Genetic and audiological determinants of hearing loss in high-risk neonates.

Abstract

Objective: We aimed to investigate the correlation between prevalent risk factors for high-risk neonates in neonatal intensive care unit and their hearing loss, and to examine the audiological features and genetic profiles associated with different deafness mutations in our tertiary referral center. This research seeks to deepen our understanding of the etiology behind congenital hearing loss.

Methods: We conducted initial hearing screenings, including automated auditory brainstem response, distortion product otoacoustic emission, and acoustic immittance on 443 high-risk neonates within 7 days after birth and 42 days (if necessary) after birth. Neonates who failed initial screenings underwent further diagnostic tests at 3 months. The risk factors were analyzed retrospectively by Chi-Square test and stepwise logistic regression. Genetic analysis involved a deafness sequencing panel targeting 19 pathogenic variants across four genes (GJB2, GJB3, SLC26A4, and MT-RNR), applied to both the study cohort and a larger hearing screening cohort of 14863 neonates from our center and different medical centers in the same region.

Results: Out of the 443 high-risk neonates, 222 failed their diagnostic hearing tests. Logistic regression identified preterm birth, neonatal hyperbilirubinemia and advanced maternal age (≧35 yr) as significant risk factors for hearing loss. Genetic screening of 33 neonates who failed the diagnostic tests revealed that 7 (21.21%) carried at least one pathogenic variant, with identified 1 homozygotes and 3 heterozygotes in the GJB2, 1 homozygotes and 1 heterozygotes in the SLC26A4 gene, and 1 homoplasmic variant in the MT-RNR (12SrRNA). In the larger hearing screening cohort, 497 (3.34%) were genetically positive for deafness mutations, among whom 29 had the diagnostic hearing tests and 7 eventually diagnosed with hearing loss. Of the rest 468 neonates who didn't have the diagnostic tests, 445 (95.09%) passed the hearing screening tests.

Conclusion: Preterm birth, neonatal hyperbilirubinemia and advanced maternal age are critical risk factors for hearing impairment in high-risk neonates. Mutations such as c.235delC in GJB2 and c.919-2A>G in SLC26A4 are the most common. Long-term follow-up of neonates carrying heterozygous variants, particularly in genes like GJB3, is necessary to understand their progression and hearing outcomes. This study highlights the importance of deafness gene screening in neonates to ensure accurate diagnosis and effective intervention.

Level of evidence: Level 3.