  We present an exact, closed expression for the expected neutral Site
Frequency Spectrum for two neutral sites, 2-SFS, without recombination. This
spectrum is the immediate extension of the well known single site $\theta/f$
neutral SFS. Similar formulae are also provided for the case of the expected
SFS of sites that are linked to a focal neutral mutation of known frequency.
Formulae for finite samples are obtained by coalescent methods and remarkably
simple expressions are derived for the SFS of a large population, which are
also solutions of the multi-allelic Kolmogorov equations. Besides the general
interest of these new spectra, they relate to interesting biological cases such
as structural variants and introgressions. As an example, we present the
expected neutral frequency spectrum of regions with a chromosomal inversion.
