Identification of a nonsense mutation in the PAX9 gene in molar oligodontia

Development of dentition is controlled by numerous genes, as has been shown by experimental animal studies and mutations that have been identified by genetic studies in man. Here we report a nonsense mutation in the PAX9 gene that is associated with molar tooth agenesis in a Finnish family. The A340 T transversion creates a stop codon at lysine 114, and truncates the coded PAX9 protein at the end of the DNA-binding paired-box. All the affected mem bers of the family were heterozygous for the mutation. The tooth agenesis p henotype involves all permanent second and third molars and most of the fir st molars and resembles the earlier reported phenotype that was also associ ated with a PAX9 mutation. The phenotype is presumably a consequence of hap loinsufficiency of PAX9. In another Finnish family with molar tooth agenesi s, we could not find similar sequence changes in PAX9.