SOX10 mutations mimic isolated hearing loss.

[kallmann syndrome]

Ninety genes have been identified to date that are involved in non-syndromic hearing loss , and more than 300 different forms of syndromic hearing impairment have been described . Mutations in SOX 10 , one of the genes contributing to syndromic hearing loss , induce a large range of phenotypes , including several subtypes of Waardenburg syndrome and Kallmann syndrome with deafness . In addition , rare mutations have been identified in patients with isolated signs of these diseases . We used the recent characterization of temporal bone imaging aspects in patients with SOX 10 mutations to identify possible patients with isolated hearing loss due to SOX 10 mutation . We selected 21 patients with isolated deafness and temporal bone morphological defects for mutational screening . We identified two SOX 10 mutations and found that both resulted in a non-functional protein in vitro . Re-evaluation of the two affected patients showed that both had previously undiagnosed olfactory defects . Diagnosis of anosmia or hyposmia in young children is challenging , and particularly in the absence of magnetic resonance imaging (MRI ), SOX 10 mutations can mimic non-syndromic hearing impairment . MRI should complete temporal bones computed tomographic scan in the management of congenital deafness as it can detect brain anomalies , cochlear nerve defects , and olfactory bulb malformation in addition to inner ear malformations .