Comprehensive Analysis and Genetic Insights Into GJB2 c.35delG Mutation-Associated Non-Syndromic Hearing Loss in Morocco.

Abstract

Objective: To assess the prevalence of the GJB2 c.35delG mutation among Moroccan patients with nonsyndromic sensorineural hearing loss (NSHL) and compare it with frequencies reported in other North African populations.

Study design: Retrospective cohort study.

Setting: Multidisciplinary tertiary care hearing loss genetics clinic.

Methods: A total of 304 unrelated Moroccan patients with prelingual bilateral (NSHL), recruited between May 2022 and June 2025, were included. Genomic Deoxyribonucleic Acid (DNA) was extracted from peripheral blood samples, and the c.35delG mutation was detected via PCR amplification and Sanger sequencing. Demographic and clinical data, including age at diagnosis, sex, and family history, were systematically collected.

Results: The c.35delG mutation contributed to 18% of (NSHL) cases in this cohort, with homozygosity being the most frequent genotype. The mutation was especially prevalent in patients from consanguineous families. Clinically, hearing loss was early-onset, bilateral, and mostly profound, demonstrating a strong genotype-phenotype correlation. The observed frequency aligns with regional data from other North African populations, reflecting a shared genetic background.

Conclusion: The c.35delG mutation is a major cause of (NSHL) in Morocco, though slightly less frequent than reported in previous national studies. These findings support incorporating GJB2 genetic screening into early diagnostics, genetic counseling, and targeted prevention programs, particularly in populations with high consanguinity rates.