Statistical distributions of oligonucleotide combinations: applications in human chromosomes 21 and 22

Statistical properties of distances between all quintuplets and hexaplets are calculated and long-range distributions are observed for certain quintuplets and hexaplets, common in human chromosomes 21 and 22. The oligonucleotides were ordered according to their power-law exponents and this ordering has separated quintuplets or hexaplets which contain consensus sequences of promoters from other random oligonucleotides. These results are in accordance with earlier observations and theoretical predictions and demonstrate a different aspect of long-range correlations in genomic sequences. Comparison of the statistical properties of quintuplets and hexaplets between the two chromosomes is undertaken and it is shown that statistics are universal in the two chromosomes.