Autoradiographs of leukemic DNA samples from patients P15, P4, P7, and P13 and control (C) and leukemic (L) samples were digested with the restriction enzyme EcoRI, size fractionated through 1% agarose gel, and hybridized with the following probes: (A) control probe renin; (B) p9E4.3, with densitometry results compared with the control signals of 0.05, 0.04, 0.40, and 0.53, showing homozygous loss for P15 and P4 and hemizygous loss for samples P7 and P13, respectively; and (C) showing the same samples hybridized with the probes (I, upper band) p6E3.2, a 800-bp EcoRI MluI probe isolated from the same genomic 3-kb EcoRI fragment as the polymorphic 6E3.2 marker, with densitometry results compared with the control signals of 0.08, 0.46, 0.41, and 0.47, respectively, showing homozygous loss, hemizygous loss, hemizygous loss, and hemizygous loss, respectively and (II, lower band) p9a, a 2-kb EcoRI fragment isolated in the overlapping region between cosmids C9a and C29a, with densitometry results compared with the control signals of 0.03, 0.48, 0.42, and 0.49, respectively, showing homozygous loss, hemizygous loss, hemizygous loss, and hemizygous loss, respectively.