Figure 1. Oral photographs of the unaffected mother (II-2) and the proband (III-1; age 11) show that the MSX1 mutation (g.62dupG) has no apparent effect on tooth size (top). Panorex radiographs demonstrate that the unaffected mother (II-2) has all of her permanent teeth except the third molars, while the proband (III-1) is missing 6 teeth, and his affected sister (III-2; age 9) is missing 12 teeth, not counting the third molars. A white dot indicates the expected location of a congenitally absent tooth. The pedigree indicates that the oligodontia trait in this family was transmitted from the father to the offspring in an autosomal-dominant pattern of inheritance. DNA sequencing chromatograms (bottom) identified the specific MSX1 frameshift mutation (arrows) in both the forward and reverse directions. This mutation was not observed in the wild-type (Wt) MSX1 gene in the unaffected members of the kindred.