Explain linkage disequilibrium and how it relates to predicting the frequency of particular HLA ...

Example: An organ transplant candidate inherited MHC gene set A from his mother and MHC gene set B from his
father. An organ must be found that has both A and B MHC genes. If the frequency of A in the general population
is 1 and the frequency of B is 1 than the predicted probability of finding the two together is
frequency of A x frequency of B = 0.01 x 0.01 = 0.0001 or 1 in 10,000
In many cases, the prediction illustrated above is wrong, and in certain populations the incidence of particular gene
combinations is higher than predicted. This is called linkage disequilibrium. Since many examples of linkage
disequilibrium seem to be related to ethnicity and/or nationality, knowledge of the gene pool in various ethnic
populations can be useful to more easily identify compatible donors.