Rare compound heterozygous variants of LAMB3 and histological features of enamel and oral mucosa.

Junctional epidermolysis bullosa (JEB) is a group of autosomal recessive disorders characterized by amelogenesis imperfecta (AI) and fragility of the skin and mucous membranes. The purpose of this study was to identify pathogenic gene variants and investigate the phenotypic characteristics of abnormal enamel structure and mucocutaneous lesions in a patient with JEB. Clinical examination of the patient revealed hypoplastic AI, skin lesions, and oral ulcers, whereas her parents were normal. Whole-exome sequencing (WES) and cDNA cloning identified compound heterozygous variants of LAMB3 in the proband: c.125G>C in exon 3, c.1288 + 1G>A in intron 11, and c.1348C>T in exon 12. Among these, c.125G>C was inherited from her father, and the other two variants were inherited from her mother. Functional prediction indicated that the variants might change protein structure and cause disease. Scanning electron microscopy (SEM) examination of the primary and permanent teeth revealed abnormal enamel morphology and microstructures. Hematoxylin-eosin (HE) and immunofluorescence (IF) staining showed significantly abnormal and disorganized epithelial cells in the gingival mucosa. Our results showed that this was a case of intermediate JEB1A (OMIM #226650) with autosomal recessive inheritance. The proband carried rare compound heterozygous variants of LAMB3. Our results broaden the variant spectrum of the LAMB3 gene and JEB cases. Moreover, this is the first study to identify histological malformations of the primary teeth and oral mucosa in LAMB3-related patients.

Rare phenotype: Hand preaxial polydactyly associated with LRP6-related tooth agenesis in humans.

Low-density lipoprotein receptor-related protein 6 (LRP6) is a pathogenic gene of selective tooth agenesis-7 (OMIM#616724). Although the malformation of the digits and fore- and hindlimbs has been reported in Lrp6-deficient mice, it has been rarely discovered in humans with LRP6 mutations. Here, we demonstrate an unreported autosomal dominant LRP6 heterozygous mutation (c.2840 T > C;p.Met947Thr) in a tooth agenesis family with hand polydactyly, and another unreported autosomal dominant LRP6 heterozygous mutation (c.1154 G > C;p.Arg385Pro) in a non-syndromic tooth agenesis family. Bioinformatic prediction demonstrated the deleterious effects of the mutations, and LRP6 structure changes suggested the corresponding functional impairments. Analysis on the pattern of LRP6-related tooth agenesis demonstrated the maxillary lateral incisor was the most affected. Our study report that LRP6 mutation might be associated with hand preaxial polydactyly in humans, which broaden the phenotypic spectrum of LRP6-related disorders, and provide valuable information on the characteristics of LRP6-related tooth agenesis.

Establishing a warning index for evaluating the physiological stress of sanitation workers in high temperature weather.

High temperature weather occurs frequently in recent years. As a heat-vulnerable group, sanitation workers suffer great physiological safety risks in high temperature weather. In this paper, a physiological warning index (PWI) is established to quantify the physiological stress of the sanitation workers. Firstly, the dynamic weights of the physiological parameters are calculated by the norm grey correlation method. Secondly, the PWI is established by the efficacy coefficient method and the warning level of the PWI is divided based on the relationships between the PWI and thermal sensation vote (TSV). Finally, the reasonability of the PWI is verified. The results show that the weights of the physiological parameters are dynamic, changing with the environments and the physiological states. The weight ranges of the mean skin temperature (MST), tympanic temperature (TT), systolic blood pressure (SBP), diastolic blood pressure (DBP) and heart rate (HR) are 0.036-0.538, 0.000-0.369, 0.000-0.362, 0.018-0.367 and 0.009-0.348. And the MST and DBP are more affected by the high temperature than the TT, SBP and HR. The warning interval of PWI is: (0, 0.25] (no warning), (0.25, 0.45] (mild warning), (0.45, 0.7] (moderate warning), and (0.7, 1.0] (severe warning). The PWI can provide simple real-time physiological warning and guarantee physiological health for sanitation workers in high temperature weather.

Effects of Co Addition on the Microstructure and Properties of Elastic Cu-Ni-Si-Based Alloys for Electrical Connectors.

The properties and microstructure evolution of quaternary Cu-Ni-Co-Si alloys with different Ni/Co mass ratios were investigated. The microstructure and morphological characteristics of the precipitates were analyzed by using electron backscatter diffraction (EBSD), transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HRTEM). The mechanical properties and conductivity of the alloys were significantly improved after the addition of Co. The grains presented an obvious growth trend with an increase in Ni/Co mass ratios, and the appropriate Co accelerated the recrystallization process. The δ-(Ni, Co)2Si phases of the Cu-Ni-Co-Si alloys and δ-Ni2Si phases of the Cu-Ni-Si alloys shared the same crystal structure and orientation relationships with the matrix, which had two variant forms: δ1 and δ2 phases. The precipitates preferential grew along with the direction of the lowest energy and eventually exhibited two different morphologies. Compared with that of the Cu-Ni-Si alloy, the volume fraction of precipitates in the alloys with Co was significantly improved, accompanied by an increase in the precipitated phase size. The addition of Co promoted the precipitation of the precipitated phase and further purified the matrix. A theoretical calculation was conducted for different strengthening mechanisms, and precipitation strengthening was the key reinforcement mechanism. Moreover, the kinetic equations of both alloys were obtained and coincided well with the experimental results.

Comparative analysis of rare EDAR mutations and tooth agenesis pattern in EDAR- and EDA-associated nonsyndromic oligodontia.

Nonsyndromic oligodontia is a rare congenital anomaly. Mutations in the ectodysplasin A receptor (EDAR) gene are the primary cause of hypohidrotic ectodermal dysplasia but are rarely reported in nonsyndromic oligodontia. This study investigated EDAR mutations in multiplex nonsyndromic oligodontia and comparatively analyzed the EDAR- and EDA-related tooth agenesis patterns. Mutation screening was carried out using whole-exome sequencing and familial segregation. Evolutionary conservation and conformational analyses were used to evaluate the potential pathogenic influence of EDAR mutants. EDAR mutations were found to occur in 10.7% of nonsyndromic oligodontia cases. We reported seven heterozygous mutations of EDAR, including five novel mutations (c.404G>A, c.871G>A, c.43G>A, c.1072C>T, and c.1109T>C) and two known mutations (c.319A>G and c.1138A>C). Genotype-phenotype correlation analysis demonstrated that the EDAR-related tooth agenesis pattern was markedly different from EDA. The mandibular second premolars were most frequently missing (57.69%) in EDAR-mutated patients. Our results provide new evidence for the genotypic study of nonsyndromic oligodontia and suggest that EDAR haploinsufficiency results in nonsyndromic tooth agenesis. Furthermore, the distinct pattern between EDAR- and EDA-related tooth agenesis can be used as a guide for mutation screening during the clinical genetic diagnosis of this genetic disorder.

Novel PITX2 mutations identified in Axenfeld-Rieger syndrome and the pattern of PITX2-related tooth agenesis.

OBJECTIVES: To investigate the mutations in patients with Axenfeld-Rieger syndrome (ARS) and the pattern of PITX2-related tooth agenesis. METHODS: Whole-exome sequencing (WES) and copy number variation (CNV) array were used to screen the mutations in four ARS probands. After Sanger sequencing and quantitative polymerase chain reaction (qPCR) validation, secondary structure prediction and dual-luciferase assay were employed to investigate the functional impact. Eighteen PITX2-mutated patients with definite dental records were retrieved from our database and literatures, and the pattern of PITX2-related tooth agenesis was analyzed. RESULTS: A novel de novo segmental deletion of chromosome 4q25 (GRCh37/hg19 chr4:111, 320, 052-111, 754, 236) encompassing PITX2 and three novel PITX2 mutations c.148C > T, c.257G > A, and c.630insCG were identified. Preliminary functional studies indicated the transactivation capacity of mutant PITX2 on Distal-less homeobox 2 (DLX2) promoter was compromised. The maxillary teeth showed significantly higher rate of agenesis (57.94%) than the mandibular teeth (44.05%). The most often missing teeth were upper lateral incisors (83.33%) and upper second premolars (69.44%). Teeth with the least agenesis rate were the lower second molars (19.44%) and lower first molars (8.33%). CONCLUSIONS: We identified a novel 4q25 microdeletion including PITX2 and three novel PITX2 mutations, and statistically analyzed the PITX2-related tooth agenesis pattern.

DLX3 regulates osteogenic differentiation of bone marrow mesenchymal stem cells via Wnt/ß-catenin pathway mediated histone methylation of DKK4.

OBJECTIVE: Distal-less homeobox 3 (DLX3) is an important transcription factor involved in the osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs). However, the underlying mechanism is not clear. This study investigated the underlying mechanism of DLX3 in osteogenic differentiation. METHODS: DLX3 overexpression and knockdown in cells were achieved using lentiviruses. The osteogenic differentiation of BMSCs was detected using alkaline phosphatase expression, alizarin red staining, real-time quantitative polymerase chain reaction (RT-qPCR), Western blotting, and chromatin immunoprecipitation (ChIP) assays. RESULTS: DLX3 overexpression promoted the osteogenic differentiation of BMSCs, whereas DLX3 knockdown reduced the osteogenic differentiation of BMSCs. RT-qPCR and Western blotting assays showed that DLX3 modulated osteogenic differentiation via the Wnt/ß-catenin pathway. ChIP-qPCR showed that DLX3 knockdown promoted DKK4 expression by decreasing the enrichment of histone H3 lysine 27 trimethylation (H3K27me3) in the promotor region of DKK4. CONCLUSION: Our data implied that DLX3 regulated Wnt/ß-catenin pathway through histone modification of DKK4 during the osteogenic differentiation of BMSCs.

BMP4 mutations in tooth agenesis and low bone mass.

OBJECTIVE: To identify an uncommon genetic cause of tooth agenesis (TA) by utilizing whole exome sequencing (WES) and targeted Sanger sequencing in a cohort of 120 patients with isolated TA. DESIGN: One deleterious mutation in the gene encoding bone morphogenetic protein 4 (BMP4) was identified in 6 unrelated patients with TA by WES. After that, the coding exons of BMP4 were examined in 114 TA patients using Sanger sequencing. Dual-energy X-ray absorptiometry (DEXA) was used to measure the bone mineral density of patients who carried a BMP4 mutation. Finally, preliminary functional studies of two BMP4 mutants were performed. RESULTS: We detected 3 novel missense mutations (c.58 G > A: p.Gly20Ser, c.326 G > T: p.Arg109Leu and c.614 T > C: p.Val205Ala) and 1 reported mutation in the BMP4 gene among 120 TA probands. The previously reported BMP4 mutation (c.751C > T: p.His251Tyr) was associated with urethra and eye anomalies. By extending the pedigrees, we determined that the tooth phenotypes had an autosomal dominant inheritance pattern, as individuals carrying a BMP4 mutation exhibit different types of dental anomalies. Interestingly, we observed that patients harboring a BMP4 mutation manifested early onset osteopenia or osteoporosis. Further in vitro functional assays demonstrated that two BMP4 mutants resulted in a decreased activation of Smad signaling. Therefore, a loss-of-function in BMP4 may contribute to the clinical phenotypes seen in this study. CONCLUSIONS: We identified 4 mutations in the BMP4 gene in 120 TA patients. To our knowledge, this is the first study to describe human skeletal diseases associated with BMP4 mutations.