A novel POU domain class 3 transcription factor 4 mutation causes X-linked non-syndromic hearing loss in a Chinese family

To the Editor: POU domain class 3 transcription factor 4 or BRN-4 (POU3F4) is a causative gene of non-syndromic X-linked hearing loss (HL), which is characterized by inner ear anomalies. To date, six X-linked non-syndromic HL loci (DFNX1-6) have been mapped to chromosome X and five of these genes have been identified: phosphoribosyl pyrophosphate synthetase 1 (PRPS1)(DFNX1, OMIM: 304500), POU3F4 (DFNX2, OMIM: 304400),[1] small muscle protein, X-linked (SMPX)(DFNX4, OMIM: 300066), apoptosis-inducing factor, mitochondria-associated, 1 (AIFM1)(DFNX5, OMIM: 300614), and collagen, type IV alpha-6 (COL4A6)(DFNX6, OMIM;300914). POU3F4 mutation accounts for nearly 50% of all cases of DFNX.