A statistic useful for detecting deviations from the Hardy-Weinberg equilibrium in population genetics is discussed. Both exact and asymptotic distributions are given and a special case where there is misclassification is discussed. The distribution obtained also arises from a certain card matching problem.
"On a Matching Problem Arising in Genetics." Ann. Math. Statist. 20 (1) 91 - 94, March, 1949. https://doi.org/10.1214/aoms/1177730093