A comment on sorting by translocations

Genome rearrangement is an important research area that studies the ordering of genes in the evolution of gene families. With the advent of large-scale DNA computing genome rearrangements are becoming increasingly important day by day in evolutionary molecular biology. Translocation is one of the important rearrangement event in the evolution of mammalian species as multi chromosomal genome frequently evolves by rearrangement events called translocation. Translocation exchanges genetic material between different chromosomes. Given two multichromosomal genomes A and B, the problem of sorting by translocation is to find a shortest sequence of translocations to transform A into B. It is observed that the distance formula (minimum number of translocations to be used) between genome A and B given by Anne Bergeron et al. fails in some cases. In this paper, we present some of such cases and also provide a modified distance formula.