Distribution of ABO Blood Groups on the Indian Subcontinent: A Cluster-Analytic Approach [and Comments and Reply]

Abstract

This paper attempts a comprehensive statistical analysis of the O-A-B-AB blood-group frequencies collected from the Indian subcontinent. The objective is to examine the variation in ABO gene frequencies among populations using statistical tests of homogeneity and single-linkage cluster analysis. In all, 899 sets of phenotype frequency data were examined. Of these, 405, each based on a sample of at least 100 individuals and in conformity with Hardy-Weinberg equilibrium expectations, were subjected to detailed analysis. When the populations were cross-classified in terms of geographical location and socioreligious considerations, only 13 of the 32 nonempty subsets were homogeneous with respect to gene frequencies. Single-linkage cluster analysis was applied to the 19 remaining subsets to split them into smaller homogeneous subsets. This yielded 106 clusters homogeneous not only with respect to gene frequencies, but also in terms of geographical location and socioreligious considerations. By a second application of the technique, these clusters were combined into 39 "superclusters," each homogeneous with respect to gene frequencies but not in terms of geographical or socioreligious considerations. A dendrogram showing the resemblances among these superclusters in presented. The composition of the clusters and superclusters is examined in the light of ethnological evidence.