Wiedemann-Beckwith syndrome: autosomal-dominant inheritance in a family.

We report four additional cases of Wiedemann-Beckwith syndrome (WBS): A mother, her brother, and two of her children (half-sibs). Theories of the genetic transmission of the WBS are reviewed. The trait in this family appears to be an autosomal-dominant with variable expressivity. A theory of delayed mutation of an unstable premutated gene is discussed and an interpretation and observations are offered which could alter slightly the expected pattern of inheritance. Eighty-eight other family members were screened for evidence of WBS and noteworthy findings are presented.