IC1 structure in the three-generation BWS family with WT. (A) Pedigree of a large three-generation family with three children affected by BWS and WT. *, Those individuals who inherited the same 11p15 maternal haplotype, along with the IC1 deletion described in this report. The proband (III.1) is indicated by an arrow. (B) Organization of the paternal and maternal IC1 region in members of the BWS/WT pedigree. The integral DMR status on the paternal haplotype of individuals III.1, III.2, III.3, III.4, and III.5 is shown, with B repeats represented by yellow boxes and A repeats denoted by gray boxes. The locations of the CTCF-binding sites are denoted by small orange hatches. The core CTS sequence is shown, with the blackened C or green T, denoting a paternal or maternal single-nucleotide polymorphism (SNP), respectively. Nucleotides specific for the B1 and B5 sequences are marked in red and blue, respectively. The microdeletion generates a chimeric CTS sequence derived from B1 and B5 repeats in the maternal haplotypes of III.1, III.2, III.4, and III.5. The heterozygous nature of the deletion in III.1 was verified by Southern blot analysis (Left).