Detection of clonal TCRG rearrangement by heteroduplex analysis of PCR products amplified with TCR Vγ- and Jγ-specific primers, as indicated and electrophoresed on polyacrylamide gels. Peer and peripheral-blood lymphocytes (PBL) represent clonal and polyclonal controls, respectively; MW indicates molecular weight markers. Four samples from M3v APL are demonstrated, 2 of which demonstrate clonal TCRG rearrangements (monoallelic in no. 12 and biallelic in no. 10). Clonal rearrangements are indicated by arrows. Higher molecular weight discrete bands for sample no. 10 correspond to clonal heteroduplexes.