Understanding the molecular pathogenesis of SOX9 Y440X campomelic dysplasia

Human SOX9 mutations cause the skeletal malformation syndrome campomelic dysplasia (CD). Complete inactivation of the Sox9 gene in mice results in failure of cartilage formation. Studies in zebrafish and Xenopus suggest that Sox9 may be crucial for specification of the otic placode. In mice, loss of Sox9 results in failure of otic placode invagination. Heterozygous mutations in human SOX9 result in conductive and sensorineural deafness in some CD patients, implying a later morphogenetic role but phenotypic details are limited. Sox9-/- null mice die before morphogenesis of the inner ear is complete, precluding investigation of the role of Sox9 later in ear develop...postprin