Non-Syndromic Hearing Impairment in India: High Allelic Heterogeneity among Mutations in TMPRSS3, TMC1, USHIC, CDH23 and TMIE

Mutations in the autosomal genes TMPRSS3, TMC1, USHIC, CDH23 and TMIE are known to cause hereditary hearing loss. To study the contribution of these genes to autosomal recessive, non-syndromic hearing loss (ARNSHL) in India, we examined 374 families with the disorder to identify potential mutations. We found four mutations in TMPRSS3, eight in TMC1, ten in USHIC, eight in CDH23 and three in TMIE. Of the 33 potentially pathogenic variants identified in these genes, 23 were new and the remaining have been previously reported. Collectively, mutations in these five genes contribute to about one-tenth of ARNSHL among the families examined. New mutations detected in this study extend the allelic heterogeneity of the genes and provide several additional variants for structure-function correlation studies. These findings have implications for early DNA-based detection of deafness and genetic counseling of affected families in the Indian subcontinent.

Motor skill deficits in children with partial hearing

AIM:
We examined the effect of partial hearing, including cochlear implantation, on the development of motor skills in children (aged 6-12y).

METHOD:
Three independent groups of children were selected: a partial hearing group (n=25 [14 males, 11 females]; mean age 8y 8mo, SD 1y 10mo), a nonverbal IQ-matched group (n=27 [15 males, 12 females]; mean age 9y, SD 1y 6mo), and an age-matched group (n=26 [8 males, 18 females]; mean age 8y 8mo, SD 1y 7mo) from three schools with special units for children with partial hearing. All children with partial hearing had a bilateral hearing loss >60 decibels. Motor and balance skills were assessed using the Movement Assessment Battery for Children (MABC) and two protocols from the NeuroCom Balance Master clinical procedures.

RESULTS:
The mean standardized total MABC score of the children with partial hearing (95% confidence interval [CI] 71.8-88.7) was significantly lower than both the age-matched (95% CI 95.8-111.4; p<0.01) and the IQ-matched (95% CI 87.6-103.0; p=0.03) comparison groups. The children with partial hearing had particular difficulties with balance, most notably during tests of intersensory demand. However, subgroup analyses revealed that the effect of cochlear implantation was clearly dependent on the nature of the task.

INTERPRETATION:
Children with partial hearing are at high risk of clinical levels of motor deficit, with balance difficulties providing support for conventional vestibular deficit theory. However, the effect of cochlear implantation suggests that other sensory systems may be involved. A broader ecological perspective, which takes into account factors external to the child, may prove a useful framework for future research.

Developing a set of materials to teach hearing children about hearing impairment

This paper contains a set of materials to help hearing persons understand hearing loss.

A technique to train auditory and visual memory for speech patterns in young hearing-impaired children

This paper details a technique for training auditory memory for length of speech sounds in preschool children with a profound hearing loss.

Noise levels and hearing conservation in a water treatment facility

This paper describes a study assessing the sound levels and noise exposures of a municipal water treatment plant to determine the level of employee noise exposure dosages and to make any necessary recommendations regarding reducing the risk of noise induced hearing loss in employees.

Hearing hazards to firefighters

This paper examines the risks of occupational noise induced hearing loss in firefighters. OSHA and National Institute for Occupational Safety and Health (NIOSH) guidelines are described and noise data collected from the Blue Island (Illinois) Fire Department is analyzed.

A comparison of three hearing aid manufacturers' recommended first fit to two generic prescriptive targets with the pediatric population

The purpose of this study is to compare three hearing aid manufacturers' recommended "First Fit" to the generic recommended fittings by DSL i/o and NAL-NL1 for a 12 month old child with varying degrees of sensorineural hearing loss.

Effectiveness of visual feedback provided by an electromagnetic articulograph (EMA) system: training vowel production in individuals with hearing impairment

An electromagnetic articulograph (EMA) system was used to provide a participant with congenital hearing loss visual biofeedback information on speech production. Five normally hearing listeners reported a change in their perception of the speech sound /æ/ in the various conditions of the study.

The role of siblings in the habilitation of families with children who are deaf or hard-of-hearing

Siblings play a vital role in the health of a family as they adjust to having a child who is deaf or hard-of-hearing. In this project, a series of workshops has been designed for the siblings of children with a hearing loss to help better understand hearing loss and foster healthy sibling relationships.

Utilizing hearing assistive technology (HAT) to assess speech recognition: Comparison of word recognition scores obtained by hearing instrument users

The ability for individuals with hearing loss to accurately recognize correct versus incorrect verbal responses during traditional word recognition testing across four different listening conditions was assessed.

Educating deaf and hard of hearing students in the mainstream classroom

This paper examines the mainstreaming of hearing-impaired students in regular education classrooms. It evaluates the areas where teachers need more information regarding deafness, hearing loss and the teaching of hearing-impaired students. The paper also presents a list of resources to assist teachers in the education of hearing-impaired students in the mainstream classroom.

Opportunistic assessment of hearing in elderly inpatients

Objective: To determine the prevalence of occult hearing loss in elderly inpatients, to evaluate feasibility of opportunistic hearing screening and to determine subsequent provision of hearing aids. Materials and methods: Subjects (>65 years) were recruited from five elderly care wards. Hearing loss was detected by a ward-based hearing screen comprising patient-reported assessment of hearing disability and a whisper test. Subjects failing the whisper test or reporting hearing difficulties were offered formal audiological assessment. Results: Screening was performed on 51 patients aged between 70 and 95 years. Of the patients, 21 (41%) reported hearing loss and 16 (31%) failed the whisper test. A total of 37 patients (73%) were referred for audiological assessment with 17 (33%) found to have aidable hearing loss and 11 were fitted with hearing aids (22%). Discussion: This study highlights the high prevalence of occult hearing loss in elderly inpatients. Easy two-step screening can accurately identify patients with undiagnosed deafness resulting in significant proportions receiving hearing aids.

The relation between speech recognition in noise and the speech-evoked brainstem response in normal-hearing and hearing-impaired individuals

Little is known about the way speech in noise is processed along the auditory pathway. The purpose of this study was to evaluate the relation between listening in noise using the R-Space system and the neurophysiologic response of the speech-evoked auditory brainstem when recorded in quiet and noise in adult participants with mild to moderate hearing loss and normal hearing.

Emotion perception and talker discrimination in pediatric hearing aid users

The primary goal of this study is to examine the ability of pediatric hearing-aid listeners, with mild to moderately-severe hearing loss, to perceive emotion and to discriminate talkers. These listeners’ performance is compared to that of similarly-aged listeners with normal hearing and who use cochlear implants.

Unexpected genetic heterogeneity in a large consanguineous Brazilian pedigree presenting deafness

Nonsyndromic autosomal recessive deafness accounts for 80% of hereditary deafness. To date, 52 loci responsible for autosomal recessive deafness have been mapped and 24 genes identified. Here, we report a large inbred Brazilian pedigree with 26 subjects affected by prelingual deafness. Given the extensive consanguinity found in this pedigree, the most probable pattern of inheritance is autosomal recessive. However, our linkage and mutational analysis revealed, instead of an expected homozygous mutation in a single gene, two different mutant alleles and a possible third undetected mutant allele in the MYO15A gene (DFNB3 locus), as well as evidence for other causes for deafness in the same pedigree. Among the 26 affected subjects, 15 were homozygous for the novel c.10573delA mutation in the MYO15A gene, 5 were compound heterozygous for the mutation c.10573delA and the novel deletion c.9957_9960delTGAC and one inherited only a single c.10573delA mutant allele, while the other one could not be identified. Given the extensive consanguinity of the pedigree, there might be at least one more deafness locus segregating to explain the condition in some of the subjects whose deafness is not clearly associated with MYO15A mutations, although overlooked environmental causes could not be ruled out. Our findings illustrate a high level of etiological heterogeneity for deafness in the family and highlight some of the pitfalls of genetic analysis of large genes in extended pedigrees, when homozygosity for a single mutant allele is expected.