Screening Consanguineous Families for Hearing Loss Using the MiamiOtoGenes Panel

Genotype Characterization and MiRNA Expression Profiling in Usher Syndrome Cell Lines

Usher syndrome (USH) is an inherited disorder characterized by sensorineural hearing loss (SNHL), retinitis pigmentosa (RP)-related vision loss, and vestibular dysfunction. USH presents itself as three distinct clinical types, 1, 2, and 3, with no biomarker for early detection. This study aimed to explore whether microRNA (miRNA) expression in USH cell lines is dysregulated compared to the miRNA expression pattern in a cell line derived from a healthy human subject. Lymphocytes from USH patients and healthy individuals were isolated and transformed into stable cell lines using Epstein-Barr virus (EBV). DNA from these cell lines was sequenced using a targeted panel to identify gene variants associated with USH types 1, 2, and 3. Microarray analysis was performed on RNA from both USH and control cell lines using NanoString miRNA microarray technology. Dysregulated miRNAs identified by the microarray were validated using droplet digital PCR technology. DNA sequencing revealed that two USH patients had USH type 1 with gene variants in USH1B (MYO7A) and USH1D (CDH23), while the other two patients were classified as USH type 2 (USH2A) and USH type 3 (CLRN-1), respectively. The NanoString miRNA microarray detected 92 differentially expressed miRNAs in USH cell lines compared to controls. Significantly altered miRNAs exhibited at least a twofold increase or decrease with a p value below 0.05. Among these miRNAs, 20 were specific to USH1, 14 to USH2, and 5 to USH3. Three miRNAs that are known as miRNA-183 family which are crucial for inner ear and retina development, have been significantly downregulated as compared to control cells. Subsequently, droplet digital PCR assays confirmed the dysregulation of the 12 most prominent miRNAs in USH cell lines. This study identifies several miRNA signatures in USH cell lines which may have potential utility in Usher syndrome identification.

A review of the mechanisms underlying the role of the GIPC3 gene in hereditary deafness

The GAIP interacting protein c terminus (GIPC) genes encode a small family of proteins characterized by centrally located PDZ domains. GIPC3 encodes a 312 amino acid protein. Variants of human GIPC3 are associated with non-syndromic hearing loss. GIPC3 is one of over a hundred different genes with variants causing human deafness. Screening for variants of GIPC3 is essential for early detection of hearing loss in children and eventually treatment of deafness. Accordingly, this paper assesses the status of research developments on the role of GIPC3 in hereditary deafness and the effects of pathogenic variants on the auditory system.

Prevalence and Characteristics of STRC Gene Mutations (DFNB16): A Systematic Review and Meta-Analysis

Background: Mutations in the STRC (MIM 606440) gene, inducing DFNB16, are considered a major cause of mild–moderate autosomal recessive non-syndromic hearing loss (ARNSHL). We conducted a systematic review and meta-analysis to determine the global prevalence and characteristics of STRC variations, important information required for genetic counseling.

Methods: PubMed, Google Scholar, Medline, Embase, and Web of Science were searched for relevant articles published before January 2021.

Results: The pooled prevalence of DFNB16 in GJB2-negative patients with hearing loss was 4.08% (95% CI: 0.0289–0.0573), and the proportion of STRC variants in the mild–moderate hearing loss group was 14.36%. Monoallelic mutations of STRC were 4.84% (95% CI: 0.0343–0.0680) in patients with deafness (non-GJB2) and 1.36% (95% CI: 0.0025–0.0696) in people with normal hearing. The DFNB16 prevalence in genetically confirmed patients (non-GJB2) was 11.10% (95% CI: 0.0716–0.1682). Overall pooled prevalence of deafness–infertility syndrome (DIS) was 36.75% (95% CI: 0.2122–0.5563) in DFNB16. The prevalence of biallelic deletions in STRC gene mutations was 70.85% (95% CI: 0.5824–0.8213).

Conclusion: Variants in the STRC gene significantly contribute to mild–moderate hearing impairment. Moreover, biallelic deletions are a main feature of STRC mutations. Copy number variations associated with infertility should be seriously considered when investigating DFNB16.

Genetic screening techniques and diseases for neonatal genetic diseases

Neonatal genetic disease is currently screened mainly based on metabolite biochemical technology. The false positive rate of biochemical screening technology is relatively high, and there are certain false negatives, and only few types of diseases can be screened. The genetic techniques have been gradually used for neonatal genetic disease screening in recent years. Gene detection technology includes quantitative PCR (qPCR) and high-throughput sequencing. High-throughput sequencing includes gene panel sequencing, whole-exome sequencing and whole-genome sequencing. At present, qPCR and gene panel sequencing are the main technologies to be used for newborn genetic disease screening. Genetic screening diseases range from single disease such as hearing loss, spinal muscular atrophy and severe combined immunodeficiency to multiple diseases. Besides standards and guidelines for the interpretation of sequence variants proposed by the American College of Medical Genetics and Genomics and the Association for Molecular Pathology in 2015, the interpretation of genetic screening results should also consider biochemical results and other results. The development of newborn genetic screening needs to follow ethical principles, including the ethics of newborn genetic screening as a public health project, the privacy ethics of newborns and their family members, and the ethics of bioinformatics. The development of newborn genetic screening will enable more patients with inherited diseases to receive early diagnosis and treatment and improve their prognosis, which is a milestone in the field of neonatal screening.

Genetic Variant c.245A>G (p.Asn82Ser) in GIPC3 Gene Is a Frequent Cause of Hereditary Nonsyndromic Sensorineural Hearing Loss in Chuvash Population

Hereditary nonsyndromic sensorineural hearing loss is a disease in which hearing loss occurs due to damage to the organ of the inner ear, the auditory nerve, or the center in the brain that is responsible for the perception of sound, characterized by wide locus and allelic heterogeneity and different types of inheritance. Given the diversity of population of the Russian Federation, it seems necessary to study the ethnic characteristics of the molecular causes of the disease. The aim is to study the molecular and genetic causes of hereditary sensorineural hearing loss in Chuvash, the fifth largest ethnic group in Russia. DNA samples of 26 patients from 21 unrelated Chuvash families from the Republic of Chuvashia, in whom the diagnosis of hereditary sensorineural hearing loss had been established, were analyzed using a combination of targeted Sanger sequencing, multiplex ligase-dependent probe amplification, and whole exome sequencing. The homozygous variant NM_133261.3(GIPC3):c.245A>G (p.Asn82Ser) is the major molecular cause of hereditary sensorineural hearing loss in 23% of Chuvash patients (OMIM #601869). Its frequency was 25% in patients and 1.1% in healthy Chuvash population. Genotyping of the NM_133261.3(GIPC3):c.245A>G (p.Asn82Ser) variant in five neighboring populations from the Volga-Ural region (Russian, Udmurt, Mary, Tatar, Bushkir) found no evidence that this variant is common in those populations.