Holt-Oram syndrome in four half-siblings with unaffected parents: brief clinical report.

The Holt-Oram syndrome was diagnosed in four offspring of three mothers and the same unaffected father. One additional child lacked the characteristic clinical features of the Holt-Oram syndrome. In contrast to the general autosomal dominant inheritance with complete penetrance, our observation suggests a paternal mutation, resulting in mosaicism, probably restricted to the germline.