Restriction map of the AML1 gene. Chromosomal orientation from telomere to centromere is as indicated. Exons 1, 2, and 3 are shown as solid boxes (▪). The location of the breakpoints in different patients is indicated by a bracket. Restriction enzyme sites are C, ClaI; M, MluI ; N,NotI; and S, SalI. The two overlapping P1 artificial chromosome clones containing either AML1 exon 1 or exon 2 and 3 are depicted below the AML1 restriction map.