Percent homology to germ line for commonly used AL
IgVL genes. The percent homology (%) is a reflection of the frequency with which individual nucleotides in an Ig gene have been mutated from germ line. Percents were determined for individual AL Ig VL genes correctly sequenced with L-CL primers. Aggregate results are depicted by germ line subgroup; medians and ranges for specific subgroups are shown on the chart and P values of Mann-Whitney comparisons in the table. The 6a genes are the most homologous to germ line and the 3r genes the least. The difference between 6a versus 2a2 or 3r Vλ genes achieves statistical significance. Because the 6a donor is not a common contributor to the normal expressed repertoire, the difference in homology with genes of other Vλ subgroups may reflect a normal process that distinguishes infrequently used germ line genes but may also reflect the propensity of 6a clones to produce amyloid due to germ line-encoded features. It may also reflect a difference in the origins of AL clones. For example, one might in theory see such a contrast if 6a clones were derived from de novo postgerminal center B cells, whereas clones of other Vλdonors were derived from memory B cells subject to additional circuits through the germinal center.
