Objective To report the nationwide prevalence of dizziness and vestibular dysfunction in the Korean population and determine the associated factors. Design Cross-sectional analysis of a nationwide health survey. Methods We obtained data from the 2009 to 2010 Korea National Health and Nutrition Examination Surveys, which were cross-sectional surveys of the South Korean civilian, non-institutionalised population aged 40 years and older (N=3267). A field survey team performed interviews and physical examinations. Structured questionnaires were handed out and balance function tests using the modified Romberg test of standing balance on firm and compliant support surfaces were performed on participants. Failure on the modified Romberg test was regarded to indicate vestibular dysfunction. Results The prevalence of dizziness during the past year was 16.70% (95% CI 14.65% to 18.76%). The presence of vestibular dysfunction was noted in 1.84% (95% CI 1.18% to 2.51%). In addition, the prevalence of experiencing falls and positional dizziness were 1.46% (95% CI 0.87% to 2.06%) and 1.73% (95% CI 1.17% to 2.29%), respectively. Multivariable analysis revealed that dizziness was associated with increased age, female gender, hearing loss and stress. Vestibular dysfunction was associated with increased age, history of dizziness and hearing loss. Conclusions Vertigo and dizziness are the greatest contributors to the burden of disability in the aged population. Screening for dizziness and vestibular dysfunction, and management of associated factors might be important for improving compromised quality of life due to postural imbalance caused by vestibular problems.

Despite the prevalence of CDH23 mutations in East Asians, its large size hinders investigation. The pathologic mutation p.P240L in CDH23 is common in East Asians. However, whether this mutation represents a common founder or a mutational hot spot is unclear. The prevalence of CDH23 mutations with prelingual severe-to-profound sporadic or autosomal recessive sensorineural hearing loss (arSNHL) is unknown in Koreans. From September 2010 to October 2014, children with severe-to-profound sporadic or arSNHL without phenotypic markers, and their families, were tested for mutations in connexins GJB2, GJB6 and GJB3. Sanger sequencing of CDH23 p.P240L was performed on connexin-negative samples without enlarged vestibular aqueducts (EVA), followed by targeted resequencing of 129 deafness genes, including CDH23, unless p.P240L homozygotes were detected in the first screening. Four p.P240L-allele-linked STR markers were genotyped in 40 normal-hearing control subjects, and the p.P240L carriers in the hearing-impaired cohort, to identify the haplotypes. Four (3.1 %) of 128 children carried two CDH23 mutant alleles, and SLC26A4 and GJB2 accounted for 18.0 and 17.2 %, respectively. All four children showed profound nonsyndromic SNHL with minimal residual hearing. Interestingly, all had at least one p.P240L mutant allele. Analysis of p.P240L-linked STR markers in these children and other postlingual hearing-impaired adults carrying p.P240L revealed that p.P240L was mainly carried on a single haplotype. p.P240L contributed significantly to Korean pediatric severe arSNHL with a strong founder effect, with implications for future phylogenetic studies. Screening for p.P240L as a first step in GJB2-negative arSNHL Koreans without EVA is recommended.

Previously, we introduced a noninvasive prenatal testing (NIPT) protocol for diagnosing compound heterozygous autosomal recessive point mutations via maternal plasma DNA and simulated control genomic DNA sampling based on fetal DNA fraction. In our present study, we have improved our NIPT protocol to make it possible to diagnose homozygous autosomal recessive point mutations without the need to acquire fetal DNA fraction. Moreover, chi-squared test and empirical statistical range based on the proportion of mutant allele reads among the total reads served as the gatekeeping method. If this method yielded inconclusive results, then the Bayesian method was performed; final conclusion was drawn from the results of both methods. This protocol was applied to three families co-segregating congenital sensorineural hearing loss with monogenic homozygous mutations in prevalent deafness genes. This protocol successfully predicted the fetal genotypes from all families without the information about fetal DNA fraction using one-step dPCR reactions at least for these three families. Furthermore, we suspect that confirmatory diagnosis under this protocol is possible, not only by using picodroplet dPCR, but also by using the more readily available chip-based dPCR, making our NIPT protocol more useful in the diagnosis of autosomal recessive point mutations in the future.

Objectives. Because climatic and air-pollution factors are known to influence the occurrence of respiratory diseases, we used these factors to develop machine learning models for predicting the occurrence of respiratory diseases.Methods. We obtained the daily number of respiratory disease patients in Seoul. We used climatic and air-pollution factors to predict the daily number of patients treated for respiratory diseases per 10,000 inhabitants. We applied the relief-based feature selection algorithm to evaluate the importance of feature selection. We used the gradient boosting and Gaussian process regression (GPR) methods, respectively, to develop two different prediction models. We also employed the holdout cross-validation method, in which 75% of the data was used to train the model, and the remaining 25% was used to test the trained model. We determined the estimated number of respiratory disease patients by applying the developed prediction models to the test set. To evaluate the performance of each model, we calculated the coefficient of determination (R2) and the root mean square error (RMSE) between the original and estimated numbers of respiratory disease patients. We used the Shapley Additive exPlanations (SHAP) approach to interpret the estimated output of each machine learning model.Results. Features with negative weights in the relief-based algorithm were excluded. When applying gradient boosting to unseen test data, R2 and RMSE were 0.68 and 13.8, respectively. For GPR, the R2 and RMSE were 0.67 and 13.9, respectively. SHAP analysis showed that reductions in average temperature, daylight duration, average humidity, sulfur dioxide (SO2), total solar insolation amount, and temperature difference increased the number of respiratory disease patients, whereas increases in atmospheric pressure, carbon monoxide (CO), and particulate matter ≤2.5 μm in aerodynamic diameter (PM2.5) increased the number of respiratory disease patients.Conclusions. We successfully developed models for predicting the occurrence of respiratory diseases using climatic and air-pollution factors. These models could evolve into public warning systems.

MYO15A variants, except those in the N-terminal domain, have been shown to be associated with congenital or pre-lingual severe-to-profound hearing loss (DFNB3), which ultimately requires cochlear implantation in early childhood. Recently, such variants have also been shown to possibly cause moderate-to-severe hearing loss. Herein, we also demonstrate that some MYO15A mutant alleles can cause postlingual onset of progressive partial deafness. Two multiplex Korean families (SB246 and SB224), manifesting postlingual, progressive, partial deafness in an autosomal recessive fashion, were recruited. Molecular genetics testing was performed in two different pipelines, in a parallel fashion, for the SB246 family: targeted exome sequencing (TES) of 129 known deafness genes from the proband and whole exome sequencing (WES) of all affected subjects. Only the former pipeline was performed for the SB224 family. Rigorous bioinformatics analyses encompassing structural variations were executed to investigate any causative variants. In the SB246 family, two different molecular diagnostic pipelines provided exactly the same candidate variants: c.5504G > A (p.R1835H) in the motor domain and c.10245_10247delCTC (p.S3417del) in the FERM domain of MYO15A. In the SB224 family, c.9790C > T (p.Q3264X) and c.10263C > G (p.I3421M) in the FERM domain were detected as candidate variants. Some recessive MYO15A variants can cause postlingual onset of progressive partial deafness. The phenotypic spectrum of DFNB3 should be extended to include such partial deafness. The mechanism for a milder phenotype could be due to the milder pathogenic potential from hypomorphic alleles of MYO15A or the presence of modifier genes. This merits further investigation.