Method: We investigated whole genome amplified DNA samples from 90 individuals participating in our tooth agenesis study. Intron based primers were designed to PCR-amplify the coding exons of PITX2-001. PCR products were purified and sent to GenScript for DNA sequencing. DNA sequences were scanned visually for mutations, and compared to the (NCBI) reference genome by BLAST.
Result: One new missense mutation was found in the coding region of exon 5. This transversion from C to A at c.723 (PITX2-001) results in a serine to arginine change of amino acid 241. The mutation was not found in Ensembl databases (ESP and 1000Genomes). Two synonymous mutations in exon 5 and several variants within the non-coding region of exon 2 were also found, but with the same frequency as reported for control populations in Ensembl. No mutations were found in exons 3 or 4.
Conclusion: It is not yet clear whether the Ser241Arg mutation in Pitx2 is responsible for the tooth agenesis in our patient. The mutation is located in a highly conserved region, providing motive for further research. Genetic testing of the patient’s relatives will be necessary to document whether the mutation segregates with tooth agenesis in the family. Axenfeld-Rieger syndrome is typically caused by mutations within the homeodomain of PITX2 (exon 4); it is conceivable that a milder phenotype like tooth agenesis could be due to variants in other domains of the protein.