Figure 4. .

Analysis of the DIP2B CGG repeat in controls (“C”) and individuals expressing the FRA12A fragile site (in family B, subjects I.2 and II.2; in family A, subjects I.2, II.2, and III.1). In addition to a normal allele (“N”; 250 bp), individuals who cytogenetically express the FRA12A site show additional PCR fragments of larger size (“F”), indicating repeat expansion. The length of the expanded allele in the unaffected FRA12A carriers (subjects I.2 and II.2 of family A and subject I.2 of family B) is 650–850 bp. In the two patients with FRA12A (subject III.1 of family A and subject II.2 of family B), the length of the expanded allele is >1,050–1,150 bp.