The Wiedemann-Beckwith syndrome: pedigree studies on five families with evidence for autosomal dominant inheritance with variable expressivity.

We describe 18 individuals from five unrelated families with various manifestations of the Wiedemann-Beckwith syndrome. Pedigree analysis was performed on the 5 families and on another 19 families in the literature, each of which included more than one affected person. The following findings were obtained: 1) the clinical manifestations among the affected individuals were highly variable--those obvious in infancy tended to become less distinct with increasing age; 2) the syndrome was transmitted directly and vertically through three generations in four families, and through two generations in seven families; 3) male-to-male transmission was noted once; 4) the sex ratio in the affected individuals was not significantly different from 1; 5) the segregation ratio of the trait among the sibs of the probands was 0.571 +/- 0.066; 6) the affected + carrier/normal ratio was one among the offspring of the affected individuals and obligate carriers; 7) phenotrance (the expected presence of the trait in a generation) of the syndrome in the sibship of probands was complete, whereas that in earlier generations appeared low. The discrepancy is attributable to the lessening of the clinical features with increasing age as well as to a possibly less aggressive search for abnormalities in older generations. These findings indicate that the syndrome is an autosomal dominant trait with variable expressivity. High-resolution chromosome banding analysis in seven affected individuals and their respective parents showed no abnormalities.