Prelingual non-syndromic genetic deafness

Prelingual non-syndromic genetic deafness (also known as prelingual non-syndromic hereditary deafness or prelingual non-syndromic sensorineural hearing loss) refers to genetically caused hearing loss that is present before the development of speech (typically before age 2-3 years) and occurs without other associated clinical features affecting other organ systems. This condition specifically affects the auditory system, involving the inner ear (cochlea) or the auditory nerve, leading to sensorineural hearing loss that ranges from mild to profound. Because the hearing loss occurs before language acquisition, it can significantly impact speech and language development if not identified and managed early. Prelingual non-syndromic genetic deafness is genetically heterogeneous, meaning it can be caused by pathogenic variants in many different genes. The most common cause is mutations in the GJB2 gene (encoding connexin 26), which accounts for a substantial proportion of autosomal recessive cases. Other frequently implicated genes include SLC26A4, MYO15A, OTOF, TMC1, and many others. Over 100 genetic loci have been identified, designated as DFNB (autosomal recessive), DFNA (autosomal dominant), or DFNX (X-linked). Autosomal recessive inheritance is the most common pattern, accounting for approximately 75-80% of cases, while autosomal dominant forms account for roughly 15-20%, with X-linked and mitochondrial inheritance being less frequent. Newborn hearing screening programs have greatly improved early detection of this condition. Management depends on the degree of hearing loss and may include hearing aids for mild to moderate cases and cochlear implantation for severe to profound hearing loss, which has shown excellent outcomes particularly when performed early in life. Speech therapy and educational support are essential components of care. Genetic testing, including targeted gene panels or whole exome sequencing, plays an increasingly important role in confirming the diagnosis, guiding prognosis, and informing family counseling. Currently, there are no approved gene therapies, although research in this area is actively progressing.

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