Because of the variability, presumably due to the other genes in a dosage sensitive pathway, members of a family may be affected to different degrees. There is no evidence in the British studies that children are more severely affected than their parents, although jaw cysts and basal cell carcinomas may be detected earlier through surveillance and may give the impression that these features have occurred at an earlier age.

The skeletal signs are non-progressive and are not consistent between family members.

10% of adults with the syndrome develop neither jaw cysts nor basal cell carcinomas. It is unusual for new jaw cysts to appear from about the mid-thirties. A child where the diagnosis is made on histological examination of an isolated lesion will not necessarily develop a large number of basal cell carcinoma later.

The British studies gave a clinical impression that some families seem especially prone to develop BCCs - occurring at a younger age and in greater number - than other families, in which members develop relatively few BCCs, and perhaps much later in life.

The congenital malformations, however, generally do not follow a family-specific pattern: it's unusual for several family members to be severely affected.