We present in this paper a theoretical analysis that relates an irregularity measure of a fitness function to the so-called GA-deception. This approach is a con­ti­nua­tion of a work that has presented a deception a­na­ly­sis of Hölder functions. The analysis developed here is a generalization of this work in two ways¸: we first use a «bitwise regularity» instead of a Hölder exponent as a basis for our deception analysis, second, we perform a similar deception analysis of a GA with uniform crossover. We finally propose to use the bitwise regularity coefficients in order to analyze the influence of a chromosome encoding on the GA efficiency, and present experiments with bits permutations and Gray encoding.