Molecular analysis of patients with Wiedemann-Beckwith syndrome. II. Paternally derived disomies of chromosome 11.

In Wiedemann-Beckwith syndrome (WBS) a putative disease gene resides at the tip of the short arm of chromosome 11 in the region of the insulin growth like factor II (IGF-II) gene. Whilst changes in gene dosage in this area do not appear to be common in the syndrome, in familial cases the lesion appears to be dominant only when inherited through the female line. We undertook to examine the parental origin of the copies of chromosome 11 in a large group of WBS patients using a series of restriction fragment length polymorphisms (RFLPs) on 11p, and report here that in one sporadic case of WBS out of 14 both copies of chromosome 11 are derived from the father and are present in a normal dosage. This suggests that at least one mode of expression of the lesion is modified by genomic imprinting.