A location score comes from calculating probabilities of data under an
hypothesis 
specifying a disease susceptibility (DS) locus linked
to the markers at a specified location x compared with 
that all
DS locus are unlinked to the markers. By convention, the location
score is the base 10 log of the likelihood ratio. It is often referred
to as LOD score that stands for Logarithm of ODds.
Data include multilocus marker genotypes m and affectedness
status of the individuals in the pedigree 
.
This statistic is natural for Bayesians. We start with a prior
probability 
that a DS locus is exactly at x. Then we collect
data and compute a posterior probability.
A LOD score is equivalent to a normalized posterior distribution
assuming a uniform prior for the hypothesis 
.