Novel missense mutation in PAX9 gene associated with familial tooth agenesis.

[oligodontia]

PAX 9 is a transcription factor deeply involved in the gene networks that regulate odontogenesis . To date , only a restricted number of mutations in this gene have been associated with non-syndromic tooth agenesis . Six families segregating non-syndromic oligodontia /hypodontia were screened for mutations in PAX 9 gene . A novel missense mutation lying in the exon 2 close to the end of the paired domain in three families was identified . Heterozygous mutation C 5 03 G is expected to result in an alanine-to -glycine amino acid change in residue 168 (Ala 168 G ly ), which is invariably conserved among several species . The alanine-glycine change might lead to protein structural alteration because of the unique flexibility properties of glycine . Three mutations in intron 2 were also detected . Variations IVS 2 -109 G >C , IVS 2 -54 A >G , and IVS 2 -41 A >G were identified in both affected and unaffected members of the sample ; however , these polymorphic variants may be involved in the phenotype as one proband showing all three intronic mutations in homozygosis was affected with the most severe oligodontia within the sample .