Assignment of the canine cadherin related 23 gene (CDH23) to chromosome 4q12-->q13 by fluorescence in situ hybridization and radiation hybrid mapping.

Cadherin related gene (CDH23), which encodes otocadherin is a novel member of the cadherin gene superfamily. CDH23 mutations were found in families with nonsyndromic autosomal recessive deafness (DFNB12), and in families with deafness associated with vestibular dysfunction and retinitis pigmentosa (USH1D), respectively (Bolz et al., 2001; Bork et al., 2001; Petit, 2001). DFNB12 has been located on HSA10q21→ q22 by linkage mapping (Chaib et al., 1996). In the waltzer mouse it was shown that mutations in the orthologous Cdh23 gene cause disorganization of inner ear stereocilia leading to deafness (Di Palma et al., 2001). Cdh23 expression was detected in the murine neurosensory epithelium. Otocadherin is a critical component of hair bundle formation and in Cdh23 deficient mice the stereocilia organization was disrupted during early hair cell differentiation (Di Palma et al., 2001). Congenital sensorineural deafness in dogs may result from degeneration of the hair cells of the organ of Corti (Strain, 1996; Coppens et al., 2000; Poncelet et al., 2000). Therefore, CDH23 might be a suitable candidate gene for congenital nonsyndromic hearing loss in dogs. To facilitate future linkage studies we report here the assignment of the canine CDH23 gene to CFA4q12→q13 by FISH and RH mapping. Materials and methods