[A solitary central maxillary incisor and holoprosencephaly in siblings]

In families in which holoprosencephaly seems to be inherited by a rare dominant autosomal mutation, some individuals exhibit a single central maxillary incisor (SCMI). This anomaly was considered a minimal manifestation of the gene for holoprosencephaly. We report on a family, in which one child suffered from median cleft lip and palate and alobar holoprosencephaly, whereas the other child only had a SCMI. In the father and his sister lateral upper incisors were absent. Therefore the question is raised as to whether this anomaly may be related to the same condition.