Auditory and communicative abilities in the auditory neuropathy spectrum disorder and mutation in the Otoferlin gene: clinical cases study

The natural history, clinical outcomes, and genotype-phenotype relationship of otoferlin-related hearing loss: a systematic, quantitative literature review

Congenital hearing loss affects one in 500 newborns. Sequence variations in OTOF, which encodes the calcium-binding protein otoferlin, are responsible for 1-8% of congenital, nonsyndromic hearing loss and are the leading cause of auditory neuropathy spectrum disorders. The natural history of otoferlin-related hearing loss, the relationship between OTOF genotype and hearing loss phenotype, and the outcomes of clinical practices in patients with this genetic disorder are incompletely understood because most analyses have reported on small numbers of cases with homogeneous OTOF genotypes. Here, we present the first systematic, quantitative literature review of otoferlin-related hearing loss, which analyzes patient-specific data from 422 individuals across 61 publications. While most patients display a typical phenotype of severe-to-profound hearing loss with prelingual onset, 10-15% of patients display atypical phenotypes, including mild-to-moderate, progressive, and temperature-sensitive hearing loss. Patients' phenotypic presentations appear to depend on their specific genotypes. For example, non-truncating variants located in and immediately downstream of the C2E calcium-binding domain are more likely to produce atypical phenotypes. Additionally, the prevalence of certain sequence variants and their associated phenotypes varies between populations due to evolutionary founder effects. Our analyses also suggest otoacoustic emissions are less common in older patients and those with two truncating OTOF variants. Critically, our review has implications for the application and limitations of clinical practices, including newborn hearing screenings, hearing aid trials, cochlear implants, and upcoming gene therapy clinical trials. We conclude by discussing the limitations of available research and recommendations for future studies on this genetic cause of hearing loss.

Monitoring the Hearing Handicap and the Recognition Threshold of Sentences of a Patient with Unilateral Auditory Neuropathy Spectrum Disorder with Use of a Hearing Aid

Introduction Treatment for auditory neuropathy spectrum disorder (ANSD) is not yet well established, including the use of hearing aids (HAs). Not all patients diagnosed with ASND have access to HAs, and in some cases HAs are even contraindicated.

Objective To monitor the hearing handicap and the recognition threshold of sentences in silence and in noise in a patient with ASND using an HA.

Resumed Report A 47-year-old woman reported moderate sensorineural hearing loss in the right ear and high-frequency loss of 4 kHz in the left ear, with bilateral otoacoustic emissions. Auditory brainstem response suggested changes in the functioning of the auditory pathway (up to the inferior colliculus) on the right. An HA was indicated on the right. The patient was tested within a 3-month period before the HA fitting with respect to recognition threshold of sentences in quiet and in noise and for handicap determination. After HA use, she showed a 2.1-dB improvement in the recognition threshold of sentences in silence, a 6.0-dB improvement for recognition threshold of sentences in noise, and a rapid improvement of the signal-to-noise ratio from +3.66 to −2.4 dB when compared with the same tests before the fitting of the HA.

Conclusion There was a reduction of the auditory handicap, although speech perception continued to be severely limited. There was a significant improvement of the recognition threshold of sentences in silence and in noise and of the signal-to-noise ratio after 3 months of HA use.