Mutation spectrum of hearing loss patients in Northwest China: Identification of 20 novel variants.

BACKGROUND: Hearing loss (HL) is the most frequent sensory deficit in humans, with strong genetic heterogeneity. The genetic diagnosis of HL is very important to aid treatment decisions and to provide prognostic information and genetic counselling for the patient's family. METHODS: We detected and analysed 362 Chinese non-syndromic HL patients by screening of variants in 15 hot spot mutations. Subsequently, 40 patients underwent further whole-exome sequencing (WES) to determine genetic aetiology. The candidate variants were verified using Sanger sequencing. Twenty-three carrier couples with pathogenic variants or likely pathogenic variants chose to proceed with prenatal diagnosis using Sanger sequencing. RESULTS: Among the 362 HL patients, 102 were assigned a molecular diagnosis with 52 different variants in 22 deafness genes. A total of 41 (11.33%) cases with the biallelic GJB2 (OMIM # 220290) gene mutations were detected, and 21 (5.80%) had biallelic SLC26A4 (OMIM # 605646) mutations. Mitochondrial gene (OMIM # 561000) mutations were detected in seven (1.93%) patients. Twenty of the variants in 15 deafness genes were novel. SOX10 (OMIM # 602229), MYO15A (OMIM # 602666) and WFS1 (OMIM # 606201) were each detected in two patients. Meanwhile, OSBPL2 (OMIM # 606731), RRM2B (OMIM # 604712), OTOG (OMIM # 604487), STRC (OMIM # 606440), PCDH15 (OMIM # 605514), LOXHD1 (OMIM # 613072), CDH23 (OMIM # 605516), TMC1 (OMIM # 606706), CHD7 (OMIM # 608892), DIAPH3 (OMIM # 614567), TBC1D24 (OMIM # 613577), TIMM8A (OMIM # 300356), PTPRQ (OMIM # 603317), SALL1 (OMIM # 602218), and GSDME (OMIM # 608798) were each detected in one patient. In addition, as regards one couple with a heterozygous variant of CDH23 and PCDH15, respectively, prenatal diagnosis results suggest that the foetus had double heterozygous (DH) variants of CDH23 and PCDH15, which has a high risk to cause ID/F type Usher syndrome. CONCLUSION: Our study expanded the spectrum of deafness gene variation, which will contribute to the genetic diagnosis, prenatal diagnosis and the procreation guidance of deaf couple. In addition, the deafness caused by two genes should be paid attention to in the prenatal diagnosis of families with both deaf patients.

The effects of dehiscence and fenestration before orthodontic treatment on external apical root resorption in maxillary incisors.

INTRODUCTION: The objective of this study was to investigate the effects of dehiscence and fenestration on external apical root resorption (EARR) in maxillary incisors. METHODS: Seventy-eight patients were selected for this study. We set dehiscence, fenestration, sex, extraction, or nonextraction, tooth position, initial age, and duration of treatment as independent variables and EARR as the dependent variable. General statistical descriptions for these variables were made by mean, standard deviation and occurrence rates, etc. To make the data visualization and find more information, 2 heat maps were made. Generalized estimation equation analysis was performed to determine associations between EARR and independent variables. RESULTS: The occurrence rates of dehiscence and fenestration in maxillary incisors were 14.77% and 10.74%, respectively. The average value of EARR was 1.09 ± 0.87 mm in this study. Dehiscence, tooth position, extraction, initial age, and duration had significant correlations with EARR. The ratio of exponent B was 1:1.643 for dehiscence and nondehiscence, whereas fenestration and sex had no significant association with EARR. CONCLUSIONS: The amount of EARR at maxillary incisors in patients with dehiscence before orthodontic treatment might be less than that in patients without it, and different incisors might have different contributions to it. However, the low value of exponent B for dehiscence meant that there might be other unknown factors that were involved in this study.

Evaluation of palatal support tissues for placement of orthodontic mini-implants in mouth breathers with high-narrow palates versus nose breathers with normal palates: a retrospective study.

OBJECTIVES: The aim of this study was to compare the palatal total support tissues (TSTs) and bone support tissues (BSTs) at 5-mm paramedian section to the midsagittal suture between mouth breathers with high-narrow palates and nose breathers with normal palates and confirm the practicability and limitation on superimposition of lateral cephalograms and plaster models for orthodontic mini-implant (OMI) implantation in these patients. MATERIAL AND METHODS: The sample consisted of 27 mouth breathers with high-narrow palates (study group (SG)) and 27 nose breathers with normal palates (control group (CG)). Upper digital dental models were superimposed with corresponding cone beam computed tomography (CBCT) images; then, TSTs and BSTs vertical to the curvature of the palatal mucosa were measured on the 5-mm paramedian section to the midsagittal suture. The measuring sites were the third ruga (R) and the sites anterior and posterior to R at 2-mm interval (A2, A4, A6, and A8; P2, P4, P6, and P8) along the palatal mucosa outline. TSTs and BSTs were also measured on the superimposition of lateral cephalograms and plaster models, and the site with the largest TST value in each patient was recorded. Descriptive statistics, independent-samples t test, and hierarchical clustering heat map were used for statistical analysis. RESULTS: The greatest average values of TSTs and BSTs in SG were 12.24 ± 2.63 mm and 9.59 ± 2.36 mm at P2 site, and those in CG were 12.96 ± 2.39 mm and 10.56 ± 2.38 mm at R site, respectively. The average values of both TSTs and BSTs in SG were less than those in CG at all insertion sites. Significant differences (P < 0.05) were found at A4, A6, and R for TSTs and at R and P4 for BSTs. P2 and R were clustered together for both TSTs and BSTs by the cluster analysis on heat map in both SG and CG. In both groups, only one patient from SG was found to have the insertion site with the largest TST value on 2D superimposition located in the blue area on the heat map, where the measurement values of TSTs were less than 8.5 mm and those of BSTs were less than 5 mm. CONCLUSIONS: Mouth breathers with high-narrow palates may have less palatal support tissues than nose breathers with normal palates at 5-mm paramedian section to the midsagittal suture of palate. The site a little posterior to R is more suitable for OMI implantation in mouth breathers. Two-dimensional superimposition of lateral cephalograms and plaster models can provide relatively effective assessment for the site choice of OMI implantation in both mouth breathers with high-narrow palates and nose breathers with normal palates. CLINICAL RELEVANCE: Three-dimensional superimposition of CBCT data and digital dental model can provide accurate information for palatal OMI implantation. Meanwhile, 2D superimposition of lateral cephalograms and plaster models can be used for assessing the implantation sites at 5-mm paramedian section to the midsagittal suture of palates in mouth breathers under most conditions even those who have less palatal support tissues.

[Evaluation of dental and craniofacial characteristics in patients with mild skeletal facial asymmetry].

PURPOSE: The purpose of this study was to investigate the dental and craniofacial morphological characteristics in patients with mild skeletal facial asymmetry, and to investigate the relationship between mild skeletal facial asymmetry and dental anomalies. METHODS: Thirty patients with mild skeletal facial asymmetry (experimental group) and 30 patients with normal faces (control group) were selected. All patients were scanned by cone-beam computed tomography (CBCT) and X-ray machine, Winceph software was used to measure the posteroanterior cephalometric radiographs, NNT software was used to measure the CBCT data. The results were analyzed by Chi-square test, paired t test and independent sample t test using SPSS 19.0 software package. RESULTS: There were significant differences between the left and right sides of faces, teeth and alveolar bone of the first molar in the experimental group. The angle of mandibular dental midline and facial midline, the inclination of the frontal mandibular plane, the inclination of the first molar, the inclination of alveolar bone of the mandibular first molar, the width of alveolar bone of the mandibular first molar showed significant differences between the experimental group and the control group (P<0.05). There are some correlations among menton deviation, inclination of the first molar and alveolar bone of the first molar. CONCLUSIONS: Patients with mild skeletal facial asymmetry showed some specific skeletal and dental characteristics. There could be some correlations between these features．.