Amelogenesis imperfecta--clinical manifestations in 51 families in a northern Swedish county.

The clinical manifestations of amelogenesis imperfecta (AI) were described in 165 individuals from 51 families. The inheritance pattern for AI in these families had previously been investigated, and it was hypothesized that AI probably is solely an autosomal dominant (AD) or X-linked trait. To test this hypothesis the connection between clinical manifestation and inheritance pattern was studied. Eight different variants of AI were seen. In 33/51 families all affected individuals could be assigned to the same clinical variant. In 8/51 families those affected were assigned to different clinical variants. In the two families where an X-linked recessive (XR) inheritance pattern was found probable, the clinical manifestation differed between women and men. Except for one variant only seen as an AD trait, and the manifestation in women in families with an X-linked recessive inheritance pattern, no connection was found between a specific inheritance pattern and a specific clinical manifestation. Accordingly it seems likely that AI is solely an AD or X-linked trait. The different clinical variants observed should be regarded as a varying expressivity of the gene and in the families with X-linked inheritance probably due to lyonization. In the remaining families the modifying mechanisms are not known.