Osteogenesis imperfecta: the audiologic phenotype lacks correlation with the genotype

Objectives : Osteogenesis imperfecta (OI) is commonly associated with hearing loss. To unravel the characteristics of the hearing loss and their interindividual variability, hearing was thorougly investigated in a large number of patients. Additionally, the associations between the occurrence and characteristics of the hearing loss and the underlying mutations were studied. Methods : After identification of the COL1A1 and COL1A2 mutations, a total number of 184 OI patients aged 3-89 years and originating from 89 different families were evaluated audiometrically. A sample of 114 patients was involved in an audiological phenotype – genotype correlation study. Results : Hearing loss was diagnosed in 48.4% of ears with increasing prevalence toward older age groups. The predominant type was a mixed hearing loss (27.5%). A minority of ears presented a conductive (8.4%) or pure sensorineural (12.5%) loss. No association was found between the COL1A1 or COL1A2 mutations and the occurrence, type or severity of hearing loss. Despite an identical mutation, even relatives originating from the same family differed considerably in audiological features. Conclusions : Hearing loss in OI is associated with a strong inter- and intrafamilial variability and appears to develop independently of the underlying OI genotype. Additional modifications in other genes are assumed to be responsible for the expression of hearing loss in OI