Nonsyndromic Hearing Loss and Deafness, DFNB1

Hearing loss is the most common sensory defect, affecting one to three out of every 1,000 newborns, with half of the cases attributable to genetic factors. Autosomal recessive nonsyndromic deafness or DFNB1 ("Nonsyndromic hearing loss and deafness") affects 70% of neonates with congenital hereditary hearing deficiency and is characterized by total or partial hearing loss.

More than 90 genes have been identified, most of which are involved in the development and function of the inner ear, whose alteration is related to some type of deafness, both syndromic and nonsyndromic, or both at the same time. However, in the Caucasian population, mutations in the GJB2 gene, which encodes connexin 26, are responsible for 60% of autosomal recessive nonsyndromic sensorineural hearing loss cases worldwide.

DFNB1 nonsyndromic hearing loss and deafness is present from birth and is not progressive, meaning it does not worsen over time. The degree of deafness varies greatly among individuals, even among affected members of the same family, and is classified into four phenotypic categories: mild, moderate, severe, and profound. Studies indicate that the severity depends on the effect that mutations present in the patients have on the connexin 26 protein.

Use of hearing aids; enrollment in appropriate educational programs; consider the option of surgery (cochlear implantation) to improve hearing in individuals with profound deafness. However, these devices, which aim to simulate the functioning of the inner ear, do not restore normal hearing.