Imputation of SNPs associated with presbycusis through linkage disequilibrium analysis in the ILDR1 gene.

The single-nucleotide polymorphisms (SNP) ILDR1 rs2332035 has shown a high statistical association with presbycusis (hearing loss with age or age-related hearing impairment (ARHI)), according to genetic association studies in European populations. However, linked markers have not been surveyed. Here linkage disequilibrium (LD) of markers in ILDR1, in relation to rs2332035, is explored in the 2504 individuals from the 1000Genomes database. Of the 920 SNPs retrieved, 10 showed strong LD (r2= 0.8) in Europeans and Latin Americans, which are proposed here as candidate markers for both control-case association and cause-effect studies in both populations.

Role of melatonin in prevention of age-related hearing loss.

INTRODUCTION: Age-related hearing loss (ARHL) is a consequence of aging of the auditory system. The best known mechanism of cell death in ARHL is apoptosis due to increased production of reactive oxygen species. In this context, it is hypothesized that melatonin, owing to its high antioxidant potential and its action in the mitochondria, helps prevent or delay outer hair cell dysfunction (HCD). AIMS: To evaluate the effect of melatonin on the prevention of HCD dysfunction in the ARHL process in a susceptible murine C57BL/6J model. METHOD: C57BL/6J animals were divided into two groups: control (CG) and melatonin (MG). The CG received a saline and ethanol solution and the MG, melatonin (10 mg/kg/day). The solutions were offered daily (50 µl) orally over a 10-month period. Distortion Product Otoacoustic Emissions (DPOAE) measurements were conducted once a month. RESULTS: There was a decrease in DPOAE values in both groups over time and a differentiation between them from the 10th month of life onwards. At 10 months, the MG maintained higher DPOAE values than the CG at all frequencies tested. CONCLUSION: The use of melatonin has otoprotective effects on HCD in the ARHL process in the C57BL/6J model.

Genetic and audiologic study in elderly with sensorineural hearing loss.

PURPOSE: This study aimed to correlate probable predisposing factors for sensorineural hearing loss in elderly by investigating the audiologic characteristics and frequency of mutations in genes considered responsible for non-syndromic hearing loss. METHODS: Sixty elderly patients were separated into two groups: the Case Group, composed of 30 individuals, 21 females and nine males, all 60 years old or older and presenting diagnoses of sensorineural hearing loss, and the Control Group, composed of 30 elderly individuals matched to the experimental group by age and gender, presenting normal hearing. The patients underwent anamnesis and pure tone audiometry in frequencies of 250, 500, 1000, 2000, 3000, 4000 and 6000 Hz. Blood samples were collected from each patient for analysis of mutations in nuclear and mitochondrial genes related to non-syndromic sensorineural hearing loss. RESULTS: It was observed a greater tendency to noise exposure and consumption of alcohol in the Case Group. The statistically significant symptoms between the groups were tinnitus and hearing difficulty in several situations as: silent environment, telephone, television, sound location and in church. All the individuals of Case Group presented sensorineural and bilateral hearing loss. The symmetry and progression of the hearing impairment were also statistically significant between the groups. No genetic mutations were identified. CONCLUSION: The most reported symptoms were communication difficulties and tinnitus. The predominant auditory characteristics included sensorineural, bilateral, progressive and symmetrical hearing loss. It was not evidenced a relationship between sensorineural hearing loss in elderly and genes considered responsible for non-syndromic hearing loss as no genetic mutation was found in this study.

Genetic and audiologic study in elderly with sensorineural hearing loss / Estudo genético e audiológico em idosos com perda auditiva sensorioneural

PURPOSE: This study aimed to correlate probable predisposing factors for sensorineural hearing loss in elderly by investigating the audiologic characteristics and frequency of mutations in genes considered responsible for non-syndromic hearing loss. METHODS: Sixty elderly patients were separated into two groups: the Case Group, composed of 30 individuals, 21 females and nine males, all 60 years old or older and presenting diagnoses of sensorineural hearing loss, and the Control Group, composed of 30 elderly individuals matched to the experimental group by age and gender, presenting normal hearing. The patients underwent anamnesis and pure tone audiometry in frequencies of 250, 500, 1000, 2000, 3000, 4000 and 6000 Hz. Blood samples were collected from each patient for analysis of mutations in nuclear and mitochondrial genes related to non-syndromic sensorineural hearing loss. RESULTS: It was observed a greater tendency to noise exposure and consumption of alcohol in the Case Group. The statistically significant symptoms between the groups were tinnitus and hearing difficulty in several situations as: silent environment, telephone, television, sound location and in church. All the individuals of Case Group presented sensorineural and bilateral hearing loss. The symmetry and progression of the hearing impairment were also statistically significant between the groups. No genetic mutations were identified. CONCLUSION: The most reported symptoms were communication difficulties and tinnitus. The predominant auditory characteristics included sensorineural, bilateral, progressive and symmetrical hearing loss. It was not evidenced a relationship between sensorineural hearing loss in elderly and genes considered responsible for non-syndromic hearing loss as no genetic mutation was found in this study.

OBJETIVO: Este estudo teve como objetivo correlacionar prováveis fatores predisponentes para a perda auditiva sensorioneural em idosos, investigando as características audiológicas e a frequência de mutações em genes considerados responsáveis por perda auditiva não-sindrômica. MÉTODOS: Sessenta idosos foram separados em dois grupos: Grupo de Caso, composto por 30 indivíduos, 21 do gênero feminino e nove do gênero masculino, com 60 anos ou mais, apresentando diagnóstico de perda auditiva sensorioneural, e o Grupo Controle, composto por 30 idosos pareados com o grupo experimental por idade e gênero, apresentando audição normal. Os pacientes foram submetidos à anamnese e audiometria tonal liminar nas frequências de 250, 500, 1000, 2000, 3000, 4000 e 6000 Hz. Amostras de sangue foram coletadas de cada paciente para análise de mutações em genes nucleares e mitocondriais relacionados à perda auditiva sensorioneural não sindrômica. RESULTADOS: Houve uma maior tendência à exposição a ruído e consumo de bebidas alcoólicas no Grupo de Caso. Os sintomas estatisticamente significativos entre os grupos foram zumbido e dificuldade para ouvir em diversas situações como: ambiente silencioso, telefone, televisão, localização sonora e na igreja. Todos os indivíduos do Grupo de Caso apresentaram perda auditiva sensorioneural bilateral. A simetria e progressão da deficiência auditiva também foram estatisticamente significativas entre os grupos. Não foram identificadas mutações genéticas. CONCLUSÃO: Os sintomas mais relatados foram zumbido e dificuldades de comunicação. As características audiológicas predominantes foram perda auditiva sensorioneural, bilateral, simétrica e progressiva. Não foi evidenciada relação entre perda auditiva sensorioneural em idosos e genes considerados responsáveis por perda auditiva não sindrômica, pois não foram encontradas mutações genéticas neste estudo.

Tracking of the genetic deafness associated to the aging in Brazilian patients.

INTRODUCTION: Presbyacusis is the most common cause of auditory dysfunction that is generally associated with aging in industrialized societies. OBJECTIVE: To assess the presence of the mitochondrial 4977-bp deletion in Brazilian patients with presbyacusis. MATERIALS AND METHODS: One hundred unrelated patients of both genders were clinically examined to exclude syndromic forms of deafness. Specific oligonucleotide primers were designed to amplify the cytochrome b gene and the 4977-bp deletion of the mtDNA using the polymerase chain reaction. RESULTS: The mtDNA(4977) deletion was not identified in any of the samples analyzed. A region of the cytochrome b gene has been previously amplified and the presence of the mtDNA and the non-deleted mtDNA was confirmed in all of the samples. CONCLUSIONS: These molecular findings disagree with reports describing the mtDNA(4977) deletion associated with aging, but do not discard the possibility of the existence of mutations in other genes in the patients and, highlight the importance of identifying the underlying genetic causes of presbyacusis, in the Brazilian population, to provide a better understanding of the internal ear diseases.