Peripheral vestibular system: Age-related vestibular loss and associated deficits

Given the interdependence of multiple factors in age-related vestibular loss (e.g., balance, vision,cognition), it is important to examine the individual contributions of these factors with ARVL. While therelationship between the vestibular and visual systems has been well studied (Bronstein et al., 2015),little is known about the association of the peripheral vestibular system with neurodegenerative disorders (Cronin et al., 2017). Further, emerging research developments implicate the vestibular system asan opportunity for examining brain function beyond balance, and into other areas, such as cognition andpsychological functioning. Additionally, the bidirectional impact of psychological functioning is understudied in ARVL. Recognition of ARVL as part of a multifaceted aging process will help guide thedevelopment of integrated interventions for patients who remain at risk for decline. In this review, wewill discuss a wide variety of characteristics of the peripheral vestibular system and ARVL, how it relatesto neurodegenerative diseases, and correlations between ARVL and balance, vision, cognitive, and psychological dysfunction. We also discuss clinical implications as well as future directions for research, withan emphasis on improving care for patients with ARVL.

The genetic basis of deafness in populations of African descent

Hearing loss is the most common sensorineural disorder worldwide and is associated with more than1000 mutations in more than 90 genes. While mutations in genes such as GJB2(gap-junction protein β 2)and GJB6(gap-junction protein β 6) are highly prevalent in Caucasian, Asian, and Middle Eastern populations, they are rare in both native African populations and those of African descent. The objective of this paper is to review the current knowledge regarding the epidemiology and genetics of hearing loss in African populations with a focus on native sub-Saharan African populations. Environmental etiologies related to poor access to healthcare and perinatal care account for the majority of cases. Syndromic etiologies including Waardenburg, Pendred and Usher syndromes are uncommon causes of hearing loss in these populations. Of the non-syndromic causes, common mutations in GJB2 and GJB6 are rarely implicated in populations of African descent. Recent use of next-generation sequencing(NGS) has identified several candidate deafness genes in African populations from Nigeria and South Africa that are unique when compared to common causative mutations worldwide. Researchers also recently described a dominant mutation in MYO3α in an African American family with non-syndromic hearing loss. The use of NGS and specialized panels will aid in identifying rare and novel mutations in a more cost-and timeeffective manner. The identification of common hearing loss mutations in indigenous African populations will pave the way for translation into genetic deafness research in populations of African descent worldwide.

Precision medicine in hearing loss

Precision medicine（PM） proposes customized medical care based on a patient＇s unique genome, biomarkers, environment and behaviors. Hearing loss（HL） is the most common sensorineural disorder worldwide and is frequently caused by a single genetic mutation. With recent advances in PM tools such as genetic sequencing and data analysis, the field of HL is ideally positioned to adopt the strategies of PM.Here, we review current and future applications of PM in HL as they relate to the four core qualities of PM（P4）： predictive, personalized, patient-centered, and participatory. We then introduce a strategy for effective incorporation of HL PM into the design of future research studies, electronic medical records,and clinical practice to improve diagnostics, prognostics, and, ultimately, individualized patient treatment. Finally, specific anticipated ethical and economic concerns in this growing era of genomics-based HL treatment are discussed. By integrating PM principles into translational HL research and clinical practice, hearing specialists are uniquely positioned to effectively treat the heterogeneous causes and manifestations of HL on an individualized basis.