(A) Analysis of bcr-abl rearrangement from dried blood specimen in patients with CML. Lanes 1 and 2, patient no. 1 post-BMT (d +28 and d +49, respectively). Note that a faint bcr-abl signal is visible in lane 1 but not in lane 2. Lane 3, patient no. 2 under treatment with interferon-α2; sample was processed after 7 months of storage. Lane 4, patient no. 3 at the time of diagnosis exhibiting a b3a2 rearrangement. Lane 5, patient no. 4 without amplificable bcr-abl rearrangement on the time of diagnosis; note, however, that the abl-specific mRNA was amplified (see [B]). Lane 6, negative control (water). Lane 7, positive control (cell line K562). Lane 8, 100-nt length marker. (B) Seminested RT-PCR amplification using primers for abl exon 1a, exon 1b, and exon 2, showing that intact abl-gene mRNA is present in all extracted specimen, including those cases (patients no. 1 and 4; compare with lane 2 and lane 5 in [A]) in which no bcr-abl rearrangement could be detected. Lanes 6 through 8 are the same as in (A).