Novel missense mutations in PAX9 causing oligodontia

Area of Science:

• Genetics
• Developmental Biology
• Molecular Biology

Background:

• Oligodontia, a congenital condition characterized by the absence of six or more teeth, can be caused by genetic factors.
• The PAX9 gene plays a crucial role in tooth development.

Purpose of the Study:

• To identify the genetic cause of oligodontia in Chinese families.
• To elucidate the pathogenic mechanisms of identified PAX9 mutations.

Main Methods:

• DNA sequencing of MSX1 and PAX9 genes in affected families and controls.
• Site-directed mutagenesis to create mutated PAX9 vectors.
• Functional assays including immunofluorescence, electrophoretic mobility shift assay (EMSA), and luciferase reporter assays.

Main Results:

• Two novel missense mutations, Leu27Pro (L27P) and Ile29Thr (I29T), were identified in the paired domain of PAX9.
• Mutated PAX9 proteins retained nuclear localization but lost the ability to bind DNA and transactivate the BMP4 promoter.
• These findings suggest impaired transcriptional activity of the mutated PAX9 protein.

Conclusions:

• Novel mutations in the PAX9 gene are associated with oligodontia in Chinese families.
• The identified PAX9 mutations disrupt DNA binding and transcriptional activity, leading to tooth agenesis.