Amino acid insertions and deletions contribute to diversify the human Ig repertoire

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Abstract
Summary: The sequence analysis of Ig variable region genes transcribed within different B-cell subpopulations from human tonsil led us to identify a rare DNA sequence modification event consisting of Lip insertions and/or deletions (I/D). Although these events were previously reported, they had never been formally associated with the somatic hypermutation process. I/D events share with more convemtional somatic hypermutation events their localization within hypervariable regions and, most particularly, within DNA motifs known to be mutational hoc spots, Repetitive; DNA tracts or DNA elements capable of forming DNA loop intermediates seem to be the preferred substrate for I/D to occur. These characteristics suggest a model for somatic hypermutation reminiscent of the “polymerase slippage” model involved in replication and repair mutations in prokaryotes, yeast, and mammals.
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