This article is aimed at defining guidelines for dental surgeons to manage patients with warning signs of rare genetic diseases. Anomalies of tooth development may occur as an isolated condition or in association with other symptoms in syndromes. In many cases, dental anomalies may be the first manifestations of a genetic disease. The dentist can contribute to the diagnosis, and hence to an early treatment of this syndrome. When one or more dental anomalies are found, practitioners should refer patients to a genetic clinic or a specialized reference center to diagnose genetic diseases. Therefore, we provide, for the first time, a table of extra-oral signs that dental surgeons can look for in patients exhibiting heritable dental developmental anomalies.