Immunogenetics of response to a purified antigen from group A streptococci. II. Linkage of response to HLA.

Employing an in vitro blastogenesis model, evidence has been set forth for a major gene locus which controls response to a purified, extracellular antigen from group A streptococci. Response to this antigen is inherited in an autosomal dominant manner. Analysis of the data for linkage to HLA was done with the computer program LINKAS which can resolve pleiotropy from linkage and can detect and estimate recombination in the presence of etiological heterogeneity. Maximum likelihood estimation and likelihood ratio tests were used to assess the relative support for competing hypotheses. The results of this analysis indicate that at least two loci are involved in one of two ways: one locus that is closely linked to HLA and one locus that is unlinked; or a two-locus system of complementary alleles which are both tightly linked to HLA.