Number of amino acid (AA) changes of all human (n = 9340) and mouse (n = 6657) sequences is shown. A Total number of AA changes in the V regions of VH domain. B The number of AA changes observed in FR1, CDR1, FR2, CDR2, and FR3 of VH domain, with the mean ± SD. The p values were determined using ANOVA. All statistically significant differences are indicated. * = p < 0.05, ** = p < 0.01, *** = p < 0.001.