Congenital absence of permanent teeth in a six-generation Chinese kindred.

We report on rare, heritable, permanent tooth agenesis in a large Chinese kindred. The congenital absence of permanent teeth except the first and second accessory teeth was observed in 52 individuals through six successive generations in the kindred comprising 328 members. Clinical assessments were carried out, and inheritance mode and spousal influence of the anomaly on their offspring were analyzed. Consequently, the anomaly was transmitted in an autosomal dominant fashion with incomplete penetrance (P = 0.88), and no significant clinical manifestations other than the oligodontia were found. A geographical or environmental effect on the affected individuals was obviously eliminated, because any who are related to the kindred but live under the same conditions are fully healthy. The disorder we describe, therefore, differs from any previously reported oligodontia/anodontia syndromes. The oligodontia ranged from a few teeth to the whole set of teeth, and usually occurred at a period from age 7 or 8 years, the time when primary teeth are normally replaced by permanent teeth, to the forties. Roentgenography of the affected persons indicated that only the first and/or second accessory teeth with tooth buds developed as permanent teeth. In fact, the diphyodontic germination sometimes occurred in the oral cavity of the affected individuals.