Abstract: The STRC gene has been shown to be the second most common cause for congenital non-syndromic sensorineural hearing loss (SNHL) and exhibits as the most common mild to moderate SNHL group. This study aimed at confirming the prevalence, severity, and hearing stability of a cohort of children with STRC mutations. Additionally, genetic mutations within the STRC gene were categorized to determine if hearing loss progression occurred within a specific mutation.
Summary: Background The STRC gene has been shown to be the second most common cause for congenital non-syndromic sensorineural hearing loss (SNHL) and exhibits as the most common mild to moderate SNHL group. It encodes stereocilin which maintains the structure of stereocilia by linking their tips to one another. This study aimed at confirming the prevalence, severity, and hearing stability of a cohort of children with STRC mutations. Additionally, genetic mutations within the STRC gene were categorized to determine if hearing loss progression occurred within a specific mutation.
Hypotheses This data will show STRC is the most prevalent congenital non-syndromic hearing loss in the mild to moderate hearing loss range. Through audiologic evaluations, progression has been documented; therefore, we hypothesize that STRC is not statistically “stable” as suggested in other literature.
Methods A retrospective chart review (2014 to 2023) inclusive of genetic and audiologic data was conducted at an academic children’s hospital. Audiologic data were reviewed to determine degree and stability in the cohort. The criterion for progression includes a decrease in PTA of 10 dB or more for either ear, a 10 dB or more decrease in hearing threshold at 2 adjacent frequencies in the test ear, or a 15 dB or more decrease in hearing threshold at one or more frequencies in the test ear. We analyzed this data by participants and by ears.
Results A total 354 subjects underwent genetic testing and 180 (50.8%) were positive. STRC mutations was the second largest group in terms of prevalence of mutations (30/180; 16.7%) as well the mild/ moderate SNHL group (23/91, 25.3%). Twelve of 27 subjects were found to have progression (8 bilateral, 4 unilateral; 20/54 ears) with a median progression of 1.3 dB per year (Interquartile Range: 0.7 dB, 3.3 dB).
Conclusions Our STRC cohort constitutes the second largest congenital non-syndromic SNHL subgroup in terms of prevalence and having mild to moderate SNHL, secondary to GJB2. Contrary to published reports, hearing progression is known to occur in this gene, and in two children in this study, it was significant enough to necessitate cochlear implantation. No correlation between specific types of mutation and hearing progression was found. Associated deafness-infertility syndrome found in 12 males was a challenge for our genetic counselor.
Brief Summary of Clinical Takeaways: Within this cohort, the hypothesis that STRC is the most prevalent congenital non-syndromic hearing loss in the mild to moderate hearing loss range was disproven. The hypothesis that hearing thresholds progressed was supported. No correlation between specific types of mutation and hearing progression was found. Results provide information for counseling.
Assumptions Attendees should have basic knowledge about genetics including what it means to have an autosomal dominant or autosomal recessive gene.
Learning Objectives:
Upon completion, participants will be able to identify genes responsible for congenital, non-syndrome sensorineural hearing loss.
Upon completion, participants will be able to describe audiologic characteristics of children identified with STRC gene mutation.
Upon completion, participants will be able to utilize this data to better inform parents/caregivers of hearing loss progression in children with STRC mutation/s.
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