BACKGROUND: Congenital sensorineural hearing loss is a significant global health issue, primarily driven by genetic factors, such as mutations in the GJB2 gene. This report presents a Chinese girl with congenital deafness and a novel mutation of the GJB2 gene.
METHODS: A newborn Chinese girl exhibited signs of congenital deafness.
METHODS: Congenital deafness was confirmed through comprehensive newborn hearing screenings that included otologic, audiologic, and physical examinations. Genetic analysis revealed a compound heterozygous mutation involving c.188delT and c.235delC in the GJB2 gene, indicating a genetic basis for her hearing loss.
METHODS: The patient underwent cochlear implantation, which resulted in stable auditory outcomes.
RESULTS: Despite follow-up difficulties, stable auditory outcomes were achieved post-cochlear implantation, highlighting the potential efficacy of this intervention in GJB2-related hearing loss.
CONCLUSIONS: This case study enriches our understanding of GJB2 mutations and underscores the critical role of genetic testing in diagnosing congenital sensorineural hearing loss. It emphasizes the necessity for early intervention and sustained interdisciplinary care to enhance the quality of life for patients with genetic hearing impairment.

OBJECTIVE: To investigate the epidemiological characteristics and mutation spectrum of monogenic diseases in Chinese population through a large-scale, multicenter carrier screening.
METHODS: This study was conducted among a total of 33 104 participants (16 610 females) from 12 clinical centers across China.Carrier status for 223 genes was analyzed using high-throughput sequencing and different PCR methods.
RESULTS: The overall combined carrier frequency was 55.58% for 197 autosomal genes and 1.84% for 26 X-linked genes in these participants.Among the 16 669 families, 874 at-risk couples (5.24%) were identified.Specifically, 584 couples (3.50%) were at risk for autosomal genes, 306(1.84%) for X-linked genes, and 16 for both autosomal and X-linked genes.The most frequently detected autosomal at-risk genes included GJB2(autosomal recessive deafness type 1A, 393 couples), HBA1/HBA2(α-thalassemia, 36 couples), PAH (phenylketonuria, 14 couples), and SMN1(spinal muscular atrophy, 14 couples).The most frequently detected X-linked at-risk genes were G6PD (G6PD deficiency, 236 couples), DMD (Duchenne muscular dystrophy, 23 couples), and FMR1(fragile X syndrome, 17 couples).After excluding GJB2 c.109G>A, the detection rate of at-risk couples was 3.91%(651/16 669), which was lowered to 1.72%(287/16 669) after further excluding G6PD.The theoretical incidence rate of severe monogenic birth defects was approximately 4.35‰(72.5/16 669).Screening for a battery of the top 22 most frequent genes in the at-risk couples could detect over 95% of at-risk couples, while screening for the top 54 genes further increased the detection rate to over 99%.
CONCLUSIONS: This study reveals the carrier frequencies of 223 monogenic genetic disorders in the Chinese population and provides evidence for carrier screening strategy development and panel design tailored to the Chinese population.In carrier testing, genetic counseling for specific genes or gene variants can be challenging, and the couples need to be informed of these difficulties before testing and provided with options for not screening these genes or gene variants.

OBJECTIVE: The aim of this study was to explore the functional consequences of two common variants, p.V37I and c.299-300delAT, in the hearing loss-associated gene GJB2.
METHODS: Connexin 26 expression and gap junctional permeability were studied in HEK 293T cells transfected with plasmids expressing GJB2 wild-type, p.V37I, or c.299-300delAT CX26 proteins tagged with fluorescent markers. Functional analyses of various GJB2 haplotypes were conducted to thoroughly evaluate alterations in ionic and small-molecule coupling.
RESULTS: The p.V37I protein was localized at the plasma membrane, but it failed to effectively transport intercellular propidium iodide or Ca2+ efficiently, indicating an impairment in both biochemical and ionic coupling. The presence of GJB2 p.V37I seemed to increase the cells\' sensitivity to H2O2 treatment. In contrast, the known variant c.299-300delAT protein was not transported to the cell membrane and was unable to form gap junctions, remaining confined to the cytoplasm. Both ionic and biochemical coupling were defective in cells transfected with c.299-300delAT.
CONCLUSIONS: The p.V37I and c.299-300delAT GJB2 mutations resulted in deficient gap junction-mediated coupling. Additionally, environmental factors could influence the functional outcomes of the GJB2 p.V37I mutation. These findings could pave the way for the development of molecular therapies targeting GJB2 mutations to treat hearing loss.

Hearing loss constitutes one of the most prevalent conditions within the field of otolaryngology. Recent investigations have revealed that mutations in deafness-associated genes, including point mutations and variations in DNA sequences, can cause hearing impairments. With the ethology of deafness remaining unclear for a substantial portion of the affected population, further screenings for pathogenic mutations are imperative to unveil the underlying mechanisms. On this study, by using next-generation sequencing, we examine 129 commonly implicated deafness-related genes in a Chinese family with hearing loss, revealing a novel heterozygous dominant mutation in the GJB2 gene (GJB2: c.65T>G: p. Lys22Thr). This mutation consistently occurs in affected family members but is not detected in unaffected individuals, strongly suggesting its causative role in hearing loss. Structural analysis indicates potential disruption to the Cx26 gap junction channel\'s hydrogen bond and electrostatic interactions, aligning with predictions from the PolyPhen and SIFT algorithms. In conclusion, our study provides conclusive evidence that the identified heterozygous GJB2 mutation (GJB2: c.65T>G: p. Lys22Thr), specifically the K22T alteration, is the primary determinant of the family\'s deafness. This contribution enhances our understanding of the interplay between common deafness-associated genes and hearing loss, offering valuable insights for diagnostic guidance and the formulation of therapeutic strategies for this condition.

OBJECTIVE: To analyze the types and distribution of pathogenic variants for neonatal genetic diseases in Huzhou, Zhejiang Province.
METHODS: One thousand neonates (48 ~ 42 h after birth) born to Huzhou region were selected as the study subjects. Dry blood spot samples were collected from the newborns, and targeted capture high-throughput sequencing was carried out for pathogenic genes underlying 542 inherited diseases. Candidate variants were verified by Sanger sequencing.
RESULTS: Among the 1 000 newborns, the male to female ratio was 1.02 : 1.00. No pathogenic variants were detected in 253 cases, whilst 747 cases were found to carry at least one pathogenic variant, which yielded a carrier rate of 74.7%. The most frequently involved pathogenic gene was FLG, followed by GJB2, UGT1A1, USH2A and DUOX2. The variants were classified as homozygous, compound heterozygous, and hemizygous variants. Based on the guidelines from the American College of Medical Genetics and Genomics (ACMG), 213 neonates were verified to have carried pathogenic and/or likely pathogenic variants, with a positive rate of 21.3%. The most commonly involved genes had included UGT1A1, FLG, GJB2, MEFV and G6PD.
CONCLUSIONS: Newborn screening based on high-throughput sequencing technology can expand the scope of screening and improve the positive predictive value. Genetic counseling based on the results can improve the patients\' medical care and reduce neonatal mortality and childhood morbidity, while provide assistance to family members\' health management and reproductive decisions.

Noninvasive prenatal diagnosis (NIPD) for autosomal recessive nonsyndromic hearing loss (ARNSHL) has been rarely reported until recent years. Additionally, the existing method can not be used for challenging genome loci (eg, copy number variations, deletions, inversions, or gene recombinants) or on families without proband genotype. This study assessed the performance of relative haplotype dosage analysis (RHDO)-based NIPD for identifying fetal genotyping in pregnancies at risk of ARNSHL. Fifty couples carrying pathogenic variants associated with ARNSHL in either GJB2 or SLC26A4 were recruited. The RHDO-based targeted linked-read sequencing combined with whole gene coverage probes was used to genotype the fetal cell-free DNA of 49 families who met the quality control standard. Fetal amniocyte samples were genotyped using invasive prenatal diagnosis (IPD) to assess the performance of NIPD. The NIPD results showed 100% (49/49) concordance with those obtained through IPD. Two families with copy number variation and recombination were also successfully identified. Sufficient specific informative single-nucleotide polymorphisms for haplotyping, as well as the fetal cell-free DNA concentration and sequencing depth, are prerequisites for RHDO-based NIPD. This method has the merits of covering the entire genes of GJB2 and SLC26A4, qualifying for copy number variation and recombination analysis with remarkable sensitivity and specificity. Therefore, it has clinical potential as an alternative to traditional IPD for ARNSHL.

This study aimed to develop and validate a prenatal cell-free DNA (cfDNA) screening method that uses capture-based enrichment to genotype fetal autosomal recessive disorders. This method was applied in pregnancies at high risk of autosomal recessive non-syndromic hearing loss (ARNSHL) to assess its accuracy and effectiveness.
This assay measured the allele counts in both white blood cell DNA and cfDNA from the blood samples of pregnant women using a capture-based next-generation sequencing method. It then applied a binomial model to infer the fetal genotypes with the maximum likelihood. Ninety-four pregnant couples that were carriers of variants of ARNSHL in GJB2 or SLC26A4 were enrolled. The fetal genotypes deduced using this screening method were compared with the results of genetic diagnosis using amniocentesis.
Of the 94 couples, 65 carried more than one variant, resulting in 170 single-nucleotide polymorphism (SNP) loci to be inferred in the fetuses. Of the 170 fetal SNP genotypes, 150 (88.2%) had high confidence calls and 139 (92.7%) of these matched the genotypes obtained by amniocentesis result. Out of the remaining 20 (11.8%) cases with low-confidence calls, only 14 (70.0%) were concordant with genetic diagnosis using amniocentesis. The concordance rate was 100% for sites where the maternal genotype was wild-type homozygous. The discordance was site-biased, with each locus showing a consistent direction of discordance. Genetic diagnosis identified a total of 19 wild-type homozygotes, 46 heterozygotes, 19 compound heterozygotes, and 10 pathogenic homozygotes. This screening method correctly genotyped 81.9% (77/94) of fetuses and demonstrated a sensitivity of 89.7% and a specificity of 89.2% for correctly identifying ARNSHL.
This capture-based method of prenatal screening by cfDNA demonstrated strong potential for fetal genotyping of autosomal recessive disorders.

BACKGROUND: Hmong-Mien (HM) speakers are linguistically related and live primarily in China, but little is known about their ancestral origins or the evolutionary mechanism shaping their genomic diversity. In particular, the lack of whole-genome sequencing data on the Yao population has prevented a full investigation of the origins and evolutionary history of HM speakers. As such, their origins are debatable.
RESULTS: Here, we made a deep sequencing effort of 80 Yao genomes, and our analysis together with 28 East Asian populations and 968 ancient Asian genomes suggested that there is a strong genetic basis for the formation of the HM language family. We estimated that the most recent common ancestor dates to 5800 years ago, while the genetic divergence between the HM and Tai-Kadai speakers was estimated to be 8200 years ago. We proposed that HM speakers originated from the Yangtze River Basin and spread with agricultural civilization. We identified highly differentiated variants between HM and Han Chinese, in particular, a deafness-related missense variant (rs72474224) in the GJB2 gene is in a higher frequency in HM speakers than in others.
CONCLUSIONS: Our results indicated complex gene flow and medically relevant variants involved in the HM speakers\' evolution history.

GJB2 gene mutations are the most common causes of autosomal recessive non-syndromic hereditary deafness. For individuals suffering from severe to profound GJB2-related deafness, cochlear implants have emerged as the sole remedy for auditory improvement. Some previous studies have highlighted the crucial role of preserving cochlear neural components in achieving favorable outcomes after cochlear implantation. Thus, we generated a conditional knockout mouse model (Cx26-CKO) in which Cx26 was completely deleted in the cochlear supporting cells driven by the Sox2 promoter. The Cx26-CKO mice showed severe hearing loss and massive loss of hair cells and Deiter\'s cells, which represented the extreme form of human deafness caused by GJB2 gene mutations. In addition, multiple pathological changes in the peripheral auditory nervous system were found, including abnormal innervation, demyelination, and degeneration of spiral ganglion neurons as well as disruption of heminodes in Cx26-CKO mice. These findings provide invaluable insights into the deafness mechanism and the treatment for severe deafness in Cx26-null mice.

Objective:To elucidate the correlation between the GJB2 gene and auditory neuropathy, aiming to provide valuable insights for genetic counseling of affected individuals and their families. Methods:The general information, audiological data（including pure tone audiometry, distorted otoacoustic emission, auditory brainstem response, electrocochlography）, imaging data and genetic test data of 117 auditory neuropathy patients, and the patients with GJB2 gene mutation were screened out for the correlation analysis of auditory neuropathy. Results:Total of 16 patients were found to have GJB2 gene mutations, all of which were pathogenic or likely pathogenic.was Among them, one patient had compound heterozygous variants GJB2[c. 427C>T][c. 358_360del], exhibiting total deafness. One was GJB2[c. 299_300delAT][c. 35_36insG]compound heterozygous variants, the audiological findings were severe hearing loss.The remaining 14 patients with GJB2 gene variants exhibited typical auditory neuropathy. Conclusion:In this study, the relationship between GJB2 gene and auditory neuropathy was preliminarily analyzed,and explained the possible pathogenic mechanism of GJB2 gene variants that may be related to auditory neuropathy.
目的：探究GJB2基因与听神经病之间的关系，为此类患者及家庭的遗传咨询提供参考。 方法：对117例听神经病患者的基本信息、听力学资料（包括纯音测听、畸变耳声发射、听性脑干反应、耳蜗电图）、影像学资料、遗传学检测等数据进行收集，并筛选出携带GJB2基因变异的患者对其进行听神经病相关分析。 结果：共计16例患者检出GJB2基因变异，变异位点致病性均为致病的或可能致病的，其中1例为GJB2[c.427C>T][c.358_360del]复合杂合变异，听力学表现为全聋，1例为GJB2[c.299_300delAT][c.35_36insG]复合杂合变异，听力学表现为重度听力损失，其余14例携带GJB2基因变异患者听力学表型均为典型听神经病。 结论：本研究初步分析了GJB2基因与听神经病的相关性，并阐述了GJB2基因变异可能与听神经病表型相关的致病机制。.