Evidence of intraclonal heterogeneity in IgV_H genes of monoclonal B-cell PTLDs. Sequence alignments of the IgV_H clones derived from PTLD cases 3459, 3518, 3528, 3522, and 2890. The sequences of clones were aligned and compared with the most homologous germ-line IgV_H, D, and J_H sequences. Identity with the most homologous germ-line sequence is indicated by dashes. Each mutation is indicated by the appropriate nucleotide: replacements mutations by uppercase letters and silent mutations by lowercase letters; Δ symbol indicates nucleotide deletion. N-additions between IgV_H and D, as well as between D and J_H segments, are shown for each sequence. CDR indicates complementarity determining region; FR, framework region.