1. ¹Institute of Dentistry, University of Helsinki, Finland
2. ²Department of Oral and Maxillofacial Diseases, Helsinki University Central Hospital, Finland
3. ³Institute of Biotechnology, University of Helsinki, Finland

Correspondence: Dr L Lammi, Institute of Dentistry, c407b, Biomedicum Helsinki, PO Box 63, University of Helsinki, FIN 00014, Finland. Tel: +358 505 434 650; Fax: +358 9 191 25371; E-mail: laura.lammi@helsinki.fi

Received 11 March 2003; Revised 30 May 2003; Accepted 5 May 2003.

Abstract

Mutations in PAX9 have been described for families in which inherited oligodontia characteristically involves permanent molars. Our study analysed one large family with dominantly inherited oligodontia clinically and genetically. In addition to permanent molars, some teeth were congenitally missing in the premolar, canine, and incisor regions. Measurements of tooth size revealed the reduced size of the proband's and his father's deciduous and permanent teeth. This phenotype is distinct from oligodontia phenotypes associated with mutations in PAX9. Sequencing of the PAX9 gene revealed a missense mutation in the beginning of the paired domain of the molecule, an arginine-to-tryptophan amino-acid change occurring in a position absolutely conserved in all sequenced paired box genes. A mutation of the homologous arginine of PAX6 has been shown to affect the target DNA specificity of PAX6. We suggest that a similar mechanism explains these distinct oligodontia phenotypes.