VDJ recombination events in patients with in vivo hydroxyurea exposure.

A 2-step nested PCR protocol amplifies rare recombination events between TCRγ variable and TCRβ junctional genes on chromosome 7. Dilutions of PBMC DNA ranging from 2.0 to 0.3 μg are listed for each sample. (A) Results for 2 patients with MPD and 2 normal controls. There are positive bands at 2.0 μg DNA for all 4 samples and at 1.0 μg DNA for 1 control. (B) Results for 4 patients with SCD, including 2 adults and serial samples from a child. The gel shows bands at 2.0 and 1.0 μg DNA for both adult patients. The child had a positive signal at 2.0 μg DNA after short-term HU therapy (7 months), but 2 years later had bands at 2.0 and 1.0 μg DNA. (−) is a negative control and (+) is a positive control.