Individual Hardy-Weinberg Proportion Testing  

                        John J. Chen  

                   Division of Biostatistics 
                 University of California at Berkeley 
                      Berkeley, CA 94720-3140 

It is often of interest to detect the deviation from Hardy-Weinberg 
Proportion (HWP) for a particular heterozygote. 
Hernandez and Weir (1989) suggested a disequilibrium coefficient 
approach and proposed a one degree of freedom chi-square test. We derive 
the appropriate variance for performing this individual HWP test.
In practice, however, the number of genotypes in a sample 
can be quite large relative to the sample size. Therefore, the validation 
of this asymptotic test is in doubt. We have proposed a Monte Carlo
method for  performing such tests. Powers of the individual tests are
compared for the large-sample approach and the Monte Carlo approach,
and for different test statistics.  Results of applying the individual
test to several human genetic data are also presented.