Characteristics of incisor-premolar hypodontia in families

Nonsyndromic tooth agenesis is a genetically and phenotypically heterogenou s condition. It is generally assumed that different phenotypic forms are ca used by different mutated genes. We analyzed inheritance and phenotype of h ypodontia and dental anomalies in 214 family members in three generations o f 11 probands collected for genetic linkage study on incisor-premolar hypod ontia (IPH), Our analysis confirms the autosomal-dominant transmission with reduced penetrance of IPH. The prevalence of hypodontia and/or peg-shaped teeth was over 40% in first and second-degree relatives and 18% in first co usins of the probands. Four of nine noted obligate carriers of hypodontia g ene had dental anomalies, including small upper lateral incisors, ectopic c anines, taurodontism, and rotated premolars. These anomalies were also obse rved at higher than normal frequency in relatives affected with hypodontia. We conclude that incisor premolar hypodontia is a genetic condition with a utosomal-dominant transmission and that it is associated with several other dental abnormalities.