened for mutations in known AI candidate genes. Sanger sequencing was used to confirm sequence variations and their segregation with the disease phenotype. The co-occurrence of ENAM and LAMA3 mutations in one family raised the possibility of digenic inheritance. Enamel formed in Enam Ambn , Enam , Ambn , and Enam Ambn mice was characterized by dissection and backscattered scanning electron microscopy (bSEM).
RESULTS
ENAM mutations segregating with AI in five families were identified. Two novel ENAM frameshift mutations were identified. A single-nucleotide duplication (c.395dupA/p.Pro133Alafs*13) replaced amino acids 133-1142 with a 12 amino acid (ATTKAAFEAAIT*) sequence, and a single-nucleotide deletion (c.2763delT/p.Asp921Glufs*32) replaced amino acids 921-1142 with 31 amino acids (ESSPQQASYQAKETAQRRGKAKTLLEMMCPR*). Three families were heterozygous for a previously reported single-nucleotide ENAM deletion (c.588+1delG/p.Asn197Ilefs*81). One of these families also harbored a heterozygous LAMA3 mutation (c.1559G>A/p.Cys520Tyr) that cosegregated with both the AI phenotype and the ENAM mutation. In mice, Ambn maxillary incisors were normal. Ambn molars were also normal, except for minor surface roughness. Ambn mandibular incisors were sometimes chalky and showed minor chipping. Enam incisor enamel was thinner than normal with ectopic mineral deposited laterally. Enam molars were sometimes chalky and rough surfaced. Enam Ambn enamel was thin and rough, in part due to ectopic mineralization, but also underwent accelerated attrition.
CONCLUSION
Novel ENAM mutations causing AI were identified, raising to 22 the number of ENAM variations known to cause AI. The severity of the enamel phenotype in Enam Ambn double heterozygous mice is caused by composite digenic effects. Digenic inheritance should be explored as a cause of AI in humans.
Topics: Amelogenesis Imperfecta; Extracellular Matrix Proteins; Female; Frameshift Mutation; Gene Deletion; Heterozygote; Humans; Laminin; Male; Pedigree; Phenotype; Polymorphism, Single Nucleotide; Exome Sequencing
PubMed: 31478359
DOI: 10.1002/mgg3.928 -
Advances in Clinical and Experimental... Dec 2022Taurodontism is a morphological anomaly involving multirooted teeth that is characterized by a vertical shift of the pulp chamber and shortening of the roots. The... (Review)
Review
Taurodontism is a morphological anomaly involving multirooted teeth that is characterized by a vertical shift of the pulp chamber and shortening of the roots. The literature was analyzed to determine the impact of a diagnosis of taurodontism on dental treatment. A total of 85 full-text publications from the years 2005-2021 were analyzed and 20 publications were included in this research. The endodontic treatment of a taurodont tooth is challenging due to the apical displacement of the pulpal chamber floor and the incorrect configuration of the root canal system, or the presence of additional canals. In terms of prosthetics, the use of taurodont teeth as abutments is not recommended as they lack stability due to shorter roots. The extraction of taurodont teeth can be complicated due to an apical shift of the root furcation. In periodontology, taurodont teeth can have a better prognosis as there is less chance of furcation involvement. From an orthodontic point of view, it is important to note that taurodont teeth are not sufficiently embedded in the alveolus and have a greater tendency for root resorption. With regard to genetic diseases, it has been reported that this anomaly can exist as an isolated feature. However, the majority of authors agree that taurodontism is associated with conditions such as Down syndrome, Klinefelter syndrome, cleft lip and palate, hypodontia, amelogenesis imperfecta, and others. From a clinical standpoint, it is very important to diagnose taurodontism before treatment. A diagnosis of taurodontism can be important in the early diagnosis of malformations that commonly occur with this condition.
Topics: Humans; Dental Pulp Cavity; Cleft Lip; Cleft Palate; Tooth Abnormalities
PubMed: 36000881
DOI: 10.17219/acem/152120