Newborn screening for common genetic variants associated with permanent hearing loss: Implementation in Ontario and a review of the first 3 years.

Purpose: Universal newborn hearing screening (UNHS) programs using audiometric techniques alone are limited in ability to detect non-congenital childhood permanent hearing loss (PHL). In 2019, Ontario launched universal newborn screening (NBS) for PHL risk factors: congenital cytomegalovirus (cCMV) and 22 common variants in GJB2 and SLC26A4. Here we describe our experience with genetic risk factor screening.

Methods: Ontario newborns who participated in UNHS were offered risk factor screening on dried blood spots collected for conventional newborn screening. Screening was conducted by custom MassArray assay and positives confirmed by Sanger sequencing or PCR. Diagnostic audiology assessment was performed for all screen positive infants.

Results: 412,424 infants were screened, 93 had two variants in GJB2 or SLC26A4. Of these, 72 had confirmed PHL, 20 had normal hearing and 1 declined follow-up. Thirteen infants with PHL (1 in 31,724; 11.8% of screen positives) were not identified through audiometric testing as they passed (3) or missed (10) screening. Importantly, among infants who ultimately received cochlear implants, detection of the genetic etiology through NBS led to accelerated time to diagnosis, assessment, and intervention.

Conclusion: Genetic screening has strengthened UNHS and care for infants with or at risk for PHL in Ontario. This study is a step towards the broader inclusion of genomic testing in NBS.