Intron-exon patterns as a potential tool in studying gene evolution

The majority of introns are ancient elements and their phases and positions in genes were preserved for a long time. A string of intron phases represents a structure which carries essential information about organization and evolution of genes, which is usually ignored. Numerous observed strings have non-random intron phase patterns caused by intragenic repeats. Correlation between the lengths of CDS and the number of introns per human gene is high. Lengths of exons often remain constant in homologous and even paralogous genes belonging to distant species. Alignment of exon-intron strings provides useful visualization and generates new knowledge about evolution of gene families. It unravels intragenic duplications, intron gains and losses as well as extensions and contractions of exons. This additional information seems to be useful for studying gene evolution.