DNA sequences at the breakpoints in FL4104 and FL5117.

In each case, (A) FL4101 and (B) FL5117, 3 breakpoints were present: the 5′-BCL2/JH junction, the 3′-BCL2/DH junction, and the deletion breakpoint joining the BCL2 5′- and 3′-flanking regions. The breakpoints are aligned with the germline sequences of JH, DH, 5′-BCL2, and 3′-BCL2. Germline sequences are from the following GenBank accession numbers: DH, X97051; 5′-BCL2, X51898; and 3′-BCL2,AF204739. JH sequences are from GenBank, accession number J00256 and from V BASE36; N-nucleotides are underlined and in italics. Natural and cryptic RSS heptamers and nonamers are boxed. All sequences were obtained from 2 sequence reactions in different orientations. (C) An alignment of the cryptic RSS elements in FL4104 and FL5117 with the consensus IGH RSS. In both cases, the sequence of the cryptic RSS in the JH4 5′-BCL2 fusion product has a few mismatches with the published germline sequence. Possibly these mismatches represent somatic mutations acquired after the translocation. Therefore, the germline sequence has been aligned with the consensus RSS.