Rare phenotype: Hand preaxial polydactyly associated with LRP6-related tooth agenesis in humans
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ABSTRACT:
SUBMITTER: Zhang L
PROVIDER: S-EPMC8581002 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:IntroductionGDF5-BMPR1B signaling pathway-associated chondrodysplasias are a genetically heterogeneous group of conditions with significant phenotypic and genotypic overlap, consisting of Hunter-Thompson-type acromesomelic dysplasia, Grebe dysplasia, and Du Pan syndrome. Constituting a spectrum of clinical severity, these disorders are characterized by disproportionate short stature mainly involving middle and distal segments of the extremities. Du Pan syndrome represents the mildest end of this spectrum with less marked shortened limbs, fibular agenesis or hypoplasia, absence of frequent joint dislocations, and carpotarsal fusions with deformed phalangeal bones.Case presentationHere, we report the first prenatal diagnosis of Du Pan syndrome based on the sonographic findings of bilateral fibular agenesis and ball-shaped toes mimicking preaxial polydactyly accompanying subtle brachydactyly in the family. GDF5 (NM_000557.5) sequencing identified a homozygous pathogenic variant c.1322T>C, p.(Leu441Pro) in the fetus and confirmed the carrier status in the mother.DiscussionWe suggest that the presence of bilateral fibular agenesis and the apparent image of preaxial polydactyly of the feet on prenatal ultrasound should alert suspicion to Du Pan syndrome, with the latter possibly being a sonographic pitfall. Alongside the fetal imaging, a detailed clinical examination of the expectant parents is also of great importance in establishing a preliminary diagnosis of Du Pan syndrome, as well as the other GDF5-BMPR1B-associated chondrodysplasias.
| S-EPMC10091002 | biostudies-literature
Project description:Familial tooth agenesis (FTA), distinguished by developmental failure of selected teeth, is one of the most prevalent craniofacial anomalies in humans. Mutations in genes involved in WNT/β-catenin signaling, including AXIN2 WNT10A, WNT10B, LRP6, and KREMEN1, are known to cause FTA. However, mutational interactions among these genes have not been fully explored. In this study, we characterized four FTA kindreds with LRP6 pathogenic mutations: p.(Gln1252*), p.(Met168Arg), p.(Ala754Pro), and p.(Asn1075Ser). The three missense mutations were predicted to cause structural destabilization of the LRP6 protein. Two probands carrying both an LRP6 mutant allele and a WNT10A variant exhibited more severe phenotypes, suggesting mutational synergism or digenic inheritance. Biallelic LRP6 mutations in a patient with many missing teeth further supported the dose-dependence of LRP6-associated FTA. Analysis of 21 FTA cases with 15 different LRP6 loss-of-function mutations revealed high heterogeneity of disease severity and a distinctive pattern of missing teeth, with maxillary canines being frequently affected. We hypothesized that various combinations of sequence variants in WNT-related genes can modulate WNT signaling activities during tooth development and cause a wide spectrum of tooth agenesis severity, which highlights the importance of exome/genome analysis for the genetic diagnosis of FTA in this era of precision medicine.
| S-EPMC8621929 | biostudies-literature
Project description:We aimed to identify a novel genetic cause of tooth agenesis (TA) and/or orofacial clefting (OFC) by combining whole-exome sequencing (WES) and targeted resequencing in a large cohort of TA and OFC patients.WES was performed in two unrelated patients: one with severe TA and OFC and another with severe TA only. After deleterious mutations were identified in a gene encoding low-density lipoprotein receptor-related protein 6 (LRP6), all its exons were resequenced with molecular inversion probes in 67 patients with TA, 1,072 patients with OFC, and 706 controls.We identified a frameshift (c.4594delG, p.Cys1532fs) and a canonical splice-site mutation (c.3398-2A>C, p.?) in LRP6, respectively, in the patient with TA and OFC and in the patient with severe TA only. The targeted resequencing showed significant enrichment of unique LRP6 variants in TA patients but not in nonsyndromic OFC patients. Of the five variants in patients with TA, two affected the canonical splice site and three were missense variants; all variants segregated with the dominant phenotype, and in one case the missense mutation occurred de novo.Mutations in LRP6 cause TA in humans.Genet Med 18 11, 1158-1162.
| S-EPMC5018235 | biostudies-literature
Project description:BackgroundThe low-density lipoprotein receptor-related protein 6 (LRP6) gene is a recently defined gene that is associated with the autosomal-dominant inherited tooth agenesis (TA). In the present study, a family of four generations having TA was recruited and subjected to a series of clinical, genetic, in silico, and in vitro investigations.MethodsAfter routine clinical evaluation, the proband was subjected to whole-exome sequencing (WES) to detect the diagnostic variant. Next, in silico structural and molecular dynamics (MD) analysis was conducted on the identified novel missense variant for predicting its intramolecular impact. Subsequently, an in vitro study was performed to further explore the effect of this variant on protein maturation and phosphorylation.ResultsWES identified a novel variant, designated as LRP6: c.2570G > A (p.R857H), harbored by six members of the concerned family, four of whom exhibited varied TA symptoms. The in silico analysis suggested that this novel variant could probably damage the Wnt bonding function of the LRP6 protein. The experimental study demonstrated that although this novel variant did not affect the LRP6 gene transcription, it caused a impairment in the maturation and phosphorylation of LRP6 protein, suggesting the possibility of the disruption of the Wnt signaling.ConclusionThe present study expanded the mutation spectrum of human TA in the LRP6 gene. The findings of the present study are insightful and conducive to understanding the functional significance of specific LRP6 variants.
| S-EPMC8292820 | biostudies-literature
Project description:Background and purpose - Preaxial polydactyly of the foot is a rare malformation and clinicians are often unfamiliar with the associated malformations and syndromes. In order to give guidelines for diagnostics and referral to a clinical geneticist, we provide an overview of the presentation using a literature review and our own patient population. Patients and methods - The literature review was based on the Human Phenotype Ontology (HPO) project. From the HPO dataset, all phenotypes describing preaxial polydactyly were obtained and related diseases were identified and selected. An overview was generated in a heatmap, in which the phenotypic contribution of 12 anatomical groups to each disease is displayed. Clinical cases were obtained from our hospital database and were reviewed in terms of phenotype, genotype, heredity, and diagnosed syndromes. Results - From the HPO dataset, 21 diseases were related to preaxial polydactyly of the foot. The anatomical groups with the highest phenotypic contribution were lower limb, upper limb, and craniofacial. From our clinical database, we included 76 patients with 9 different diseases, of which 27 had a GLI3 mutation. Lower limb malformations (n = 55), upper limb malformations (n = 59), and craniofacial malformations (n = 32) were most frequently observed. Malformations in other anatomical groups were observed in 27 patients. Interpretation - Preaxial polydactyly of the foot often presents with other upper and lower limb malformations. In patients with isolated preaxial polydactyly of the foot, referral to a clinical geneticist is not mandatory. In patients with additional malformations, consultation with a clinical geneticist is recommended. When additional limb malformations are present, analysis of GLI3 is most feasible.
| S-EPMC5810818 | biostudies-other
Project description:We present association results from a large genome-wide association study of tooth agenesis (TA) as well as selective TA, including 1,944 subjects with congenitally missing teeth, excluding third molars, and 338,554 controls, all of European ancestry. We also tested the association of previously identified risk variants, for timing of tooth eruption and orofacial clefts, with TA. We report associations between TA and 9 novel risk variants. Five of these variants associate with selective TA, including a variant conferring risk of orofacial clefts. These results contribute to a deeper understanding of the genetic architecture of tooth development and disease. The few variants previously associated with TA were uncovered through candidate gene studies guided by mouse knockouts. Knowing the etiology and clinical features of TA is important for planning oral rehabilitation that often involves an interdisciplinary approach.
| S-EPMC5958369 | biostudies-literature
Project description:Background: Preaxial polydactyly (PPD) is one of the most common developmental malformations, with a prevalence of 0.8-1.4% in Asians. PPD is divided into four types, PPD I-IV, and PPD I is the most frequent type. Only six loci (GLI1, GLI3, STKLD1, ZRS, pre-ZRS, and a deletion located 240 kb from SHH) have been identified in non-syndromic PPD cases. However, pathogenesis of most PPD patients has never been investigated. This study aimed to understand the genetic mechanisms involved in the etiology of PPD I in a family with multiple affected members. Methods: We recruited a PPD I family (PPD001) and used stepwise genetic analysis to determine the genetic etiology. In addition, for functional validation of the identified GLIS1 variant, in vitro studies were conducted. GLIS1 variants were further screened in additional 155 PPD cases. Results: We identified a GLIS1 variant (NM_147193: c.1061G > A, p.R354H) in the PPD001 family. In vitro studies showed that this variant decreased the nuclear translocation of GLIS1 and resulted in increased cell viability and migration. RNA sequencing revealed abnormal TBX4 and SFRP2 expression in 293T cells transfected with mutant GLIS1. Additionally, we identified a GLIS1 variant (c.664G > A, p.D222N) in another PPD case. Conclusion: We identified two GLIS1 variants in PPD I patients and first linked GLIS1 with PPD I. Our findings contributed to future molecular and clinical diagnosis of PPD and deepened our knowledge of this disease.
| S-EPMC8787328 | biostudies-literature
Project description:Tooth agenesis is one of the most common developmental anomalies affecting function and esthetics. The paired-domain transcription factor, Pax9, is critical for patterning and morphogenesis of tooth and taste buds. Mutations of PAX9 have been identified in patients with tooth agenesis. Despite significant progress in the genetics of tooth agenesis, many gaps in knowledge exist in refining the genotype-phenotype correlation between PAX9 and tooth agenesis. In the present study, we complete genetic and phenotypic characterization of multiplex Chinese families with nonsyndromic (NS) tooth agenesis. Direct sequencing of polymerase chain reaction products revealed 9 novel (c.140G>C, c.167T>A, c.332G>C, c.194C>A, c.271A>T, c.146delC, c.185_189dup, c.256_262dup, and c.592delG) and 2 known heterozygous mutations in the PAX9 gene among 120 probands. Subsequently, pedigrees were extended, and we confirmed that the mutations co-segregated with the tooth agenesis phenotype (with exception of families in which DNA analysis was not available). In 1 family ( n = 6), 2 individuals harbored both the PAX9 c.592delG mutation and a heterozygous missense mutation (c.739C>T) in the MSX1 gene. Clinical characterization of families segregating a PAX9 mutation reveal that all affected individuals were missing the mandibular second molar and their maxillary central incisors are most susceptible to microdontia. A significant reduction of bitter taste perception was documented in individuals harboring PAX9 mutations ( n = 3). Functional studies revealed that PAX9 haploinsufficiency or a loss of function of the PAX9 protein underlies tooth agenesis.
| S-EPMC5784472 | biostudies-literature
Project description:Mutations in the long-range limb-specific cis-regulator (ZRS) could cause ectopic shh gene expression and are responsible for preaxial polydactyly (PPD). In this study, we analyzed a large Chinese isolated autosomal dominant PPD pedigree. By fine mapping and haplotype construction, we located the linked region to a 1.7 cM interval between flanking markers D7S2465 and D7S2423 of chromosome 7q36. We directly sequenced the candidate loci in this linked region, including the coding regions of the five genes (HLXB9, LMBR1, NOM1, RNF32 and C7orf13), the regulatory element (ZRS) of shh, the whole intron 5 of LMBR1 which contained the ZRS, and 18 conserved noncoding sequences (CNSs). Interestingly, no pathogenic mutation was identified. By using real-time quantitative PCR (qPCR), we also excluded the ZRS duplication in this pedigree. Our results indicate that, at least, it is not the mutation in a functional gene, CNS region or duplication of ZRS that cause the phenotype of this pedigree. The etiology of this PPD family still remains unclear and the question whether another limb-specific regulatory element of shh gene exists in the noncoding region in this 1.7 cM interval remains open for future research.
| S-EPMC2986254 | biostudies-literature
Project description:The aim of the present study was to assess if genetic polymorphisms in tooth agenesis (TA)-related genes are associated with craniofacial morphological patterns. This cross-sectional, multi-center, genetic study evaluated 594 orthodontic Brazilians patients. The presence or absence of TA was determined by analysis of panoramic radiography. The patients were classified according to their skeletal malocclusion and facial growth pattern by means of digital cephalometric analysis. Genomic DNA was extracted from squamous epithelial cells of buccal mucosa and genetic polymorphisms in MSX1 (rs1042484), PAX9 (rs8004560), TGF-α (rs2902345), FGF3 (rs1893047), FGF10 (rs900379), and FGF13 (rs12838463, rs5931572, and rs5974804) were genotyped by polymerase chain reaction using TaqMan chemistry and end-point analysis. Genotypes (p = 0.038) and allele (p = 0.037) distributions for the FGF3 rs1893047 were significantly different according to the skeletal malocclusion. Carrying at least one G allele increased in more than two times the chance of presenting skeletal class III malocclusion (OR = 2.21, CI 95% = 1.14-4.32; p = 0.017). There was no association between another skeletal craniofacial pattern and some polymorphism assessed in the present study. Our results suggest that the genetic polymorphism rs1893047 in FGF3 might contribute to variations in the craniofacial sagittal pattern.
| S-EPMC7131971 | biostudies-literature