Based on the neighboring dual nucleotides, we introduce a novel 2D graphical representation of DNA sequences. We associate each sequence with mutation properties of neighboring bases by giving a 2D graphical representation, and thus obtain a seven-component vector relative to seven different classifications of mutations. The introduced vector is applied to characterize and compare the coding sequences of the first exon of beta-globin gene of 11 different species. (C) 2007 Elsevier B.V. All rights reserved.