POU3F4 and hearing loss disorder: Studies of the POU3F4 pathogenic variants have shown that hearing loss results from a functional deficiency of the POU3F4 protein [14] and various pathogenic hearing loss causing variants have been described in this gene, including intra-genic, partial, or complete deletions of the gene, and deletions, inversions, and duplications of the POU3F4 genomic region that do not include the POU3F4 coding sequence [15].