Table III.

Target nucleotide mutation frequency (%) in hypermutable motifs in nonproductive VH rearrangements

Mutated Base	Motif	AICDA−/−	Normal Donor
G	inside RGYW	2/2374†	94/937*
		0.08%	10.0%
	all other G	18/13016†	99/6093
		0.14%	1.6%
C	inside WRCY	0/2140†	62/832*
		0%	7.5%
	all other C	7/13596†	75/5685
		0.05%	1.3%
A	inside WA	4.5/8273†	115.9/2473*
		0.05%	4.7%
	all other A	6.5/8564†	79.1/3615
		0.08%	2.2%
T	inside TW	1.5/5180†	56.5/1550*
		0.03%	3.6%
	all other T	3.5/8288†	45.5/3714
		0.04%	1.2%

The targeted nucleotide refers to the base in the underlined position (or two positions in WA where W=A or T). The mutation frequency of the targeted nucleotide inside a motif was calculated from the number of target nucleotide mutations divided by the total number of the motif (or total number of A in WA motifs). To calculate the mutation frequency outside the motif, the total number of base mutations in the sequence minus the number of targeted nucleotide mutations was divided by the total number of the base in the sequence minus the number of target nucleotides inside the motif. The extent of targeting was determined by calculating the fold difference between the mutation frequency inside a motif vs all other positions.

^*Significant (p<0.01) difference between the nucleotide mutation frequency inside a motif vs all other positions

^†significant (p<.0001) difference between AICDA^−/− and normals.