GPRASP2 and Atresia of the external auditory canal: Among these causative mutant genes for syndromic hearing loss (SHL), GPRASP2 (DFNX7, OMIM:300969) was shown to be associated with X-linked external auditory canal atresia-dilated internal auditory canal-facial dysmorphism syndrome, while COL4A5 (OMIM:301050) was implicated in Alport syndrome (OMIM: 301050) and TIMM8A (OMIM:300356) in deafness-dystonia-optic neuropathy syndrome (Mohr–Tranebjærg syndrome OMIM: 304700).