Connexin 26 (GJB2 gene) mutations are the most common cause of autosomal recessive non-syndromic congenital sensorineural hearing loss (SNHL). Which pathophysiological mechanism best explains hearing loss in connexin-26 deficiency?

• A Degeneration of spiral ganglion neurons due to absent neurotrophin signaling
• B Malformation of the organ of Corti due to absent Wnt signaling
• C Impaired potassium recycling from hair cells back to the endolymph via supporting cells ✓
• D Defective prestin motor protein in outer hair cells

Explanation

Connexin 26 (encoded by GJB2) forms gap junctions in cochlear supporting cells that are critical for potassium (K+) recycling. After K+ enters hair cells during mechanotransduction, it must be returned to the endolymph via connexin gap junctions in the Deiters cells, pillar cells, and fibrocytes of the spiral ligament to maintain the endocochlear potential. Deficiency in connexin 26 disrupts this K+ circulation, leading to hair cell death and SNHL. Prestin defects cause a different type of SNHL (OHC electromotility loss).

Reference: Dhingra Diseases of Ear, Nose and Throat, 7th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.