RESUMEN
Otosclerosis, the single most common cause of hearing impairment in white adults, is characterised by bone dystrophy localized to the otic capsule and isolated endochondral bone sclerosis with alternating phases of bone resorption and formation. Conductive hearing loss develops when otosclerotic foci invade the stapedio-vestibular joint (oval window) and interfere with free motion of the stapes, but affected subjects frequently develop profound sensorineural hearing loss. The aetiology of otosclerosis is unknown. In the last years, several association studies have been performed and have suggested that single nucleotide polymorphisms in some genes may be implicated in development of otosclerosis. The strongest association has been demonstrated for the reelin gene, located on chromosome 7q22.1, which encodes an extracellular matrix protein. The involvement of reelin in the pathogenesis of otosclerosis is controversial; it was identified in European and North African populations, but was excluded in an Indian population. To analyze the role of reelin in otosclerosis, it has been studied in a case-control analysis for the polymorphism rs39335 in a southern Italy population. In this population, the pathogenic link between the rs39335 variant and otosclerosis was excluded.