Novel missense mutations in PAX9 causing oligodontia.

[oligodontia]

We investigated the disease-causing gene of oligodontia in Chinese families and analysed the pathogenesis of mutations of this gene that results in oligodontia .Two families with oligodontia , but of different descent and 100 unrelated healthy controls were enrolled in our study . Genomic DNA was isolated from blood samples . Mutation analysis was performed by amplifying MSX 1 and PAX 9 exons and sequencing the products . After identifying the mutations , we performed site-directed mutagenesis to generate mutated vectors . The wild-type and mutated PAX 9 vectors were then transfected separately to NIH 3 T 3 cells . Immunolocalization , electrophoretic mobility shift assay (EMSA ) and luciferase reporter assay were performed to analyse the effects of mutations on protein function .We identified two novel missense mutations , Leu 27 P ro (L 27 P ) and Ile 29 Thr (I 29 T ) in the paired-domain of PAX 9 . Analysis of homologous PAX proteins indicated that these two substitutions may affect the function of the PAX 9 protein . Results of immunofluorescence and western blot showed that the mutations did not alter the nuclear localization of PAX 9 . EMSA and luciferase reporter assays indicated that both the mutated proteins could not bind DNA or transactivate the BMP 4 promoter .Two novel missense mutations in PAX 9 have been indentified in Chinese families causing oligodontia .