highly significantP < 10 −5
However, supporting a direct, specific role for Fanca during SHM, we observed that the frequency of mutations at A/T residues was significantly reduced in Fanca −/− mice (P = 10 −4 ; Table 1 ), and this reduction was associated with a highly significant (P < 10 −5 ) decrease in the frequency of transitions at these sites ( Table 1 ).