Endothelin-1 gene polymorphism in sudden sensorineural hearing loss

Endothelial Dysfunction and Metabolic Disorders in Patients with Sudden Sensorineural Hearing Loss

Sudden sensorineural hearing loss (SSNHL) is defined as a sensorineural hearing loss of 30 dB or greater on at least three contiguous audiometric frequencies occurring within a 72 h period. Although SSNHL is commonly encountered in clinical audiology and otolaryngology practice, its etiopathogenesis continues to be poorly understood. Scientific investigations have highlighted the vulnerability of cochlear microcirculation to blood flow alterations. Even mild hypoperfusion can lead to immediate dysfunction in the organ of Corti, given the heightened susceptibility of cochlear hair cells to hypoxia and ischemic damage. The purpose of this review paper is to present evidence of endothelial and vascular involvement in SSNHL and the risk factors, such as metabolic syndrome, that may negatively impact the inner ear's vascular supply, influencing the onset pattern, incidence, and prognosis of SSNHL. By addressing these variables, we can deepen our comprehension of the mechanisms underlying SSNHL and potentially uncover strategies for prevention.

D-Galactose and Hypoxia Induce the Early Onset of Age-Related Hearing Loss Deterioration in a Mouse Model

BACKGROUND

We previously showed that aging accelerates after 3 months of exposure to hypoxia and environmental change but not genetic modifications. Here, we aimed to simply induce early-onset age-related hearing loss within a short period based on our previous method.

METHODS

We randomly divided 16 C57BL/6 mice into four groups that were maintained under conditions of normoxia and hypoxia with or without injected D-galactose for 2 months. Deteriorated hearing, the expression of age-related factors, and oxidative stress responses were detected using the click and tone burst auditory brainstem response test, reverse transcription-polymerase chain reaction, and by measuring superoxide dismutase (SOD).

RESULTS

The group maintained under hypoxia combined with D-galactose lost hearing particularly at 24 Hz and 32 Hz at 6 weeks compared with the other groups. Aging-related factors were also significantly decreased in the hypoxia and D-galactose groups. However, SOD levels did not significantly differ among the groups.

CONCLUSION

Age-related hearing loss is an environmental disorder induced by chronic oxidative stress associated with genetic backgrounds. Our findings suggested that D-galactose and hypoxia can induce the phenotypes of age-related hearing loss and aging-associated molecules in a murine model within a short time with environmental stimulation alone.

Deafness gene screening based on a multilevel cascaded BPNN model

Sudden sensorineural hearing loss is a common and frequently occurring condition in otolaryngology. Existing studies have shown that sudden sensorineural hearing loss is closely associated with mutations in genes for inherited deafness. To identify these genes associated with deafness, researchers have mostly used biological experiments, which are accurate but time-consuming and laborious. In this paper, we proposed a computational method based on machine learning to predict deafness-associated genes. The model is based on several basic backpropagation neural networks (BPNNs), which were cascaded as multiple-level BPNN models. The cascaded BPNN model showed a stronger ability for screening deafness-associated genes than the conventional BPNN. A total of 211 of 214 deafness-associated genes from the deafness variant database (DVD v9.0) were used as positive data, and 2110 genes extracted from chromosomes were used as negative data to train our model. The test achieved a mean AUC higher than 0.98. Furthermore, to illustrate the predictive performance of the model for suspected deafness-associated genes, we analyzed the remaining 17,711 genes in the human genome and screened the 20 genes with the highest scores as highly suspected deafness-associated genes. Among these 20 predicted genes, three genes were mentioned as deafness-associated genes in the literature. The analysis showed that our approach has the potential to screen out highly suspected deafness-associated genes from a large number of genes, and our predictions could be valuable for future research and discovery of deafness-associated genes.

Transcriptomic analysis and ednrb expression in cochlear intermediate cells reveal developmental differences between inner ear and skin melanocytes

In the inner ear, the neural crest gives rise to the glia of the VIII ganglion and two types of melanocytic cells: The pigmented cells of the vestibular system and intermediate cells of the stria vascularis. We analyzed the transcriptome of neonatal intermediate cells in an effort to better understand the development of the stria vascularis. We found that the expression of endothelin receptor B, which is essential for melanocyte development, persists in intermediate cells long after birth. In contrast, skin melanocytes rapidly downregulate the expression of EdnrB. Our findings suggest that endothelins might have co‐opted new functions in the inner ear during evolution of the auditory organ.

Genetic Polymorphisms in Sudden Sensorineural Hearing Loss: An Update

OBJECTIVE

To investigate the association between genetic polymorphisms and sudden sensorineural hearing loss (SSNHL). Most of the SSNHL cases still remain idiopathic, and several etiopathogenetic hypotheses, including a genetic predisposition, have been proposed.

METHODS

A literature review was conducted using different databases: Medline/PubMed, EMBASE, and CINAHL, according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. All databases have been searched from May 2016 to April 2020.

RESULTS

Genetic susceptibility could represent a key element in the pathogenesis of SSNHL. A number of genetic polymorphisms related to (1) inner ear microvascular disease and endothelial dysfunction and (2) to inner ear oxidative stress and inflammation have been addressed in the current literature.

CONCLUSIONS

The potential identification of a genetic profile related to SSNHL could provide a more accurate prognostic evidence of idiopathic SSNHL (ISSNHL), offering to the patients not only early-prevention strategies but eventually information on various inheritance modalities.

Genetic Polymorphisms and Susceptibility to Sudden Sensorineural Hearing Loss: A Systematic Review

BACKGROUND

Recently, genetic factors have been considered as an important risk factor for sudden sensorineural hearing loss (SSNHL). Many studies analyzed the association between SSNHL and polymorphisms. However, most of them gave inconclusive results. Key Message: We performed a systematic review to find out the association between polymorphisms and susceptibility to SSNHL. Finally, 47 studies involving 5,230 SSNHL patients and 68 genes were included for analysis and discussion of results. Polymorphisms in 26 genes have been suggested to be correlated with the susceptibility to SSNHL.

SUMMARY

Although a great number of studies support that polymorphisms in genes are associated with susceptibility to SSNHL, we need large multicenter studies, which evaluate multiple single nucleotide polymorphisms in SSNHL patients, to find real genetic risk factors for susceptibility to SSNHL. This is very helpful in designing more effective prevention and treatment strategies for patients with SSNHL.

MTHFR AND ApoE genetic variants association with sudden sensorineural hearing loss

HYPOTHESIS

Although the pathogenesis of sudden sensorineural hearing loss (SSNHL) is not clear, however several causes including genetic factors seems to be implicated. We hypothesized that common genetic variants might be involved in SSNHL.

BACKGROUND

SSNHL is known to be an idiopathic disease because the causative factors have not been identified. Several causes including genetic and viral infection besides immune system reaction, neurological disorders, medications, etc. have been previously reported. We examined the association between ApoE and MTHFR gene variants in SSNHL.

METHODS

This study includes case-control scheme encompassing a total of 177 individuals, include patients inflicted with SSNHL and healthy subjects as control group. Genotyping of MTHFR and ApoE variants was conducted by PCR - RFLP method.

RESULT

Our study showed that MTHFR rs1801133 allele frequency is significantly different between cases and controls. Also genotype distribution of ApoE was significantly different between patients and healthy controls.

CONCLUSIONS

MTHFR C677T and ApoE gene variant may be associated with sudden sensorineural hearing loss in an Iranian population.

eNOS gene Glu298Asp variant confer risk in sudden sensorineural hearing loss

BACKGROUND

Sudden sensorineural hearing loss (SSNHL) causes the loss of hearing of 30 dB or greater on at least three contiguous frequencies. It is known to be a multifactorial disease which the exact cause is unknown, rendering it as an idiopathic disorder of patients.

AIMS/OBJECTIVES

This study aims to shed further light on pathogenesis of this disease by studying the association between eNOS gene Glu298Asp polymorphism and VDR gene FokI polymorphism with SSNHL in Iranian population.

MATERIAL AND METHODS

This study involves a total of 77 cases and 100 controls, with patients inflicted with SSNHL categorized in case group and healthy subjects as control group. Genotyping of the VDR and eNOS genes was conducted by the polymerase chain reaction and restriction fragment length polymorphism (PCR-RFLP) method.

RESULTS

Our results showed a statistically significant association between genotype frequencies of eNOS gene Glu298Asp polymorphism in case group compared to healthy individuals in the control group (p = .01). Also, TT genotype was significantly the most prevalent genotype in case group in comparison to control group (TT vs GT + GG, OR = 3.5; 95% CI = 1.18-11.79). On the other hand, analysis of VDR gene FokI polymorphism frequencies showed no statistically significant association with SSNHL.

CONCLUSIONS AND SIGNIFICANCE

Our findings showed a significant association between the eNOS gene Glu298Asp polymorphism and SSNHL in the Iranian population; and "TT" genotype might be considered as a risk factor for SSNHL.

Sudden sensorineural hearing loss and polymorphisms in iron homeostasis genes: new insights from a case-control study

Background. Even if various pathophysiological events have been proposed as explanations, the putative cause of sudden hearing loss remains unclear. Objectives. To investigate and to reveal associations (if any) between the main iron-related gene variants and idiopathic sudden sensorineural hearing loss. Study Design. Case-control study. Materials and Methods. A total of 200 sudden sensorineural hearing loss patients (median age 63.65 years; range 10-92) were compared with 400 healthy control subjects. The following genetic variants were investigated: the polymorphism c.-8CG in the promoter of the ferroportin gene (FPN1; SLC40A1), the two isoforms C1 and C2 (p.P570S) of the transferrin protein (TF), the amino acidic substitutions p.H63D and p.C282Y in the hereditary hemochromatosis protein (HFE), and the polymorphism c.-582AG in the promoter of the HEPC gene, which encodes the protein hepcidin (HAMP). Results. The homozygous genotype c.-8GG of the SLC40A1 gene revealed an OR for ISSNHL risk of 4.27 (CI 95%, 2.65-6.89; P = 0.001), being overrepresented among cases. Conclusions. Our study indicates that the homozygous genotype FPN1 -8GG was significantly associated with increased risk of developing sudden hearing loss. These findings suggest new research should be conducted in the field of iron homeostasis in the inner ear.