  Periodic patterns play the important regulatory and structural roles in
genomic DNA sequences. Commonly, the underlying periodicities should be
understood in a broad statistical sense, since the corresponding periodic
patterns have been strongly distorted by the random point mutations and
insertions/deletions during molecular evolution. The latent periodicities in
DNA sequences can be efficiently displayed by Fourier transform. The criteria
of significance for observed periodicities are obtained via the comparison
versus the counterpart characteristics of the reference random sequences. We
show that the restrictions imposed on the significance criteria by the rigorous
spectral sum rules can be rationally described with De Finetti distribution.
This distribution provides the convenient intermediate asymptotic form between
Rayleigh distribution and exact combinatoric theory.
