Table 2.

Mutation properties in the proximity of CSR junctions

	GC bias		Transition bias		RGYW/ WRCY bias
	A/T	G/C	Transversion	Transition	Motif	Nonmotif
Observed	7	35	14	28	32	10
Expected	17	25	28	14	24	18
Significance	P = 0.030		P = 0.0023		P = 0.055

Forty-two mutations are classified according to their targeted nucleotide (A/T or G/C), pattern (transversion or transition), and surrounding nucleotides (RGYW/WRCY hot spot motif or not). Expected values were calculated according to average frequency of G/C (60.5%), the hot spot motifs (56.5%) in Sμ and Sα regions. When mutations occur randomly, transversion occurs twice more frequently than transition. Statistical analysis was done by Fisher's exact probability test or χ² test.