CACNA1D and hearing loss disorder: Pathologic mutations in CABP2 lead to moderate-to-severe autosomal recessive nonsyndromic hearing loss, DFNB93.27, 267 DFNB93 hearing impairment may result from an enhanced steady-state inactivation of CaV1.3 channels at the IHC synapse, limiting their availability to trigger synaptic transmission, resulting in elevated auditory thresholds.268