A Case of a Novel Noggin (NOG) Gene Mutation in Congenital Hearing Loss

Congenital stapedial fixation is a type of conductive hearing loss in which impairment of the sound-conduction mechanism is caused by congenital or acquired fixation of the stapes. It is genetically heterogeneous, but it has been recently reported to be also caused by mutations in the Noggin (NOG) gene. The authors have experienced a 6-year old boy with bilateral mixed hearing loss, who has a family history of hearing loss. No stapedial reflex was observed, and temporal bone CT showed no abnormality in the middle ear, as well as in the ossicles. Genetic study revealed novel NOG gene mutations, which have never been reported before as a relevant gene mutation for congenital hearing loss related with stapedial fixation. Under the possible diagnosis of congenital stapedial fixation with mixed hearing loss caused by NOG gene mutations, the patient has started to wear bilateral hearing aids and is being followed up for possible surgical therapy. Here, we report this case of congenital mixed hearing loss caused by novel NOG gene mutations with a review of the literatures.