  Pyrosequencing is emerging as one of the important next-generation sequencing
technologies. We derive the statistical distributions of this technique in
terms of nucleotide probabilities of the target sequences. We give exact
distributions both for fixed number of flow cycles and for fixed sequence
length. Explicit formulas are derived for the mean and variance of these
distributions. In both cases, the distributions can be approximated accurately
by normal distributions with the same mean and variance. The statistical
distributions will be useful for instrument and software development for
pyrosequencing platforms.
