Size and frequency of the DNA fragments in the rearranged immunoglobulin heavy chain joining regions in the lymphocytic leukemias.

Four distinct groups of DNA fragments produced by the rearrangement of the joining regions of the immunoglobulin heavy chain gene were found after hydrolysis of the leukemic DNA with the EcoR I restriction enzyme. Three fragments were smaller than the genomic fragment (16 kb) and their average sizes were 9.6, 11.2, and 13.7 kb. The largest fragment was 18.7 kb. The fragment groups 2 and 3 (11.2 and 13.7 kb) were found in 65 per cent of the cases. There was no correlation between the fragment groups and the acute or chronic lymphocytic leukemia or B-cell lymphoma.